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ofshex dumpascii
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1ac0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
1ae0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
1b00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
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1fe0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
2000 61 64 00 00 03 00 00 00 33 01 00 00 00 10 00 00 45 00 00 00 00 00 00 00 e5 0f 00 00 96 0f 00 00 ad......3.......E...............
2020 48 0f 00 00 00 0f 00 00 b0 0e 00 00 65 0e 00 00 1d 0e 00 00 ce 0d 00 00 ac 0d 00 00 ab 0d 00 00 H...........e...................
2040 98 0d 00 00 50 0d 00 00 03 0d 00 00 da 0c 00 00 d9 0c 00 00 cc 0c 00 00 7f 0c 00 00 41 0c 00 00 ....P.......................A...
2060 40 0c 00 00 13 0c 00 00 12 0c 00 00 fe 0b 00 00 b2 0b 00 00 86 0b 00 00 56 0b 00 00 21 0b 00 00 @.......................V...!...
2080 c9 0a 00 00 90 0a 00 00 25 0a 00 00 24 0a 00 00 d4 09 00 00 94 09 00 00 6c 09 00 00 38 09 00 00 ........%...$...........l...8...
20a0 37 09 00 00 ea 08 00 00 9d 08 00 00 60 08 00 00 19 08 00 00 ce 07 00 00 cd 07 00 00 80 07 00 00 7...........`...................
20c0 2f 07 00 00 e6 06 00 00 e5 06 00 00 d3 06 00 00 a6 06 00 00 65 06 00 00 36 06 00 00 de 05 00 00 /...................e...6.......
20e0 ac 05 00 00 de 04 00 00 dd 04 00 00 8d 04 00 00 56 04 00 00 06 04 00 00 fc 03 00 00 92 03 00 00 ................V...............
2100 6b 03 00 00 6a 03 00 00 4c 03 00 00 02 03 00 00 b7 02 00 00 6b 02 00 00 6a 02 00 00 1c 02 00 00 k...j...L...........k...j.......
2120 d1 01 00 00 81 01 00 00 33 01 00 00 00 00 00 00 00 00 00 70 6f 69 73 6f 6e 69 6e 67 2c 20 61 6e ........3..........poisoning,.an
2140 64 20 61 20 77 65 6c 6c 2d 64 65 66 69 6e 65 64 20 67 6f 73 73 69 70 20 70 72 6f 74 6f 63 6f 6c d.a.well-defined.gossip.protocol
2160 20 77 69 74 68 6f 75 74 20 63 6f 6d 70 6c 65 78 20 61 75 64 69 74 69 6e 67 20 6c 6f 67 69 63 2e .without.complex.auditing.logic.
2180 00 69 6e 63 6c 75 64 65 73 20 63 6f 6e 73 69 64 65 72 61 74 69 6f 6e 73 20 73 75 63 68 20 61 73 .includes.considerations.such.as
21a0 20 73 69 6d 70 6c 65 20 70 61 72 73 69 6e 67 2c 20 70 72 6f 74 65 63 74 69 6f 6e 20 61 67 61 69 .simple.parsing,.protection.agai
21c0 6e 73 74 20 6c 6f 67 20 73 70 61 6d 20 61 6e 64 00 65 78 61 6d 70 6c 65 20 6c 6f 67 20 6f 70 65 nst.log.spam.and.example.log.ope
21e0 72 61 74 69 6f 6e 73 20 61 6e 64 20 76 65 72 69 66 69 63 61 74 69 6f 6e 20 69 6e 20 63 6f 6e 73 rations.and.verification.in.cons
2200 74 72 61 69 6e 65 64 20 65 6e 76 69 72 6f 6e 6d 65 6e 74 73 2e 20 20 54 68 69 73 00 57 65 20 77 trained.environments...This.We.w
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2240 61 73 79 20 66 72 6f 6d 20 6d 61 6e 79 20 64 69 66 66 65 72 65 6e 74 20 70 65 72 73 70 65 63 74 asy.from.many.different.perspect
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22a0 65 74 61 64 61 74 61 20 69 73 20 61 20 6e 6f 6e 2d 67 6f 61 6c 2e 00 67 65 6e 65 72 61 6c 2e 20 etadata.is.a.non-goal..general..
22c0 20 54 68 65 72 65 66 6f 72 65 2c 20 73 69 67 73 75 6d 20 6c 6f 67 73 20 61 6c 6c 6f 77 20 6c 6f .Therefore,.sigsum.logs.allow.lo
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2320 74 6f 20 6d 61 6b 65 20 61 20 73 69 67 6e 65 72 27 73 20 6b 65 79 2d 75 73 61 67 65 20 74 72 61 to.make.a.signer's.key-usage.tra
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2360 6e 6f 6e 2d 73 63 6f 70 65 00 00 54 68 69 73 20 64 6f 63 75 6d 65 6e 74 20 69 73 20 61 62 6f 75 non-scope..This.document.is.abou
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23c0 6f 67 6c 65 2f 74 72 69 6c 6c 69 61 6e 2f 62 6c 6f 62 2f 6d 61 73 74 65 72 2f 64 6f 63 73 2f 63 ogle/trillian/blob/master/docs/c
23e0 6c 61 69 6d 61 6e 74 6d 6f 64 65 6c 2f 43 6f 72 65 4d 6f 64 65 6c 2e 6d 64 29 2e 00 75 73 69 6e laimantmodel/CoreModel.md)..usin
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2420 5d 28 68 74 74 70 73 3a 2f 2f 67 69 74 2e 73 69 67 73 75 6d 2e 6f 72 67 2f 73 69 67 73 75 6d 2f ](https://git.sigsum.org/sigsum/
2440 74 72 65 65 2f 64 6f 63 2f 63 6c 61 69 6d 61 6e 74 2e 6d 64 29 00 64 6f 63 75 6d 65 6e 74 20 74 tree/doc/claimant.md).document.t
2460 68 65 6d 20 62 61 73 65 64 20 6f 6e 20 77 68 61 74 20 70 65 6f 70 6c 65 20 61 72 65 20 77 6f 72 hem.based.on.what.people.are.wor
2480 6b 69 6e 67 20 6f 6e 20 69 6e 20 61 00 54 68 65 72 65 20 61 72 65 20 6d 61 6e 79 20 6f 74 68 65 king.on.in.a.There.are.many.othe
24a0 72 20 75 73 65 2d 63 61 73 65 73 20 74 68 61 74 20 73 69 67 73 75 6d 20 6c 6f 67 67 69 6e 67 20 r.use-cases.that.sigsum.logging.
24c0 63 61 6e 20 68 65 6c 70 20 77 69 74 68 2e 20 20 57 65 20 69 6e 74 65 6e 64 20 74 6f 00 00 09 5b can.help.with...We.intend.to...[
24e0 5c 5b 6e 75 73 65 6e 75 2d 64 72 61 66 74 5c 5d 5d 28 68 74 74 70 73 3a 2f 2f 67 69 74 6c 61 62 \[nusenu-draft\]](https://gitlab
2500 2e 74 6f 72 70 72 6f 6a 65 63 74 2e 6f 72 67 2f 6e 75 73 65 6e 75 2f 74 6f 72 73 70 65 63 2f 2d .torproject.org/nusenu/torspec/-
2520 2f 62 6c 6f 62 2f 73 69 6d 70 6c 65 2d 77 6f 74 2d 66 6f 72 2d 72 65 6c 61 79 2d 6f 70 65 72 61 /blob/simple-wot-for-relay-opera
2540 74 6f 72 2d 69 64 73 2f 70 72 6f 70 6f 73 61 6c 73 2f 69 64 65 61 73 2f 78 78 78 2d 73 69 6d 70 tor-ids/proposals/ideas/xxx-simp
2560 6c 65 2d 72 65 6c 61 79 2d 6f 70 65 72 61 74 6f 72 2d 77 6f 74 2e 6d 64 23 61 2d 73 69 6d 70 6c le-relay-operator-wot.md#a-simpl
2580 65 2d 77 65 62 2d 6f 66 2d 74 72 75 73 74 2d 66 6f 72 2d 74 6f 72 2d 72 65 6c 61 79 2d 6f 70 65 e-web-of-trust-for-tor-relay-ope
25a0 72 61 74 6f 72 2d 69 64 73 29 2e 00 2d 20 41 20 74 72 75 73 74 20 61 6e 63 68 6f 72 20 62 65 68 rator-ids)..-.A.trust.anchor.beh
25c0 61 76 65 73 20 61 63 63 6f 72 64 69 6e 67 20 74 6f 20 73 6f 6d 65 20 70 6f 6c 69 63 79 00 09 5b aves.according.to.some.policy..[
25e0 5c 5b 53 52 49 5c 5d 5d 28 68 74 74 70 73 3a 2f 2f 64 65 76 65 6c 6f 70 65 72 2e 6d 6f 7a 69 6c \[SRI\]](https://developer.mozil
2600 6c 61 2e 6f 72 67 2f 65 6e 2d 55 53 2f 64 6f 63 73 2f 57 65 62 2f 53 65 63 75 72 69 74 79 2f 53 la.org/en-US/docs/Web/Security/S
2620 75 62 72 65 73 6f 75 72 63 65 5f 49 6e 74 65 67 72 69 74 79 29 00 2d 20 41 20 64 6f 6d 61 69 6e ubresource_Integrity).-.A.domain
2640 20 64 6f 65 73 20 6e 6f 74 20 73 65 72 76 65 20 6d 61 6c 69 63 69 6f 75 73 20 6a 61 76 61 73 63 .does.not.serve.malicious.javasc
2660 72 69 70 74 00 09 5b 5c 5b 42 54 5c 5d 5d 28 68 74 74 70 73 3a 2f 2f 77 69 6b 69 2e 6d 6f 7a 69 ript..[\[BT\]](https://wiki.mozi
2680 6c 6c 61 2e 6f 72 67 2f 53 65 63 75 72 69 74 79 2f 42 69 6e 61 72 79 5f 54 72 61 6e 73 70 61 72 lla.org/Security/Binary_Transpar
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26c0 78 65 63 75 74 61 62 6c 65 20 62 69 6e 61 72 69 65 73 00 45 78 61 6d 70 6c 65 73 20 69 6e 63 6c xecutable.binaries.Examples.incl
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2700 66 61 63 69 6c 69 74 61 74 65 20 76 65 72 69 66 69 63 61 74 69 6f 6e 20 6f 66 20 66 61 6c 73 69 facilitate.verification.of.falsi
2720 66 69 61 62 6c 65 20 63 6c 61 69 6d 73 2e 00 69 64 65 61 20 69 73 20 74 6f 20 6d 61 6b 65 20 61 fiable.claims..idea.is.to.make.a
2740 20 73 69 67 6e 65 72 27 73 20 5f 6b 65 79 2d 75 73 61 67 65 5f 20 74 72 61 6e 73 70 61 72 65 6e .signer's._key-usage_.transparen
2760 74 2e 20 20 54 68 69 73 20 69 73 20 61 20 70 6f 77 65 72 66 75 6c 20 62 75 69 6c 64 69 6e 67 00 t...This.is.a.powerful.building.
2780 53 69 67 73 75 6d 20 6c 6f 67 73 20 6d 61 6b 65 20 69 74 20 70 6f 73 73 69 62 6c 65 20 74 6f 20 Sigsum.logs.make.it.possible.to.
27a0 61 6e 73 77 65 72 73 20 74 68 65 73 65 20 74 79 70 65 73 20 6f 66 20 71 75 65 73 74 69 6f 6e 73 answers.these.types.of.questions
27c0 2e 20 20 54 68 65 20 62 61 73 69 63 00 00 69 66 20 74 68 65 20 73 69 67 6e 69 6e 67 20 70 61 72 ...The.basic..if.the.signing.par
27e0 74 79 20 77 61 73 20 66 6f 72 63 65 64 20 74 6f 20 73 69 67 6e 20 6d 61 6c 69 63 69 6f 75 73 20 ty.was.forced.to.sign.malicious.
2800 64 61 74 61 20 61 67 61 69 6e 73 74 20 74 68 65 69 72 20 77 69 6c 6c 3f 00 48 6f 77 20 77 6f 75 data.against.their.will?.How.wou
2820 6c 64 20 77 65 20 64 65 74 65 63 74 20 69 66 20 73 6f 6d 65 74 68 69 6e 67 20 77 61 73 20 73 69 ld.we.detect.if.something.was.si
2840 67 6e 65 64 20 62 79 20 6d 69 73 74 61 6b 65 2c 20 6f 72 20 65 76 65 6e 20 77 6f 72 73 65 2c 00 gned.by.mistake,.or.even.worse,.
2860 48 6f 77 20 77 6f 75 6c 64 20 77 65 20 64 65 74 65 63 74 20 69 66 20 61 20 73 65 63 72 65 74 20 How.would.we.detect.if.a.secret.
2880 73 69 67 6e 69 6e 67 20 6b 65 79 20 67 6f 74 20 63 6f 6d 70 72 6f 6d 69 73 65 64 3f 00 77 68 65 signing.key.got.compromised?.whe
28a0 74 68 65 72 20 74 68 65 20 73 69 67 6e 65 64 20 64 61 74 61 20 69 73 20 5f 61 63 74 75 61 6c 6c ther.the.signed.data.is._actuall
28c0 79 20 74 68 65 20 64 61 74 61 20 74 68 61 74 20 73 68 6f 75 6c 64 20 68 61 76 65 20 62 65 65 6e y.the.data.that.should.have.been
28e0 20 73 69 67 6e 65 64 5f 2e 00 54 68 65 20 70 72 6f 62 6c 65 6d 20 77 69 74 68 20 5f 6a 75 73 74 .signed_..The.problem.with._just
2900 20 64 69 67 69 74 61 6c 20 73 69 67 6e 69 6e 67 5f 20 69 73 20 74 68 61 74 20 69 74 20 69 73 20 .digital.signing_.is.that.it.is.
2920 64 69 66 66 69 63 75 6c 74 20 74 6f 20 64 65 74 65 72 6d 69 6e 65 00 00 54 68 65 20 75 73 65 72 difficult.to.determine..The.user
2940 20 6f 66 20 74 68 65 20 73 69 67 6e 65 64 20 64 61 74 61 20 69 73 20 63 61 6c 6c 65 64 20 61 20 .of.the.signed.data.is.called.a.
2960 5f 76 65 72 69 66 69 65 72 5f 2e 00 54 68 65 20 73 69 67 6e 69 6e 67 20 70 61 72 74 79 20 69 73 _verifier_..The.signing.party.is
2980 20 63 61 6c 6c 65 64 20 61 20 5f 73 69 67 6e 65 72 5f 2e 00 73 69 67 73 75 6d 20 6c 6f 67 67 69 .called.a._signer_..sigsum.loggi
29a0 6e 67 20 61 73 20 70 72 65 2d 68 61 73 68 65 64 20 64 69 67 69 74 61 6c 20 73 69 67 6e 69 6e 67 ng.as.pre-hashed.digital.signing
29c0 20 77 69 74 68 20 74 72 61 6e 73 70 61 72 65 6e 63 79 2e 00 41 20 73 69 67 73 75 6d 20 6c 6f 67 .with.transparency..A.sigsum.log
29e0 20 62 72 69 6e 67 73 20 74 72 61 6e 73 70 61 72 65 6e 63 79 20 74 6f 20 2a 2a 73 69 67 2a 2a 6e .brings.transparency.to.**sig**n
2a00 65 64 20 63 68 65 63 6b 2a 2a 73 75 6d 2a 2a 73 2e 20 20 59 6f 75 20 63 61 6e 20 74 68 69 6e 6b ed.check**sum**s...You.can.think
2a20 20 6f 66 00 00 09 5b 5c 5b 41 75 64 69 74 4c 6f 67 5c 5d 5d 28 68 74 74 70 73 3a 2f 2f 74 72 61 .of...[\[AuditLog\]](https://tra
2a40 6e 73 70 61 72 65 6e 63 79 2e 64 65 76 2f 61 70 70 6c 69 63 61 74 69 6f 6e 2f 72 65 6c 69 61 62 nsparency.dev/application/reliab
2a60 6c 79 2d 6c 6f 67 2d 61 6c 6c 2d 61 63 74 69 6f 6e 73 2d 70 65 72 66 6f 72 6d 65 64 2d 6f 6e 2d ly-log-all-actions-performed-on-
2a80 79 6f 75 72 2d 73 65 72 76 65 72 73 2f 29 2e 00 6f 72 20 69 73 20 73 6f 6d 65 6f 6e 65 20 72 75 your-servers/)..or.is.someone.ru
2aa0 6e 6e 69 6e 67 20 75 6e 65 78 70 65 63 74 65 64 20 63 6f 6d 6d 61 6e 64 73 20 6f 6e 20 79 6f 75 nning.unexpected.commands.on.you
2ac0 72 20 73 65 72 76 65 72 00 09 5b 5c 5b 43 68 65 63 6b 73 75 6d 44 42 5c 5d 5d 28 68 74 74 70 73 r.server..[\[ChecksumDB\]](https
2ae0 3a 2f 2f 67 6f 2e 67 6f 6f 67 6c 65 73 6f 75 72 63 65 2e 63 6f 6d 2f 70 72 6f 70 6f 73 61 6c 2f ://go.googlesource.com/proposal/
2b00 2b 2f 6d 61 73 74 65 72 2f 64 65 73 69 67 6e 2f 32 35 35 33 30 2d 73 75 6d 64 62 2e 6d 64 29 2c +/master/design/25530-sumdb.md),
2b20 00 64 69 64 20 79 6f 75 20 67 65 74 20 61 20 64 69 66 66 65 72 65 6e 74 20 47 6f 20 6d 6f 64 75 .did.you.get.a.different.Go.modu
2b40 6c 65 20 74 68 61 6e 20 65 76 65 72 79 6f 6e 65 20 65 6c 73 65 00 09 5b 5c 5b 43 54 5c 5d 5d 28 le.than.everyone.else..[\[CT\]](
2b60 68 74 74 70 73 3a 2f 2f 74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67 2f 68 74 6d 6c 2f 72 66 63 36 https://tools.ietf.org/html/rfc6
2b80 39 36 32 29 2c 00 61 72 65 20 74 68 65 72 65 20 61 6e 79 20 28 6d 69 73 2d 29 69 73 73 75 65 64 962),.are.there.any.(mis-)issued
2ba0 20 54 4c 53 20 63 65 72 74 69 66 69 63 61 74 65 73 00 54 72 61 6e 73 70 61 72 65 6e 63 79 20 6c .TLS.certificates.Transparency.l
2bc0 6f 67 73 20 6d 61 6b 65 20 69 74 20 70 6f 73 73 69 62 6c 65 20 74 6f 20 64 65 74 65 63 74 20 75 ogs.make.it.possible.to.detect.u
2be0 6e 77 61 6e 74 65 64 20 65 76 65 6e 74 73 2e 20 20 46 6f 72 20 65 78 61 6d 70 6c 65 2c 00 23 23 nwanted.events...For.example,.##
2c00 20 31 20 2d 20 49 6e 74 72 6f 64 75 63 74 69 6f 6e 00 00 50 6c 65 61 73 65 20 6c 65 74 20 75 73 .1.-.Introduction..Please.let.us
2c20 20 6b 6e 6f 77 20 69 66 20 79 6f 75 20 68 61 76 65 20 61 6e 79 20 66 65 65 64 62 61 63 6b 2e 00 .know.if.you.have.any.feedback..
2c40 00 72 65 76 69 73 69 6f 6e 20 6f 66 20 74 68 69 73 20 64 6f 63 75 6d 65 6e 74 20 77 69 6c 6c 20 .revision.of.this.document.will.
2c60 62 75 6d 70 20 74 68 65 20 76 65 72 73 69 6f 6e 20 6e 75 6d 62 65 72 20 74 6f 20 76 31 2e 00 54 bump.the.version.number.to.v1..T
2c80 68 69 73 20 69 73 20 61 20 77 6f 72 6b 2d 69 6e 2d 70 72 6f 67 72 65 73 73 20 64 6f 63 75 6d 65 his.is.a.work-in-progress.docume
2ca0 6e 74 20 74 68 61 74 20 6d 61 79 20 62 65 20 6d 6f 76 65 64 20 6f 72 20 6d 6f 64 69 66 69 65 64 nt.that.may.be.moved.or.modified
2cc0 2e 20 20 41 20 66 75 74 75 72 65 00 2a 2a 57 61 72 6e 69 6e 67 2e 2a 2a 00 00 43 65 72 74 69 66 ...A.future.**Warning.**..Certif
2ce0 69 63 61 74 65 20 54 72 61 6e 73 70 61 72 65 6e 63 79 20 73 6f 6c 76 65 73 20 61 6e 64 20 68 6f icate.Transparency.solves.and.ho
2d00 77 2e 00 73 69 67 6e 61 74 75 72 65 73 2c 20 68 61 73 68 20 66 75 6e 63 74 69 6f 6e 73 2c 20 61 w..signatures,.hash.functions,.a
2d20 6e 64 20 4d 65 72 6b 6c 65 20 74 72 65 65 73 2e 20 20 59 6f 75 20 72 6f 75 67 68 6c 79 20 6b 6e nd.Merkle.trees...You.roughly.kn
2d40 6f 77 20 77 68 61 74 20 70 72 6f 62 6c 65 6d 00 59 6f 75 20 68 61 76 65 20 62 61 73 69 63 20 75 ow.what.problem.You.have.basic.u
2d60 6e 64 65 72 73 74 61 6e 64 69 6e 67 20 6f 66 20 63 72 79 70 74 6f 67 72 61 70 68 69 63 20 70 72 nderstanding.of.cryptographic.pr
2d80 69 6d 69 74 69 76 65 73 2c 20 65 2e 67 2e 2c 20 64 69 67 69 74 61 6c 00 2a 2a 50 72 65 6c 69 6d imitives,.e.g.,.digital.**Prelim
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2de0 65 73 20 61 72 6f 75 6e 64 20 63 65 6e 74 72 61 6c 69 7a 65 64 20 6c 6f 67 20 6f 70 65 72 61 74 es.around.centralized.log.operat
2e00 69 6f 6e 73 2c 20 64 69 73 74 72 69 62 75 74 65 64 20 74 72 75 73 74 2c 20 61 6e 64 00 6d 61 6e ions,.distributed.trust,.and.man
2e20 61 67 65 6d 65 6e 74 20 6f 66 20 65 78 65 63 75 74 61 62 6c 65 20 62 69 6e 61 72 69 65 73 20 61 agement.of.executable.binaries.a
2e40 6e 64 20 70 72 6f 76 65 6e 61 6e 63 65 20 61 72 65 20 74 77 6f 20 65 78 61 6d 70 6c 65 73 2e 20 nd.provenance.are.two.examples..
2e60 20 4f 75 72 00 61 20 62 75 69 6c 64 69 6e 67 20 62 6c 6f 63 6b 20 74 68 61 74 20 63 61 6e 20 62 .Our.a.building.block.that.can.b
2e80 65 20 75 73 65 64 20 66 6f 72 20 61 20 76 61 72 69 65 74 79 20 6f 66 20 75 73 65 2d 63 61 73 65 e.used.for.a.variety.of.use-case
2ea0 73 2e 20 20 54 72 61 6e 73 70 61 72 65 6e 74 00 6d 61 6c 69 63 69 6f 75 73 20 61 6e 64 20 75 6e s...Transparent.malicious.and.un
2ec0 69 6e 74 65 6e 64 65 64 20 6b 65 79 2d 75 73 61 67 65 20 63 61 6e 20 62 65 20 64 65 74 65 63 74 intended.key-usage.can.be.detect
2ee0 65 64 20 75 73 69 6e 67 20 61 20 73 69 67 73 75 6d 20 6c 6f 67 2e 20 20 54 68 69 73 20 69 73 00 ed.using.a.sigsum.log...This.is.
2f00 6c 6f 67 67 65 64 20 69 6e 20 6f 72 64 65 72 20 74 6f 20 6d 61 6b 65 20 73 69 67 6e 61 74 75 72 logged.in.order.to.make.signatur
2f20 65 20 6f 70 65 72 61 74 69 6f 6e 73 20 74 72 61 6e 73 70 61 72 65 6e 74 2e 20 20 46 6f 72 20 65 e.operations.transparent...For.e
2f40 78 61 6d 70 6c 65 2c 00 63 68 65 63 6b 73 75 6d 20 64 61 74 61 62 61 73 65 2c 20 65 78 63 65 70 xample,.checksum.database,.excep
2f60 74 20 74 68 61 74 20 63 72 79 70 74 6f 67 72 61 70 68 69 63 61 6c 6c 79 20 2a 2a 73 69 67 2a 2a t.that.cryptographically.**sig**
2f80 6e 65 64 20 63 68 65 63 6b 2a 2a 73 75 6d 2a 2a 73 20 61 72 65 00 57 65 20 70 72 6f 70 6f 73 65 ned.check**sum**s.are.We.propose
2fa0 20 73 69 67 73 75 6d 20 6c 6f 67 67 69 6e 67 2e 20 20 49 74 20 69 73 20 73 69 6d 69 6c 61 72 20 .sigsum.logging...It.is.similar.
2fc0 74 6f 20 43 65 72 74 69 66 69 63 61 74 65 20 54 72 61 6e 73 70 61 72 65 6e 63 79 20 61 6e 64 20 to.Certificate.Transparency.and.
2fe0 47 6f 27 73 00 23 20 53 69 67 73 75 6d 20 4c 6f 67 67 69 6e 67 20 44 65 73 69 67 6e 20 76 30 00 Go's.#.Sigsum.Logging.Design.v0.
3000 61 64 00 00 b9 05 00 00 81 06 00 00 00 10 00 00 2b 00 00 00 00 00 00 00 b2 0f 00 00 b1 0f 00 00 ad..............+...............
3020 65 0f 00 00 17 0f 00 00 c9 0e 00 00 79 0e 00 00 78 0e 00 00 55 0e 00 00 14 0e 00 00 e9 0d 00 00 e...........y...x...U...........
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3060 57 0b 00 00 0a 0b 00 00 e7 0a 00 00 e6 0a 00 00 99 0a 00 00 52 0a 00 00 0f 0a 00 00 0e 0a 00 00 W...................R...........
3080 bd 09 00 00 bc 09 00 00 6e 09 00 00 1e 09 00 00 e0 08 00 00 82 08 00 00 81 08 00 00 72 08 00 00 ........n...................r...
30a0 32 08 00 00 ea 07 00 00 b5 07 00 00 7e 07 00 00 2e 07 00 00 f3 06 00 00 d1 06 00 00 a6 06 00 00 2...........~...................
30c0 81 06 00 00 80 06 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
30e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3100 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3120 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3140 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3160 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3180 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
31a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
31c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
31e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3200 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3220 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3240 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3260 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3280 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
32a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
32c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
32e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3300 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3320 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3340 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3360 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3380 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
33a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
33c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
33e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3400 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3420 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3440 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3460 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3480 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
34a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
34c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
34e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3500 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3520 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3540 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3560 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3580 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
35a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
35c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
35e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3600 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3620 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3640 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3660 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
3680 00 2d 20 57 68 61 74 20 70 6f 6c 69 63 79 20 73 68 6f 75 6c 64 20 61 20 62 65 6c 69 65 76 65 72 .-.What.policy.should.a.believer
36a0 20 75 73 65 3f 00 2d 20 48 6f 77 20 64 6f 65 73 20 69 74 20 77 6f 72 6b 20 77 69 74 68 20 6d 6f .use?.-.How.does.it.work.with.mo
36c0 72 65 20 74 68 61 6e 20 6f 6e 65 20 6c 6f 67 3f 00 2d 20 41 72 65 20 74 68 65 72 65 20 61 6e 79 re.than.one.log?.-.Are.there.any
36e0 20 70 72 69 76 61 63 79 20 63 6f 6e 63 65 72 6e 73 3f 00 73 68 6f 75 6c 64 20 69 6e 63 6c 75 64 .privacy.concerns?.should.includ
3700 65 20 60 67 65 74 2d 74 72 65 65 2d 68 65 61 64 2d 2a 60 20 65 6e 64 70 6f 69 6e 74 73 20 69 6e e.`get-tree-head-*`.endpoints.in
3720 20 6d 6f 72 65 20 64 65 74 61 69 6c 2e 00 2d 20 57 68 61 74 20 74 68 6f 75 67 68 74 20 77 65 6e .more.detail..-.What.thought.wen
3740 74 20 69 6e 74 6f 20 77 69 74 6e 65 73 73 20 63 6f 73 69 67 6e 69 6e 67 3f 20 20 43 6f 6d 70 61 t.into.witness.cosigning?..Compa
3760 72 65 20 77 69 74 68 20 6f 74 68 65 72 20 61 70 70 72 6f 61 63 68 65 73 2c 20 61 6e 64 00 2d 20 re.with.other.approaches,.and.-.
3780 57 68 61 74 20 63 72 79 70 74 6f 67 72 61 70 68 69 63 20 70 72 69 6d 69 74 69 76 65 73 20 61 72 What.cryptographic.primitives.ar
37a0 65 20 73 75 70 70 6f 72 74 65 64 20 61 6e 64 20 77 68 79 3f 00 2d 20 57 68 61 74 20 28 64 65 29 e.supported.and.why?.-.What.(de)
37c0 73 65 72 69 61 6c 69 7a 61 74 69 6f 6e 20 70 61 72 73 65 72 73 20 61 72 65 20 6e 65 65 64 65 64 serialization.parsers.are.needed
37e0 20 61 6e 64 20 77 68 79 3f 00 2d 20 57 68 79 20 6e 6f 74 20 73 74 6f 72 65 20 72 69 63 68 20 6d .and.why?.-.Why.not.store.rich.m
3800 65 74 61 64 61 74 61 20 69 6e 20 74 68 65 20 6c 6f 67 3f 20 58 58 58 3a 20 61 6e 73 77 65 72 65 etadata.in.the.log?.XXX:.answere
3820 64 20 65 6e 6f 75 67 68 20 61 6c 72 65 61 64 79 3f 00 2d 20 57 68 79 20 6e 6f 74 20 73 74 6f 72 d.enough.already?.-.Why.not.stor
3840 65 20 64 61 74 61 20 69 6e 20 74 68 65 20 6c 6f 67 3f 20 20 58 58 58 3a 20 61 6e 73 77 65 72 65 e.data.in.the.log?..XXX:.answere
3860 64 20 65 6e 6f 75 67 68 20 61 6c 72 65 61 64 79 3f 00 23 23 23 23 20 34 2e 33 20 2d 20 58 58 58 d.enough.already?.####.4.3.-.XXX
3880 00 00 09 5b 5c 5b 54 53 5c 5d 5d 28 68 74 74 70 73 3a 2f 2f 67 69 74 2e 73 69 67 73 75 6d 2e 6f ...[\[TS\]](https://git.sigsum.o
38a0 72 67 2f 73 69 67 73 75 6d 2f 63 6f 6d 6d 69 74 2f 3f 69 64 3d 66 65 66 34 36 30 35 38 36 65 38 rg/sigsum/commit/?id=fef460586e8
38c0 34 37 65 33 37 38 61 31 39 37 33 38 31 65 66 31 61 65 33 61 36 34 65 36 65 61 33 38 62 29 2e 00 47e378a197381ef1ae3a64e6ea38b)..
38e0 74 68 65 20 74 69 6d 65 20 6f 66 20 6c 6f 67 67 69 6e 67 2c 20 79 6f 75 20 6d 61 79 20 75 73 65 the.time.of.logging,.you.may.use
3900 20 61 20 63 6f 73 69 67 6e 65 64 20 74 72 65 65 20 68 65 61 64 20 69 6e 73 74 65 61 64 00 73 65 .a.cosigned.tree.head.instead.se
3920 74 20 69 74 20 61 73 20 6c 61 72 67 65 20 61 73 20 70 6f 73 73 69 62 6c 65 2e 20 20 49 66 20 61 t.it.as.large.as.possible...If.a
3940 20 76 65 72 69 66 69 65 64 20 74 69 6d 65 73 74 61 6d 70 20 69 73 20 6e 65 65 64 65 64 20 74 6f .verified.timestamp.is.needed.to
3960 20 72 65 61 73 6f 6e 20 61 62 6f 75 74 00 4e 6f 74 65 20 74 68 61 74 20 61 20 73 69 67 6e 65 72 .reason.about.Note.that.a.signer
3980 27 73 20 73 68 61 72 64 20 68 69 6e 74 20 69 73 20 6e 6f 74 20 61 20 76 65 72 69 66 69 65 64 20 's.shard.hint.is.not.a.verified.
39a0 74 69 6d 65 73 74 61 6d 70 2e 20 20 57 65 20 72 65 63 6f 6d 6d 65 6e 64 20 74 6f 00 00 53 75 63 timestamp...We.recommend.to..Suc
39c0 68 20 72 65 2d 6c 6f 67 67 69 6e 67 20 61 6c 73 6f 20 63 6f 6d 65 73 20 61 74 20 74 68 65 20 72 h.re-logging.also.comes.at.the.r
39e0 69 73 6b 20 6f 66 20 61 63 74 69 76 61 74 69 6e 67 20 73 6f 6d 65 6f 6e 65 20 65 6c 73 65 27 73 isk.of.activating.someone.else's
3a00 20 72 61 74 65 20 6c 69 6d 69 74 73 2e 00 00 75 6e 73 75 73 74 61 69 6e 61 62 6c 65 20 69 6e 20 .rate.limits...unsustainable.in.
3a20 74 68 65 20 6c 6f 6e 67 20 72 75 6e 20 62 65 63 61 75 73 65 20 6c 6f 67 20 73 69 7a 65 73 20 67 the.long.run.because.log.sizes.g
3a40 72 6f 77 20 69 6e 64 65 66 69 6e 69 74 65 6c 79 2e 00 6e 65 77 65 72 20 6f 6e 65 20 74 68 61 74 row.indefinitely..newer.one.that
3a60 20 6a 75 73 74 20 73 74 61 72 74 65 64 20 69 74 73 20 6f 70 65 72 61 74 69 6f 6e 73 2e 20 20 54 .just.started.its.operations...T
3a80 68 69 73 20 6d 61 6b 65 73 20 6c 6f 67 20 6f 70 65 72 61 74 69 6f 6e 73 00 57 69 74 68 6f 75 74 his.makes.log.operations.Without
3aa0 20 73 68 61 72 64 69 6e 67 2c 20 61 20 67 6f 6f 64 20 53 61 6d 61 72 69 74 61 6e 20 63 61 6e 20 .sharding,.a.good.Samaritan.can.
3ac0 61 64 64 20 61 6c 6c 20 6c 65 61 76 65 73 20 66 72 6f 6d 20 61 6e 20 6f 6c 64 20 6c 6f 67 20 69 add.all.leaves.from.an.old.log.i
3ae0 6e 74 6f 20 61 00 00 65 70 6f 63 68 20 28 4a 61 6e 75 61 72 79 20 31 2c 20 31 39 37 30 20 30 30 nto.a..epoch.(January.1,.1970.00
3b00 3a 30 30 20 55 54 43 29 2e 00 69 6e 74 65 72 76 61 6c 20 61 72 65 20 69 6e 63 6c 75 73 69 76 65 :00.UTC)..interval.are.inclusive
3b20 20 61 6e 64 20 65 78 70 72 65 73 73 65 64 20 61 73 20 74 68 65 20 6e 75 6d 62 65 72 20 6f 66 20 .and.expressed.as.the.number.of.
3b40 73 65 63 6f 6e 64 73 20 73 69 6e 63 65 20 74 68 65 20 55 4e 49 58 00 69 6e 74 65 72 76 61 6c 20 seconds.since.the.UNIX.interval.
3b60 69 73 20 64 65 66 69 6e 65 64 20 62 79 20 61 20 73 74 61 72 74 20 74 69 6d 65 20 61 6e 64 20 61 is.defined.by.a.start.time.and.a
3b80 6e 20 65 6e 64 20 74 69 6d 65 2e 20 20 42 6f 74 68 20 65 6e 64 73 20 6f 66 20 74 68 65 20 73 68 n.end.time...Both.ends.of.the.sh
3ba0 61 72 64 00 73 68 61 72 64 20 68 69 6e 74 2e 20 20 54 68 65 20 73 65 6c 65 63 74 65 64 20 73 68 ard.shard.hint...The.selected.sh
3bc0 61 72 64 20 68 69 6e 74 20 6d 75 73 74 20 62 65 20 69 6e 20 61 20 6c 6f 67 27 73 20 73 68 61 72 ard.hint.must.be.in.a.log's.shar
3be0 64 20 69 6e 74 65 72 76 61 6c 2e 20 20 41 20 73 68 61 72 64 00 63 61 72 72 79 20 61 6e 79 20 73 d.interval...A.shard.carry.any.s
3c00 75 63 68 20 69 6e 66 6f 72 6d 61 74 69 6f 6e 2e 20 20 54 68 65 72 65 66 6f 72 65 2c 20 77 65 20 uch.information...Therefore,.we.
3c20 72 65 71 75 69 72 65 20 74 68 61 74 20 74 68 65 20 73 69 67 6e 65 72 20 73 65 6c 65 63 74 73 20 require.that.the.signer.selects.
3c40 61 00 55 6e 6c 69 6b 65 20 54 4c 53 20 63 65 72 74 69 66 69 63 61 74 65 73 20 77 68 69 63 68 20 a.Unlike.TLS.certificates.which.
3c60 61 6c 72 65 61 64 79 20 68 61 76 65 20 76 61 6c 69 64 69 74 79 20 72 61 6e 67 65 73 2c 20 61 20 already.have.validity.ranges,.a.
3c80 63 68 65 63 6b 73 75 6d 20 64 6f 65 73 20 6e 6f 74 00 23 23 23 23 20 34 2e 32 20 2d 20 57 68 61 checksum.does.not.####.4.2.-.Wha
3ca0 74 20 69 73 20 74 68 65 20 70 6f 69 6e 74 20 6f 66 20 68 61 76 69 6e 67 20 61 20 73 68 61 72 64 t.is.the.point.of.having.a.shard
3cc0 20 68 69 6e 74 3f 00 00 61 62 6f 75 74 2e 20 20 57 65 20 61 72 65 20 73 74 69 6c 6c 20 6f 70 65 .hint?..about...We.are.still.ope
3ce0 6e 20 74 6f 20 72 65 6d 6f 76 65 2c 20 61 64 64 2c 20 6f 72 20 63 68 61 6e 67 65 20 74 68 69 6e n.to.remove,.add,.or.change.thin
3d00 67 73 20 69 66 20 69 74 20 69 73 20 6d 6f 74 69 76 61 74 65 64 2e 00 49 74 20 6d 61 79 20 62 65 gs.if.it.is.motivated..It.may.be
3d20 20 69 6e 63 6f 6d 70 6c 65 74 65 2c 20 62 75 74 20 63 6f 76 65 72 73 20 73 6f 6d 65 20 64 65 74 .incomplete,.but.covers.some.det
3d40 61 69 6c 73 20 74 68 61 74 20 61 72 65 20 77 6f 72 74 68 20 74 68 69 6e 6b 69 6e 67 20 6d 6f 72 ails.that.are.worth.thinking.mor
3d60 65 00 09 5b 32 30 32 31 2d 31 30 2d 30 35 5d 28 68 74 74 70 73 3a 2f 2f 67 69 74 2e 73 69 67 73 e..[2021-10-05](https://git.sigs
3d80 75 6d 2e 6f 72 67 2f 73 69 67 73 75 6d 2f 74 72 65 65 2f 61 72 63 68 69 76 65 2f 32 30 32 31 2d um.org/sigsum/tree/archive/2021-
3da0 31 30 2d 30 35 2d 6f 70 65 6e 2d 64 65 73 69 67 6e 2d 74 68 6f 75 67 68 74 73 3f 69 64 3d 35 63 10-05-open-design-thoughts?id=5c
3dc0 30 32 37 37 30 62 35 62 64 37 64 34 33 62 39 33 32 37 36 32 33 64 33 64 65 39 61 64 65 64 61 32 02770b5bd7d43b9327623d3de9adeda2
3de0 34 36 38 65 38 34 29 2e 00 41 20 62 72 69 65 66 20 73 75 6d 6d 61 72 79 20 61 70 70 65 61 72 65 468e84)..A.brief.summary.appeare
3e00 64 20 69 6e 20 6f 75 72 20 61 72 63 68 69 76 65 20 6f 6e 00 23 23 23 23 20 34 2e 31 20 2d 20 57 d.in.our.archive.on.####.4.1.-.W
3e20 68 61 74 20 70 61 72 74 73 20 6f 66 20 74 68 65 20 64 65 73 69 67 6e 20 61 72 65 20 77 65 20 73 hat.parts.of.the.design.are.we.s
3e40 74 69 6c 6c 20 74 68 69 6e 6b 69 6e 67 20 61 62 6f 75 74 3f 00 23 23 23 20 34 20 2d 20 46 72 65 till.thinking.about?.###.4.-.Fre
3e60 71 75 65 6e 74 6c 79 20 41 73 6b 65 64 20 51 75 65 73 74 69 6f 6e 73 00 00 63 68 65 63 6b 73 75 quently.Asked.Questions..checksu
3e80 6d 73 20 69 6e 20 74 68 65 20 6c 6f 67 73 2c 20 67 65 6e 65 72 61 74 69 6e 67 20 61 6c 65 72 74 ms.in.the.logs,.generating.alert
3ea0 73 20 69 66 20 75 73 65 2d 63 61 73 65 20 73 70 65 63 69 66 69 63 20 63 6c 61 69 6d 73 20 61 72 s.if.use-case.specific.claims.ar
3ec0 65 20 66 61 6c 73 65 2e 00 61 6e 64 20 64 69 73 74 72 69 62 75 74 69 6e 67 20 6e 65 63 65 73 73 e.false..and.distributing.necess
3ee0 61 72 79 20 70 72 6f 6f 66 73 20 6f 66 20 70 75 62 6c 69 63 20 6c 6f 67 67 69 6e 67 2e 20 20 4d ary.proofs.of.public.logging...M
3f00 6f 6e 69 74 6f 72 20 64 69 73 63 6f 76 65 72 20 73 69 67 6e 65 64 00 64 69 73 74 72 69 62 75 74 onitor.discover.signed.distribut
3f20 69 6f 6e 20 6d 65 63 68 61 6e 69 73 6d 2e 20 20 53 69 67 6e 65 72 73 20 61 72 65 20 72 65 73 70 ion.mechanism...Signers.are.resp
3f40 6f 6e 73 69 62 6c 65 20 66 6f 72 20 6c 6f 67 67 69 6e 67 20 73 69 67 6e 65 64 20 63 68 65 63 6b onsible.for.logging.signed.check
3f60 73 75 6d 73 00 56 65 72 69 66 69 65 72 73 20 69 6e 74 65 72 61 63 74 20 77 69 74 68 20 74 68 65 sums.Verifiers.interact.with.the
3f80 20 6c 6f 67 73 20 69 6e 64 69 72 65 63 74 6c 79 20 74 68 72 6f 75 67 68 20 74 68 65 69 72 20 73 .logs.indirectly.through.their.s
3fa0 69 67 6e 65 72 27 73 20 65 78 69 73 74 69 6e 67 00 00 49 74 20 61 6c 73 6f 20 6b 65 65 70 73 20 igner's.existing..It.also.keeps.
3fc0 6c 6f 67 20 6f 70 65 72 61 74 69 6f 6e 73 20 73 69 6d 70 6c 65 72 20 62 65 63 61 75 73 65 20 74 log.operations.simpler.because.t
3fe0 68 65 72 65 20 61 72 65 20 66 65 77 65 72 20 62 79 74 65 73 20 74 6f 20 6d 61 6e 61 67 65 2e 00 here.are.fewer.bytes.to.manage..
4000 61 64 00 00 8a 0d 00 00 ca 0d 00 00 00 10 00 00 09 00 00 00 00 00 00 00 b1 0f 00 00 6a 0f 00 00 ad..........................j...
4020 59 0f 00 00 04 0f 00 00 03 0f 00 00 b4 0e 00 00 66 0e 00 00 16 0e 00 00 ca 0d 00 00 bf 0d 00 00 Y...............f...............
4040 be 0d 00 00 72 0d 00 00 28 0d 00 00 de 0c 00 00 d5 0c 00 00 85 0c 00 00 81 0c 00 00 28 0c 00 00 ....r...(...................(...
4060 dd 0b 00 00 dc 0b 00 00 ce 0b 00 00 80 0b 00 00 62 0b 00 00 5e 0b 00 00 32 0b 00 00 f5 0a 00 00 ................b...^...2.......
4080 b4 0a 00 00 76 0a 00 00 3e 0a 00 00 fd 09 00 00 bc 09 00 00 7b 09 00 00 43 09 00 00 07 09 00 00 ....v...>...........{...C.......
40a0 c7 08 00 00 8a 08 00 00 52 08 00 00 12 08 00 00 d2 07 00 00 92 07 00 00 6b 07 00 00 3f 07 00 00 ........R...............k...?...
40c0 33 07 00 00 02 07 00 00 fe 06 00 00 fd 06 00 00 b1 06 00 00 63 06 00 00 15 06 00 00 c7 05 00 00 3...................c...........
40e0 7b 05 00 00 7a 05 00 00 29 05 00 00 db 04 00 00 90 04 00 00 44 04 00 00 43 04 00 00 fa 03 00 00 {...z...)...........D...C.......
4100 aa 03 00 00 5c 03 00 00 0b 03 00 00 0a 03 00 00 bd 02 00 00 6e 02 00 00 2f 02 00 00 2e 02 00 00 ....\...............n.../.......
4120 18 02 00 00 c8 01 00 00 78 01 00 00 3a 01 00 00 38 01 00 00 00 00 00 00 00 64 64 69 73 74 72 69 ........x...:...8........ddistri
4140 62 75 74 65 64 20 66 6f 72 6d 20 6f 66 20 74 72 75 73 74 2e 20 20 41 20 74 72 65 65 20 6c 65 61 buted.form.of.trust...A.tree.lea
4160 66 20 63 6f 6e 74 61 69 6e 73 20 66 6f 75 72 20 66 69 65 6c 64 73 3a 00 76 65 72 69 66 79 20 74 f.contains.four.fields:.verify.t
4180 68 61 74 20 74 68 69 73 20 74 72 65 65 20 69 73 20 66 72 65 73 68 20 61 6e 64 20 61 70 70 65 6e hat.this.tree.is.fresh.and.appen
41a0 64 2d 6f 6e 6c 79 20 62 65 66 6f 72 65 20 63 6f 73 69 67 6e 69 6e 67 20 69 74 20 74 6f 20 61 63 d-only.before.cosigning.it.to.ac
41c0 68 69 65 76 65 20 61 00 41 20 73 69 67 73 75 6d 20 6c 6f 67 20 6d 61 69 6e 74 61 69 6e 73 20 61 hieve.a.A.sigsum.log.maintains.a
41e0 20 70 75 62 6c 69 63 20 61 70 70 65 6e 64 2d 6f 6e 6c 79 20 4d 65 72 6b 6c 65 20 74 72 65 65 2e .public.append-only.Merkle.tree.
4200 20 20 49 6e 64 65 70 65 6e 64 65 6e 74 20 77 69 74 6e 65 73 73 65 73 00 23 23 23 20 33 2e 31 20 ..Independent.witnesses.###.3.1.
4220 2d 20 4d 65 72 6b 6c 65 20 74 72 65 65 00 00 63 6f 73 69 67 6e 69 6e 67 20 70 72 6f 74 6f 63 6f -.Merkle.tree..cosigning.protoco
4240 6c 2e 20 20 4d 6f 72 65 20 64 65 74 61 69 6c 20 69 73 20 70 72 6f 76 69 64 65 64 20 69 6e 20 53 l...More.detail.is.provided.in.S
4260 65 63 74 69 6f 6e 20 33 2e 32 2e 33 2e 00 61 64 64 69 74 69 6f 6e 61 6c 20 6f 75 74 62 6f 75 6e ection.3.2.3..additional.outboun
4280 64 20 6e 65 74 77 6f 72 6b 20 63 6f 6e 6e 65 63 74 69 6f 6e 73 20 69 66 20 61 20 74 68 72 65 73 d.network.connections.if.a.thres
42a0 68 6f 6c 64 20 6f 66 20 77 69 74 6e 65 73 73 65 73 20 66 6f 6c 6c 6f 77 65 64 20 61 00 56 65 72 hold.of.witnesses.followed.a.Ver
42c0 69 66 69 65 72 73 20 61 6e 64 20 6d 6f 6e 69 74 6f 72 73 20 63 61 6e 20 62 65 20 63 6f 6e 76 69 ifiers.and.monitors.can.be.convi
42e0 6e 63 65 64 20 74 68 61 74 20 70 75 62 6c 69 63 20 6c 6f 67 67 69 6e 67 20 68 61 70 70 65 6e 65 nced.that.public.logging.happene
4300 64 20 77 69 74 68 6f 75 74 00 00 74 68 65 69 72 20 6b 65 79 2d 75 73 61 67 65 20 63 61 6e 20 6e d.without..their.key-usage.can.n
4320 6f 77 20 62 65 20 76 65 72 69 66 69 65 64 20 62 65 63 61 75 73 65 20 6e 6f 20 73 69 67 6e 69 6e ow.be.verified.because.no.signin
4340 67 20 6f 70 65 72 61 74 69 6f 6e 20 67 6f 65 73 20 75 6e 6e 6f 74 69 63 65 64 2e 00 6b 65 79 73 g.operation.goes.unnoticed..keys
4360 20 74 68 61 74 20 74 68 65 79 20 61 72 65 20 61 77 61 72 65 20 6f 66 2e 20 20 41 6e 79 20 66 61 .that.they.are.aware.of...Any.fa
4380 6c 73 69 66 69 61 62 6c 65 20 63 6c 61 69 6d 20 74 68 61 74 20 61 20 73 69 67 6e 65 72 20 6d 61 lsifiable.claim.that.a.signer.ma
43a0 6b 65 73 20 61 62 6f 75 74 00 6c 6f 67 67 69 6e 67 2e 20 20 4d 6f 6e 69 74 6f 72 73 20 6c 6f 6f kes.about.logging...Monitors.loo
43c0 6b 20 66 6f 72 20 73 69 67 6e 65 64 20 63 68 65 63 6b 73 75 6d 73 20 61 6e 64 20 64 61 74 61 20 k.for.signed.checksums.and.data.
43e0 74 68 61 74 20 63 6f 72 72 65 73 70 6f 6e 64 20 74 6f 20 70 75 62 6c 69 63 00 56 65 72 69 66 69 that.correspond.to.public.Verifi
4400 65 72 73 20 75 73 65 20 74 68 65 20 73 69 67 6e 65 72 27 73 20 64 61 74 61 20 69 66 20 69 74 20 ers.use.the.signer's.data.if.it.
4420 69 73 20 61 63 63 6f 6d 70 61 6e 69 65 64 20 62 79 20 70 72 6f 6f 66 73 20 6f 66 20 70 75 62 6c is.accompanied.by.proofs.of.publ
4440 69 63 00 00 6c 6f 67 67 69 6e 67 2e 20 20 41 20 73 69 67 73 75 6d 20 6c 6f 67 20 64 6f 65 73 20 ic..logging...A.sigsum.log.does.
4460 6e 6f 74 20 68 65 6c 70 20 74 68 65 20 73 69 67 6e 65 72 20 77 69 74 68 20 61 6e 79 20 64 61 74 not.help.the.signer.with.any.dat
4480 61 20 64 69 73 74 72 69 62 75 74 69 6f 6e 2e 00 74 68 65 20 73 69 67 6e 65 64 20 63 68 65 63 6b a.distribution..the.signed.check
44a0 73 75 6d 27 73 20 64 61 74 61 20 69 73 20 72 65 61 64 79 20 66 6f 72 20 64 69 73 74 72 69 62 75 sum's.data.is.ready.for.distribu
44c0 74 69 6f 6e 20 77 69 74 68 20 70 72 6f 6f 66 73 20 6f 66 20 70 75 62 6c 69 63 00 69 6e 63 6c 75 tion.with.proofs.of.public.inclu
44e0 73 69 6f 6e 20 70 72 6f 6f 66 20 69 73 20 61 76 61 69 6c 61 62 6c 65 20 74 68 61 74 20 6c 65 61 sion.proof.is.available.that.lea
4500 64 73 20 75 70 20 74 6f 20 61 20 74 72 75 73 74 77 6f 72 74 68 79 20 4d 65 72 6b 6c 65 20 74 72 ds.up.to.a.trustworthy.Merkle.tr
4520 65 65 20 68 65 61 64 2c 00 54 68 65 20 73 69 67 6e 69 6e 67 20 70 61 72 74 79 20 77 61 69 74 73 ee.head,.The.signing.party.waits
4540 20 66 6f 72 20 74 68 65 69 72 20 73 75 62 6d 69 73 73 69 6f 6e 20 74 6f 20 62 65 20 69 6e 63 6c .for.their.submission.to.be.incl
4560 75 64 65 64 20 69 6e 20 74 68 65 20 6c 6f 67 2e 20 20 57 68 65 6e 20 61 6e 00 00 6b 65 79 20 69 uded.in.the.log...When.an..key.i
4580 73 20 63 6f 6e 66 69 67 75 72 65 64 20 69 6e 20 44 4e 53 20 61 73 20 61 20 54 58 54 20 72 65 63 s.configured.in.DNS.as.a.TXT.rec
45a0 6f 72 64 20 74 6f 20 68 65 6c 70 20 6c 6f 67 20 6f 70 65 72 61 74 6f 72 73 20 63 6f 6d 62 61 74 ord.to.help.log.operators.combat
45c0 20 73 70 61 6d 2e 00 61 6e 64 20 61 20 68 61 73 68 20 6f 66 20 74 68 65 20 70 75 62 6c 69 63 20 .spam..and.a.hash.of.the.public.
45e0 76 65 72 69 66 69 63 61 74 69 6f 6e 20 6b 65 79 2e 20 20 41 20 68 61 73 68 20 6f 66 20 74 68 65 verification.key...A.hash.of.the
4600 20 70 75 62 6c 69 63 20 76 65 72 69 66 69 63 61 74 69 6f 6e 00 64 61 74 61 2e 20 20 4d 69 6e 69 .public.verification.data...Mini
4620 6d 61 6c 20 6d 65 74 61 64 61 74 61 20 6d 75 73 74 20 61 6c 73 6f 20 62 65 20 6c 6f 67 67 65 64 mal.metadata.must.also.be.logged
4640 2c 20 73 75 63 68 20 61 73 20 74 68 65 20 63 68 65 63 6b 73 75 6d 27 73 20 73 69 67 6e 61 74 75 ,.such.as.the.checksum's.signatu
4660 72 65 00 73 74 61 74 65 6d 65 6e 74 20 74 68 61 74 20 73 69 67 73 75 6d 20 6c 6f 67 73 20 61 63 re.statement.that.sigsum.logs.ac
4680 63 65 70 74 2e 20 20 54 68 61 74 20 73 74 61 74 65 6d 65 6e 74 20 65 6e 63 6f 64 65 73 20 61 20 cept...That.statement.encodes.a.
46a0 63 68 65 63 6b 73 75 6d 20 6f 66 20 73 6f 6d 65 00 41 20 73 69 67 6e 65 72 20 77 61 6e 74 73 20 checksum.of.some.A.signer.wants.
46c0 74 6f 20 6d 61 6b 65 20 74 68 65 69 72 20 6b 65 79 2d 75 73 61 67 65 20 74 72 61 6e 73 70 61 72 to.make.their.key-usage.transpar
46e0 65 6e 74 2e 20 20 54 68 65 72 65 66 6f 72 65 2c 20 74 68 65 79 20 73 69 67 6e 20 61 00 00 60 60 ent...Therefore,.they.sign.a..``
4700 60 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 46 69 67 75 72 65 20 `........................Figure.
4720 31 3a 20 73 79 73 74 65 6d 20 6f 76 65 72 76 69 65 77 00 20 20 20 20 20 20 20 20 20 20 20 00 20 1:.system.overview..............
4740 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 69 ...............................i
4760 6e 76 65 73 74 69 67 61 74 65 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 nvestigate......................
4780 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 76 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 ................v...............
47a0 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 20 20 20 20 20 20 20 20 20 20 20 7c 20 63 6c 61 69 6d 20 20 .+---------+...........|.claim..
47c0 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 .....+----------+...............
47e0 20 7c 20 77 69 74 6e 65 73 73 20 7c 20 20 20 20 20 20 20 20 20 20 20 7c 20 66 61 6c 73 65 20 20 .|.witness.|...........|.false..
4800 20 20 20 20 20 7c 20 56 65 72 69 66 69 65 72 20 7c 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 .....|.Verifier.|...............
4820 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 20 20 20 20 20 20 20 20 20 20 20 7c 20 20 20 20 20 20 20 20 .+---------+...........|........
4840 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 .....+----------+...............
4860 20 20 20 76 20 20 20 20 20 20 20 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 20 20 20 ...v..............+---------+...
4880 20 20 20 20 20 20 20 20 76 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 7c 20 20 2b 2d ........v..................|..+-
48a0 2d 2d 2d 2d 2d 2d 2d 2d 2d 3e 7c 20 4d 6f 6e 69 74 6f 72 20 7c 3c 2d 2d 2d 2d 2d 2d 2d 2b 20 20 --------->|.Monitor.|<-------+..
48c0 7c 70 72 6f 6f 66 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 7c 20 20 7c 20 70 72 6f |proof..................|..|.pro
48e0 6f 66 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 20 20 20 64 61 74 61 20 7c 20 20 7c 6d 65 of.....+---------+...data.|..|me
4900 74 61 64 61 74 61 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 7c 20 20 7c 20 6d 65 74 tadata..................|..|.met
4920 61 64 61 74 61 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 7c 20 20 7c 64 61 adata.....................|..|da
4940 74 61 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 5e 20 20 7c 20 63 68 65 63 6b 73 75 ta..................^..|.checksu
4960 6d 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 7c 20 20 7c 00 20 20 2b 2d 2d m.....................|..|...+--
4980 2d 2d 2d 2b 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 20 20 20 20 20 20 20 20 20 20 ---+.......+---------+..........
49a0 20 20 20 20 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 00 20 20 7c 20 ...........+--------------+...|.
49c0 44 4e 53 20 7c 2d 2d 2d 2d 2d 2d 3e 7c 20 20 20 4c 6f 67 20 20 20 7c 2d 2d 2d 2d 2d 2d 2d 2d 2d DNS.|------>|...Log...|---------
49e0 2d 2b 20 20 20 20 20 20 20 20 20 20 7c 20 44 69 73 74 72 69 62 75 74 69 6f 6e 20 7c 00 20 20 2b -+..........|.Distribution.|...+
4a00 2d 2d 2d 2d 2d 2b 20 48 28 76 6b 29 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 20 20 20 70 72 6f 6f 66 -----+.H(vk).+---------+...proof
4a20 20 20 7c 20 20 20 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 00 20 20 ..|..........+--------------+...
4a40 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 76 20 20 20 20 20 20 20 20 20 20 20 20 20 ..................v.............
4a60 20 20 20 7c 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 76 00 20 20 20 20 20 20 20 20 20 20 ...|................v...........
4a80 20 20 20 20 20 20 20 20 20 20 7c 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 5e 20 20 20 20 ..........|................^....
4aa0 20 20 20 20 20 20 20 20 20 20 20 20 7c 20 70 72 6f 6f 66 00 20 20 20 20 20 20 20 20 20 20 20 6d ............|.proof............m
4ac0 65 74 61 64 61 74 61 20 7c 20 20 20 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 20 etadata.|..........+----------+.
4ae0 20 20 20 20 20 20 20 20 20 20 7c 20 6d 65 74 61 64 61 74 61 00 20 20 20 20 20 20 20 20 20 20 20 ..........|.metadata............
4b00 63 68 65 63 6b 73 75 6d 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 7c 20 20 53 69 67 6e 65 72 20 20 7c checksum.+----------|..Signer..|
4b20 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 20 64 61 74 61 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 -----------+.data...............
4b40 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 00 60 60 .................+----------+.``
4b60 60 00 77 65 20 67 69 76 65 20 61 20 62 72 69 65 66 20 70 72 69 6d 65 72 20 62 65 6c 6f 77 2e 00 `.we.give.a.brief.primer.below..
4b80 41 6e 20 6f 76 65 72 76 69 65 77 20 6f 66 20 73 69 67 73 75 6d 20 6c 6f 67 67 69 6e 67 20 69 73 An.overview.of.sigsum.logging.is
4ba0 20 73 68 6f 77 6e 20 69 6e 20 46 69 67 75 72 65 20 31 2e 20 20 42 65 66 6f 72 65 20 67 6f 69 6e .shown.in.Figure.1...Before.goin
4bc0 67 20 69 6e 74 6f 20 64 65 74 61 69 6c 00 23 23 20 33 20 2d 20 44 65 73 69 67 6e 00 00 61 74 74 g.into.detail.##.3.-.Design..att
4be0 61 63 6b 73 2e 20 20 20 41 20 6c 6f 67 20 6f 70 65 72 61 74 6f 72 20 63 61 6e 20 61 74 20 62 65 acks....A.log.operator.can.at.be
4c00 73 74 20 64 65 6e 79 20 73 65 72 76 69 63 65 20 77 69 74 68 20 74 68 65 73 65 20 61 73 73 75 6d st.deny.service.with.these.assum
4c20 70 74 69 6f 6e 73 2e 00 09 5b 73 6c 6f 77 2d 64 6f 77 6e 5d 28 68 74 74 70 73 3a 2f 2f 67 69 74 ptions...[slow-down](https://git
4c40 2e 73 69 67 73 75 6d 2e 6f 72 67 2f 73 69 67 73 75 6d 2f 74 72 65 65 2f 61 72 63 68 69 76 65 2f .sigsum.org/sigsum/tree/archive/
4c60 32 30 32 31 2d 30 38 2d 32 34 2d 63 68 65 63 6b 70 6f 69 6e 74 2d 74 69 6d 65 73 74 61 6d 70 29 2021-08-24-checkpoint-timestamp)
4c80 00 61 6e 64 00 09 5b 73 70 6c 69 74 2d 76 69 65 77 5d 28 68 74 74 70 73 3a 2f 2f 64 61 74 61 74 .and..[split-view](https://datat
4ca0 72 61 63 6b 65 72 2e 69 65 74 66 2e 6f 72 67 2f 64 6f 63 2f 68 74 6d 6c 2f 64 72 61 66 74 2d 69 racker.ietf.org/doc/html/draft-i
4cc0 65 74 66 2d 74 72 61 6e 73 2d 67 6f 73 73 69 70 2d 30 35 29 00 61 74 74 65 6d 70 74 73 00 77 69 etf-trans-gossip-05).attempts.wi
4ce0 74 6e 65 73 73 65 73 20 73 74 6f 70 20 66 6f 6c 6c 6f 77 69 6e 67 20 70 72 6f 74 6f 63 6f 6c 20 tnesses.stop.following.protocol.
4d00 74 6f 20 70 72 6f 74 65 63 74 20 61 67 61 69 6e 73 74 20 61 20 6d 61 6c 69 63 69 6f 75 73 20 6c to.protect.against.a.malicious.l
4d20 6f 67 20 74 68 61 74 00 73 69 67 6e 61 74 75 72 65 20 73 63 68 65 6d 65 2e 20 20 57 65 20 61 6c og.that.signature.scheme...We.al
4d40 73 6f 20 61 73 73 75 6d 65 20 74 68 61 74 20 61 74 20 6d 6f 73 74 20 61 20 74 68 72 65 73 68 6f so.assume.that.at.most.a.thresho
4d60 6c 64 20 6f 66 20 69 6e 64 65 70 65 6e 64 65 6e 74 00 46 6f 72 20 73 65 63 75 48 6f 77 48 6f 77 ld.of.independent.For.secuHowHow
4d80 65 76 65 72 2c 20 61 20 6c 6f 67 20 6f 70 65 72 61 74 6f 72 20 77 6f 75 6c 64 20 6f 6e 6c 79 20 ever,.a.log.operator.would.only.
4da0 64 6f 20 74 68 61 74 20 69 66 20 69 74 20 69 73 20 6c 69 6b 65 6c 79 20 74 6f 20 67 6f 20 75 6e do.that.if.it.is.likely.to.go.un
4dc0 6e 6f 74 69 63 65 64 2e 00 74 48 6f 77 65 76 65 72 2c 20 61 20 6c 6f 67 20 6f 70 65 72 61 74 6f noticed..tHowever,.a.log.operato
4de0 72 20 77 6f 75 6c 64 20 6f 6e 6c 79 20 64 6f 20 74 68 61 74 20 69 66 20 69 74 20 69 73 20 6c 69 r.would.only.do.that.if.it.is.li
4e00 6b 65 6c 79 20 74 6f 20 67 6f 20 75 6e 6e 6f 74 69 63 65 64 2e 00 74 68 65 20 73 61 6d 65 20 61 kely.to.go.unnoticed..the.same.a
4e20 70 70 65 6e 64 2d 6f 6e 6c 79 20 4d 65 72 6b 6c 65 20 74 72 65 65 20 74 6f 20 65 76 65 72 79 6f ppend-only.Merkle.tree.to.everyo
4e40 6e 65 20 62 65 63 61 75 73 65 20 69 74 20 69 73 20 61 74 74 61 63 6b 65 72 2d 63 6f 6e 74 72 6f ne.because.it.is.attacker-contro
4e60 6c 6c 65 64 2e 00 63 68 65 63 6b 73 75 6d 20 74 68 61 74 20 61 20 76 65 72 69 66 69 65 72 20 77 lled..checksum.that.a.verifier.w
4e80 6f 75 6c 64 20 61 63 63 65 70 74 2e 20 20 41 20 6c 6f 67 20 63 61 6e 20 6d 69 73 62 65 68 61 76 ould.accept...A.log.can.misbehav
4ea0 65 20 62 79 20 6e 6f 74 20 70 72 65 73 65 6e 74 69 6e 67 00 54 68 65 20 6f 76 65 72 61 6c 6c 20 e.by.not.presenting.The.overall.
4ec0 73 79 73 74 65 6d 20 69 73 20 73 61 69 64 20 74 6f 20 62 65 20 73 65 63 75 72 65 20 69 66 20 61 system.is.said.to.be.secure.if.a
4ee0 20 6d 6f 6e 69 74 6f 72 20 63 61 6e 20 64 69 73 63 6f 76 65 72 20 65 76 65 72 79 20 73 69 67 6e .monitor.can.discover.every.sign
4f00 65 64 00 00 09 5b 5c 5b 44 69 67 69 43 65 72 74 5c 5d 5d 28 68 74 74 70 73 3a 2f 2f 67 72 6f 75 ed...[\[DigiCert\]](https://grou
4f20 70 73 2e 67 6f 6f 67 6c 65 2e 63 6f 6d 2f 61 2f 63 68 72 6f 6d 69 75 6d 2e 6f 72 67 2f 67 2f 63 ps.google.com/a/chromium.org/g/c
4f40 74 2d 70 6f 6c 69 63 79 2f 63 2f 61 4b 4e 62 5a 75 4a 7a 77 66 4d 29 2e 00 54 72 61 6e 73 70 61 t-policy/c/aKNbZuJzwfM)..Transpa
4f60 72 65 6e 63 79 20 4c 6f 67 00 62 65 65 6e 20 74 68 65 20 63 61 73 65 20 77 68 65 6e 20 61 20 72 rency.Log.been.the.case.when.a.r
4f80 65 6d 6f 74 65 20 63 6f 64 65 20 65 78 65 63 75 74 69 6f 6e 20 77 61 73 20 66 6f 75 6e 64 20 66 emote.code.execution.was.found.f
4fa0 6f 72 20 61 20 43 65 72 74 69 66 69 63 61 74 65 00 64 69 73 74 72 69 62 75 74 65 20 69 74 20 74 or.a.Certificate.distribute.it.t
4fc0 6f 20 61 20 73 75 62 73 65 74 20 6f 66 20 69 73 6f 6c 61 74 65 64 20 76 65 72 69 66 69 65 72 73 o.a.subset.of.isolated.verifiers
4fe0 2e 20 20 46 6f 72 20 65 78 61 6d 70 6c 65 2c 20 74 68 69 73 20 63 6f 75 6c 64 20 68 61 76 65 00 ...For.example,.this.could.have.
5000 61 64 00 00 6f 02 00 00 7b 03 00 00 00 10 00 00 3c 00 00 00 00 00 00 00 ff 0f 00 00 b3 0f 00 00 ad..o...{.......<...............
5020 69 0f 00 00 1f 0f 00 00 16 0f 00 00 c6 0e 00 00 c2 0e 00 00 69 0e 00 00 1e 0e 00 00 1d 0e 00 00 i...................i...........
5040 0f 0e 00 00 c1 0d 00 00 a3 0d 00 00 9f 0d 00 00 73 0d 00 00 36 0d 00 00 f5 0c 00 00 b7 0c 00 00 ................s...6...........
5060 7f 0c 00 00 3e 0c 00 00 fd 0b 00 00 bc 0b 00 00 84 0b 00 00 48 0b 00 00 08 0b 00 00 cb 0a 00 00 ....>...............H...........
5080 93 0a 00 00 53 0a 00 00 13 0a 00 00 d3 09 00 00 ac 09 00 00 80 09 00 00 74 09 00 00 43 09 00 00 ....S...................t...C...
50a0 3f 09 00 00 3e 09 00 00 f2 08 00 00 a4 08 00 00 56 08 00 00 08 08 00 00 bc 07 00 00 bb 07 00 00 ?...>...........V...............
50c0 6a 07 00 00 1c 07 00 00 d1 06 00 00 85 06 00 00 84 06 00 00 3b 06 00 00 eb 05 00 00 9d 05 00 00 j...................;...........
50e0 4c 05 00 00 4b 05 00 00 fe 04 00 00 af 04 00 00 70 04 00 00 6f 04 00 00 59 04 00 00 09 04 00 00 L...K...........p...o...Y.......
5100 b9 03 00 00 7b 03 00 00 70 03 00 00 25 03 00 00 e3 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ....{...p...%...................
5120 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
5140 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
5160 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
5180 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
51a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
51c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
51e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
5200 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
5220 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
5240 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
5260 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
5280 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
52a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
52c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 64 69 73 64 69 73 74 72 69 62 75 .....................disdistribu
52e0 64 69 73 64 69 73 74 72 69 62 75 74 65 64 20 66 6f 72 6d 20 6f 66 20 74 72 75 73 74 2e 20 20 41 disdistributed.form.of.trust...A
5300 20 74 72 65 65 20 6c 65 61 66 20 63 6f 6e 74 61 69 6e 73 20 66 6f 75 72 20 66 69 65 6c 64 73 3a .tree.leaf.contains.four.fields:
5320 00 76 65 72 69 64 69 73 74 72 69 62 75 74 65 64 20 66 6f 72 6d 20 6f 66 20 74 72 75 73 74 2e 20 .veridistributed.form.of.trust..
5340 20 41 20 74 72 65 65 20 6c 65 61 66 20 63 6f 6e 74 61 69 6e 73 20 66 6f 75 72 20 66 69 65 6c 64 .A.tree.leaf.contains.four.field
5360 73 3a 00 76 65 72 69 66 79 20 74 68 61 74 20 74 64 69 73 74 72 69 62 75 74 65 64 64 69 73 74 72 s:.verify.that.tdistributeddistr
5380 69 62 75 74 65 64 20 66 6f 72 6d 20 6f 66 20 74 72 75 73 74 2e 20 20 41 20 74 72 65 65 20 6c 65 ibuted.form.of.trust...A.tree.le
53a0 61 66 20 63 6f 6e 74 61 69 6e 73 20 66 6f 75 72 20 66 69 65 6c 64 73 3a 00 76 65 72 69 66 79 20 af.contains.four.fields:.verify.
53c0 74 68 61 74 20 74 68 69 73 20 74 72 65 65 20 69 73 20 66 72 65 73 68 20 61 6e 64 20 61 70 70 65 that.this.tree.is.fresh.and.appe
53e0 6e 64 2d 6f 6e 6c 79 20 62 65 66 6f 72 65 20 63 6f 73 69 67 6e 69 6e 67 20 69 74 20 74 6f 20 61 nd-only.before.cosigning.it.to.a
5400 63 68 69 65 76 65 20 61 00 41 20 73 69 67 73 75 6d 20 6c 6f 67 20 6d 61 69 6e 74 61 69 6e 73 20 chieve.a.A.sigsum.log.maintains.
5420 61 20 70 75 62 6c 69 63 20 61 70 70 65 6e 64 2d 6f 6e 6c 79 20 4d 65 72 6b 6c 65 20 74 72 65 65 a.public.append-only.Merkle.tree
5440 2e 20 20 49 6e 64 65 70 65 6e 64 65 6e 74 20 77 69 74 6e 65 73 73 65 73 00 23 23 23 20 33 2e 31 ...Independent.witnesses.###.3.1
5460 20 2d 20 4d 65 72 6b 6c 65 20 74 72 65 65 00 00 63 6f 73 69 67 6e 69 6e 67 20 70 72 6f 74 6f 63 .-.Merkle.tree..cosigning.protoc
5480 6f 6c 2e 20 20 4d 6f 72 65 20 64 65 74 61 69 6c 20 69 73 20 70 72 6f 76 69 64 65 64 20 69 6e 20 ol...More.detail.is.provided.in.
54a0 53 65 63 74 69 6f 6e 20 33 2e 32 2e 33 2e 00 61 64 64 69 74 69 6f 6e 61 6c 20 6f 75 74 62 6f 75 Section.3.2.3..additional.outbou
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54e0 73 68 6f 6c 64 20 6f 66 20 77 69 74 6e 65 73 73 65 73 20 66 6f 6c 6c 6f 77 65 64 20 61 00 56 65 shold.of.witnesses.followed.a.Ve
5500 72 69 66 69 65 72 73 20 61 6e 64 20 6d 6f 6e 69 74 6f 72 73 20 63 61 6e 20 62 65 20 63 6f 6e 76 rifiers.and.monitors.can.be.conv
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5540 65 64 20 77 69 74 68 6f 75 74 00 00 74 68 65 69 72 20 6b 65 79 2d 75 73 61 67 65 20 63 61 6e 20 ed.without..their.key-usage.can.
5560 6e 6f 77 20 62 65 20 76 65 72 69 66 69 65 64 20 62 65 63 61 75 73 65 20 6e 6f 20 73 69 67 6e 69 now.be.verified.because.no.signi
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55a0 73 20 74 68 61 74 20 74 68 65 79 20 61 72 65 20 61 77 61 72 65 20 6f 66 2e 20 20 41 6e 79 20 66 s.that.they.are.aware.of...Any.f
55c0 61 6c 73 69 66 69 61 62 6c 65 20 63 6c 61 69 6d 20 74 68 61 74 20 61 20 73 69 67 6e 65 72 20 6d alsifiable.claim.that.a.signer.m
55e0 61 6b 65 73 20 61 62 6f 75 74 00 6c 6f 67 67 69 6e 67 2e 20 20 4d 6f 6e 69 74 6f 72 73 20 6c 6f akes.about.logging...Monitors.lo
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5660 20 69 73 20 61 63 63 6f 6d 70 61 6e 69 65 64 20 62 79 20 70 72 6f 6f 66 73 20 6f 66 20 70 75 62 .is.accompanied.by.proofs.of.pub
5680 6c 69 63 00 00 6c 6f 67 67 69 6e 67 2e 20 20 41 20 73 69 67 73 75 6d 20 6c 6f 67 20 64 6f 65 73 lic..logging...A.sigsum.log.does
56a0 20 6e 6f 74 20 68 65 6c 70 20 74 68 65 20 73 69 67 6e 65 72 20 77 69 74 68 20 61 6e 79 20 64 61 .not.help.the.signer.with.any.da
56c0 74 61 20 64 69 73 74 72 69 62 75 74 69 6f 6e 2e 00 74 68 65 20 73 69 67 6e 65 64 20 63 68 65 63 ta.distribution..the.signed.chec
56e0 6b 73 75 6d 27 73 20 64 61 74 61 20 69 73 20 72 65 61 64 79 20 66 6f 72 20 64 69 73 74 72 69 62 ksum's.data.is.ready.for.distrib
5700 75 74 69 6f 6e 20 77 69 74 68 20 70 72 6f 6f 66 73 20 6f 66 20 70 75 62 6c 69 63 00 69 6e 63 6c ution.with.proofs.of.public.incl
5720 75 73 69 6f 6e 20 70 72 6f 6f 66 20 69 73 20 61 76 61 69 6c 61 62 6c 65 20 74 68 61 74 20 6c 65 usion.proof.is.available.that.le
5740 61 64 73 20 75 70 20 74 6f 20 61 20 74 72 75 73 74 77 6f 72 74 68 79 20 4d 65 72 6b 6c 65 20 74 ads.up.to.a.trustworthy.Merkle.t
5760 72 65 65 20 68 65 61 64 2c 00 54 68 65 20 73 69 67 6e 69 6e 67 20 70 61 72 74 79 20 77 61 69 74 ree.head,.The.signing.party.wait
5780 73 20 66 6f 72 20 74 68 65 69 72 20 73 75 62 6d 69 73 73 69 6f 6e 20 74 6f 20 62 65 20 69 6e 63 s.for.their.submission.to.be.inc
57a0 6c 75 64 65 64 20 69 6e 20 74 68 65 20 6c 6f 67 2e 20 20 57 68 65 6e 20 61 6e 00 00 6b 65 79 20 luded.in.the.log...When.an..key.
57c0 69 73 20 63 6f 6e 66 69 67 75 72 65 64 20 69 6e 20 44 4e 53 20 61 73 20 61 20 54 58 54 20 72 65 is.configured.in.DNS.as.a.TXT.re
57e0 63 6f 72 64 20 74 6f 20 68 65 6c 70 20 6c 6f 67 20 6f 70 65 72 61 74 6f 72 73 20 63 6f 6d 62 61 cord.to.help.log.operators.comba
5800 74 20 73 70 61 6d 2e 00 61 6e 64 20 61 20 68 61 73 68 20 6f 66 20 74 68 65 20 70 75 62 6c 69 63 t.spam..and.a.hash.of.the.public
5820 20 76 65 72 69 66 69 63 61 74 69 6f 6e 20 6b 65 79 2e 20 20 41 20 68 61 73 68 20 6f 66 20 74 68 .verification.key...A.hash.of.th
5840 65 20 70 75 62 6c 69 63 20 76 65 72 69 66 69 63 61 74 69 6f 6e 00 64 61 74 61 2e 20 20 4d 69 6e e.public.verification.data...Min
5860 69 6d 61 6c 20 6d 65 74 61 64 61 74 61 20 6d 75 73 74 20 61 6c 73 6f 20 62 65 20 6c 6f 67 67 65 imal.metadata.must.also.be.logge
5880 64 2c 20 73 75 63 68 20 61 73 20 74 68 65 20 63 68 65 63 6b 73 75 6d 27 73 20 73 69 67 6e 61 74 d,.such.as.the.checksum's.signat
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58c0 63 63 65 70 74 2e 20 20 54 68 61 74 20 73 74 61 74 65 6d 65 6e 74 20 65 6e 63 6f 64 65 73 20 61 ccept...That.statement.encodes.a
58e0 20 63 68 65 63 6b 73 75 6d 20 6f 66 20 73 6f 6d 65 00 41 20 73 69 67 6e 65 72 20 77 61 6e 74 73 .checksum.of.some.A.signer.wants
5900 20 74 6f 20 6d 61 6b 65 20 74 68 65 69 72 20 6b 65 79 2d 75 73 61 67 65 20 74 72 61 6e 73 70 61 .to.make.their.key-usage.transpa
5920 72 65 6e 74 2e 20 20 54 68 65 72 65 66 6f 72 65 2c 20 74 68 65 79 20 73 69 67 6e 20 61 00 00 60 rent...Therefore,.they.sign.a..`
5940 60 60 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 46 69 67 75 72 65 ``........................Figure
5960 20 31 3a 20 73 79 73 74 65 6d 20 6f 76 65 72 76 69 65 77 00 20 20 20 20 20 20 20 20 20 20 20 00 .1:.system.overview.............
5980 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 ................................
59a0 69 6e 76 65 73 74 69 67 61 74 65 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 investigate.....................
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59e0 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 20 20 20 20 20 20 20 20 20 20 20 7c 20 63 6c 61 69 6d 20 ..+---------+...........|.claim.
5a00 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 00 20 20 20 20 20 20 20 20 20 20 20 20 20 ......+----------+..............
5a20 20 20 7c 20 77 69 74 6e 65 73 73 20 7c 20 20 20 20 20 20 20 20 20 20 20 7c 20 66 61 6c 73 65 20 ..|.witness.|...........|.false.
5a40 20 20 20 20 20 20 7c 20 56 65 72 69 66 69 65 72 20 7c 00 20 20 20 20 20 20 20 20 20 20 20 20 20 ......|.Verifier.|..............
5a60 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 20 20 20 20 20 20 20 20 20 20 20 7c 20 20 20 20 20 20 20 ..+---------+...........|.......
5a80 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 00 20 20 20 20 20 20 20 20 20 20 20 20 20 ......+----------+..............
5aa0 20 20 20 20 76 20 20 20 20 20 20 20 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 20 20 ....v..............+---------+..
5ac0 20 20 20 20 20 20 20 20 20 76 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 7c 20 20 2b .........v..................|..+
5ae0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 3e 7c 20 4d 6f 6e 69 74 6f 72 20 7c 3c 2d 2d 2d 2d 2d 2d 2d 2b 20 ---------->|.Monitor.|<-------+.
5b00 20 7c 70 72 6f 6f 66 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 7c 20 20 7c 20 70 72 .|proof..................|..|.pr
5b20 6f 6f 66 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 20 20 20 64 61 74 61 20 7c 20 20 7c 6d oof.....+---------+...data.|..|m
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5b60 74 61 64 61 74 61 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 7c 20 20 7c 64 tadata.....................|..|d
5b80 61 74 61 00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 5e 20 20 7c 20 63 68 65 63 6b 73 ata..................^..|.checks
5ba0 75 6d 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 7c 20 20 7c 00 20 20 2b 2d um.....................|..|...+-
5bc0 2d 2d 2d 2d 2b 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 20 20 20 20 20 20 20 20 20 ----+.......+---------+.........
5be0 20 20 20 20 20 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 00 20 20 7c ............+--------------+...|
5c00 20 44 4e 53 20 7c 2d 2d 2d 2d 2d 2d 3e 7c 20 20 20 4c 6f 67 20 20 20 7c 2d 2d 2d 2d 2d 2d 2d 2d .DNS.|------>|...Log...|--------
5c20 2d 2d 2b 20 20 20 20 20 20 20 20 20 20 7c 20 44 69 73 74 72 69 62 75 74 69 6f 6e 20 7c 00 20 20 --+..........|.Distribution.|...
5c40 2b 2d 2d 2d 2d 2d 2b 20 48 28 76 6b 29 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 20 20 20 70 72 6f 6f +-----+.H(vk).+---------+...proo
5c60 66 20 20 7c 20 20 20 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 00 20 f..|..........+--------------+..
5c80 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 76 20 20 20 20 20 20 20 20 20 20 20 20 ...................v............
5ca0 20 20 20 20 7c 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 76 00 20 20 20 20 20 20 20 20 20 ....|................v..........
5cc0 20 20 20 20 20 20 20 20 20 20 20 7c 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 5e 20 20 20 ...........|................^...
5ce0 20 20 20 20 20 20 20 20 20 20 20 20 20 7c 20 70 72 6f 6f 66 00 20 20 20 20 20 20 20 20 20 20 20 .............|.proof............
5d00 6d 65 74 61 64 61 74 61 20 7c 20 20 20 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b metadata.|..........+----------+
5d20 20 20 20 20 20 20 20 20 20 20 20 7c 20 6d 65 74 61 64 61 74 61 00 20 20 20 20 20 20 20 20 20 20 ...........|.metadata...........
5d40 20 63 68 65 63 6b 73 75 6d 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 7c 20 20 53 69 67 6e 65 72 20 20 .checksum.+----------|..Signer..
5d60 7c 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 20 64 61 74 61 00 20 20 20 20 20 20 20 20 20 20 20 20 20 |-----------+.data..............
5d80 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 00 60 ..................+----------+.`
5da0 60 60 00 77 65 20 67 69 76 65 20 61 20 62 72 69 65 66 20 70 72 69 6d 65 72 20 62 65 6c 6f 77 2e ``.we.give.a.brief.primer.below.
5dc0 00 41 6e 20 6f 76 65 72 76 69 65 77 20 6f 66 20 73 69 67 73 75 6d 20 6c 6f 67 67 69 6e 67 20 69 .An.overview.of.sigsum.logging.i
5de0 73 20 73 68 6f 77 6e 20 69 6e 20 46 69 67 75 72 65 20 31 2e 20 20 42 65 66 6f 72 65 20 67 6f 69 s.shown.in.Figure.1...Before.goi
5e00 6e 67 20 69 6e 74 6f 20 64 65 74 61 69 6c 00 23 23 20 33 20 2d 20 44 65 73 69 67 6e 00 00 61 74 ng.into.detail.##.3.-.Design..at
5e20 74 61 63 6b 73 2e 20 20 20 41 20 6c 6f 67 20 6f 70 65 72 61 74 6f 72 20 63 61 6e 20 61 74 20 62 tacks....A.log.operator.can.at.b
5e40 65 73 74 20 64 65 6e 79 20 73 65 72 76 69 63 65 20 77 69 74 68 20 74 68 65 73 65 20 61 73 73 75 est.deny.service.with.these.assu
5e60 6d 70 74 69 6f 6e 73 2e 00 09 5b 73 6c 6f 77 2d 64 6f 77 6e 5d 28 68 74 74 70 73 3a 2f 2f 67 69 mptions...[slow-down](https://gi
5e80 74 2e 73 69 67 73 75 6d 2e 6f 72 67 2f 73 69 67 73 75 6d 2f 74 72 65 65 2f 61 72 63 68 69 76 65 t.sigsum.org/sigsum/tree/archive
5ea0 2f 32 30 32 31 2d 30 38 2d 32 34 2d 63 68 65 63 6b 70 6f 69 6e 74 2d 74 69 6d 65 73 74 61 6d 70 /2021-08-24-checkpoint-timestamp
5ec0 29 00 61 6e 64 00 09 5b 73 70 6c 69 74 2d 76 69 65 77 5d 28 68 74 74 70 73 3a 2f 2f 64 61 74 61 ).and..[split-view](https://data
5ee0 74 72 61 63 6b 65 72 2e 69 65 74 66 2e 6f 72 67 2f 64 6f 63 2f 68 74 6d 6c 2f 64 72 61 66 74 2d tracker.ietf.org/doc/html/draft-
5f00 69 65 74 66 2d 74 72 61 6e 73 2d 67 6f 73 73 69 70 2d 30 35 29 00 61 74 74 65 6d 70 74 73 00 77 ietf-trans-gossip-05).attempts.w
5f20 69 74 6e 65 73 73 65 73 20 73 74 6f 70 20 66 6f 6c 6c 6f 77 69 6e 67 20 70 72 6f 74 6f 63 6f 6c itnesses.stop.following.protocol
5f40 20 74 6f 20 70 72 6f 74 65 63 74 20 61 67 61 69 6e 73 74 20 61 20 6d 61 6c 69 63 69 6f 75 73 20 .to.protect.against.a.malicious.
5f60 6c 6f 67 20 74 68 61 74 00 73 69 67 6e 61 74 75 72 65 20 73 63 68 65 6d 65 2e 20 20 57 65 20 61 log.that.signature.scheme...We.a
5f80 6c 73 6f 20 61 73 73 75 6d 65 20 74 68 61 74 20 61 74 20 6d 6f 73 74 20 61 20 74 68 72 65 73 68 lso.assume.that.at.most.a.thresh
5fa0 6f 6c 64 20 6f 66 20 69 6e 64 65 70 65 6e 64 65 6e 74 00 46 6f 72 20 73 65 63 75 72 69 74 79 20 old.of.independent.For.security.
5fc0 77 65 20 6e 65 65 64 20 61 20 63 6f 6c 6c 69 73 69 6f 6e 20 72 65 73 69 73 74 61 6e 74 20 68 61 we.need.a.collision.resistant.ha
5fe0 73 68 20 66 75 6e 63 74 69 6f 6e 20 61 6e 64 20 61 6e 20 75 6e 66 6f 72 67 65 61 62 6c 65 00 00 sh.function.and.an.unforgeable..
6000 61 64 00 00 1a 00 00 00 1a 01 00 00 00 10 00 00 39 00 00 00 00 00 00 00 ff 0f 00 00 b0 0f 00 00 ad..............9...............
6020 62 0f 00 00 21 0f 00 00 da 0e 00 00 8f 0e 00 00 8e 0e 00 00 75 0e 00 00 25 0e 00 00 de 0d 00 00 b...!...............u...%.......
6040 90 0d 00 00 40 0d 00 00 ef 0c 00 00 9f 0c 00 00 4c 0c 00 00 fe 0b 00 00 ae 0b 00 00 5e 0b 00 00 ....@...........L...........^...
6060 10 0b 00 00 c4 0a 00 00 7b 0a 00 00 2b 0a 00 00 db 09 00 00 8e 09 00 00 3f 09 00 00 f1 08 00 00 ........{...+...........?.......
6080 a5 08 00 00 71 08 00 00 1d 08 00 00 cf 07 00 00 81 07 00 00 4d 07 00 00 03 07 00 00 bd 06 00 00 ....q...............M...........
60a0 6f 06 00 00 18 06 00 00 cb 05 00 00 81 05 00 00 31 05 00 00 f3 04 00 00 f2 04 00 00 e0 04 00 00 o...............1...............
60c0 91 04 00 00 46 04 00 00 45 04 00 00 31 04 00 00 e3 03 00 00 94 03 00 00 47 03 00 00 f6 02 00 00 ....F...E...1...........G.......
60e0 a0 02 00 00 5b 02 00 00 28 02 00 00 b3 01 00 00 b2 01 00 00 62 01 00 00 1a 01 00 00 19 01 00 00 ....[...(...........b...........
6100 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 54 68 69 73 20 63 ..........................This.c
6120 6f 76 65 72 73 20 61 20 77 65 61 6b 65 72 20 66 6f 72 6d 20 6f 66 20 61 74 74 61 63 6b 65 72 20 overs.a.weaker.form.of.attacker.
6140 74 68 61 74 20 69 73 20 61 62 6c 65 20 74 6f 20 73 69 67 6e 20 6c 6f 67 20 64 61 74 61 20 61 6e that.is.able.to.sign.log.data.an
6160 64 00 54 68 65 20 61 74 74 61 63 6b 65 72 20 63 61 6e 20 61 6c 73 6f 20 67 61 69 6e 20 63 6f 6e d.The.attacker.can.also.gain.con
6180 74 72 6f 6c 20 6f 66 20 74 68 65 20 6c 6f 67 27 73 20 73 69 67 6e 69 6e 67 20 6b 65 79 20 61 6e trol.of.the.log's.signing.key.an
61a0 64 20 69 6e 66 72 61 73 74 72 75 63 74 75 72 65 2e 00 00 09 5b 5c 5b 53 6f 6c 61 72 57 69 6e 64 d.infrastructure....[\[SolarWind
61c0 73 5c 5d 5d 28 68 74 74 70 73 3a 2f 2f 77 77 77 2e 7a 64 6e 65 74 2e 63 6f 6d 2f 61 72 74 69 63 s\]](https://www.zdnet.com/artic
61e0 6c 65 2f 74 68 69 72 64 2d 6d 61 6c 77 61 72 65 2d 73 74 72 61 69 6e 2d 64 69 73 63 6f 76 65 72 le/third-malware-strain-discover
6200 65 64 2d 69 6e 2d 73 6f 6c 61 72 77 69 6e 64 73 2d 73 75 70 70 6c 79 2d 63 68 61 69 6e 2d 61 74 ed-in-solarwinds-supply-chain-at
6220 74 61 63 6b 2f 29 2e 00 63 6f 6d 70 72 6f 6d 69 73 65 64 20 73 68 6f 75 6c 64 20 6e 6f 74 20 62 tack/)..compromised.should.not.b
6240 65 20 63 6f 6e 74 72 6f 76 65 72 73 69 61 6c 20 74 68 65 73 65 20 64 61 79 73 00 54 68 65 20 66 e.controversial.these.days.The.f
6260 61 63 74 20 74 68 61 74 20 73 69 67 6e 69 6e 67 20 6b 65 79 73 20 61 6e 64 20 72 65 6c 61 74 65 act.that.signing.keys.and.relate
6280 64 20 69 6e 66 72 61 73 74 72 75 63 74 75 72 65 20 63 6f 6d 70 6f 6e 65 6e 74 73 20 67 65 74 00 d.infrastructure.components.get.
62a0 09 5b 5c 5b 46 42 49 2d 41 70 70 6c 65 5c 5d 5d 28 68 74 74 70 73 3a 2f 2f 77 77 77 2e 65 66 66 .[\[FBI-Apple\]](https://www.eff
62c0 2e 6f 72 67 2f 63 61 73 65 73 2f 61 70 70 6c 65 2d 63 68 61 6c 6c 65 6e 67 65 73 2d 66 62 69 2d .org/cases/apple-challenges-fbi-
62e0 61 6c 6c 2d 77 72 69 74 73 2d 61 63 74 2d 6f 72 64 65 72 29 2e 00 74 68 69 73 20 69 73 20 65 73 all-writs-act-order)..this.is.es
6300 73 65 6e 74 69 61 6c 6c 79 20 77 68 61 74 20 74 68 65 20 46 42 49 20 72 65 71 75 65 73 74 65 64 sentially.what.the.FBI.requested
6320 20 66 72 6f 6d 20 41 70 70 6c 65 20 69 6e 20 74 68 65 20 53 61 6e 20 42 65 72 6e 61 72 64 69 6e .from.Apple.in.the.San.Bernardin
6340 6f 20 63 61 73 65 00 73 69 67 6e 20 64 61 74 61 20 61 6e 64 20 64 69 73 74 72 69 62 75 74 65 20 o.case.sign.data.and.distribute.
6360 69 74 20 74 6f 20 61 20 73 75 62 73 65 74 20 6f 66 20 69 73 6f 6c 61 74 65 64 20 76 65 72 69 66 it.to.a.subset.of.isolated.verif
6380 69 65 72 73 2e 20 20 46 6f 72 20 65 78 61 6d 70 6c 65 2c 00 72 65 6c 65 61 73 65 20 69 6e 66 72 iers...For.example,.release.infr
63a0 61 73 74 72 75 63 74 75 72 65 2e 20 20 54 68 69 73 20 63 6f 76 65 72 73 20 61 20 77 65 61 6b 65 astructure...This.covers.a.weake
63c0 72 20 66 6f 72 6d 20 6f 66 20 61 74 74 61 63 6b 65 72 20 74 68 61 74 20 69 73 20 61 62 6c 65 20 r.form.of.attacker.that.is.able.
63e0 74 6f 00 57 65 20 63 6f 6e 73 69 64 65 72 20 61 20 70 6f 77 65 72 66 75 6c 20 61 74 74 61 63 6b to.We.consider.a.powerful.attack
6400 65 72 20 74 68 61 74 20 67 61 69 6e 65 64 20 63 6f 6e 74 72 6f 6c 20 6f 66 20 61 20 73 69 67 6e er.that.gained.control.of.a.sign
6420 65 72 27 73 20 73 69 67 6e 69 6e 67 20 61 6e 64 00 23 23 20 32 20 2d 20 54 68 72 65 61 74 20 6d er's.signing.and.##.2.-.Threat.m
6440 6f 64 65 6c 00 00 46 69 6e 61 6c 6c 79 2c 20 77 65 20 77 72 61 70 20 75 70 20 77 69 74 68 20 61 odel..Finally,.we.wrap.up.with.a
6460 6e 20 69 6e 63 6f 6d 70 6c 65 74 65 20 66 72 65 71 75 65 6e 74 6c 79 20 61 73 6b 65 64 20 71 75 n.incomplete.frequently.asked.qu
6480 65 73 74 69 6f 6e 73 20 73 65 63 74 69 6f 6e 2e 00 46 69 72 73 74 20 77 65 20 64 65 73 63 72 69 estions.section..First.we.descri
64a0 62 65 20 6f 75 72 20 74 68 72 65 61 74 20 6d 6f 64 65 6c 2e 20 20 54 68 65 6e 20 77 65 20 67 69 be.our.threat.model...Then.we.gi
64c0 76 65 20 61 20 62 69 72 64 27 73 20 76 69 65 77 20 6f 66 20 74 68 65 20 64 65 73 69 67 6e 2e 00 ve.a.bird's.view.of.the.design..
64e0 23 23 23 20 31 2e 33 20 2d 20 52 6f 61 64 6d 61 70 00 00 20 20 20 20 20 20 20 20 5b 41 50 49 5d ###.1.3.-.Roadmap..........[API]
6500 28 68 74 74 70 73 3a 2f 2f 67 69 74 2e 73 69 67 73 75 6d 2e 6f 72 67 2f 73 69 67 73 75 6d 2f 74 (https://git.sigsum.org/sigsum/t
6520 72 65 65 2f 64 6f 63 2f 61 70 69 2e 6d 64 29 2e 00 61 64 64 69 74 69 6f 6e 61 6c 6c 79 20 6e 65 ree/doc/api.md)..additionally.ne
6540 65 64 20 74 6f 20 69 6e 74 65 72 61 63 74 20 77 69 74 68 20 61 20 73 69 67 73 75 6d 20 6c 6f 67 ed.to.interact.with.a.sigsum.log
6560 27 73 20 6c 69 6e 65 2d 74 65 72 6d 69 6e 61 74 65 64 20 41 53 43 49 49 20 48 54 54 50 28 53 29 's.line-terminated.ASCII.HTTP(S)
6580 00 74 68 61 74 20 61 20 76 65 72 69 66 69 65 72 20 69 73 20 72 65 71 75 69 72 65 64 20 74 6f 20 .that.a.verifier.is.required.to.
65a0 73 75 70 70 6f 72 74 2e 20 20 53 69 67 6e 65 72 73 2c 20 6d 6f 6e 69 74 6f 72 73 2c 20 61 6e 64 support...Signers,.monitors,.and
65c0 20 77 69 74 6e 65 73 73 65 73 00 6f 72 20 22 62 79 20 68 61 6e 64 22 20 69 6e 20 6d 61 6e 79 20 .witnesses.or."by.hand".in.many.
65e0 6d 6f 64 65 72 6e 20 70 72 6f 67 72 61 6d 6d 69 6e 67 20 6c 61 6e 67 75 61 67 65 73 2e 20 20 54 modern.programming.languages...T
6600 68 69 73 20 69 73 20 74 68 65 20 6f 6e 6c 79 20 70 61 72 73 69 6e 67 00 09 5b 54 72 75 6e 6e 65 his.is.the.only.parsing..[Trunne
6620 6c 5d 28 68 74 74 70 73 3a 2f 2f 67 69 74 6c 61 62 2e 74 6f 72 70 72 6f 6a 65 63 74 2e 6f 72 67 l](https://gitlab.torproject.org
6640 2f 74 70 6f 2f 63 6f 72 65 2f 74 72 75 6e 6e 65 6c 2f 2d 2f 62 6c 6f 62 2f 6d 61 69 6e 2f 64 6f /tpo/core/trunnel/-/blob/main/do
6660 63 2f 74 72 75 6e 6e 65 6c 2e 6d 64 29 2c 00 63 6f 6e 73 74 72 61 69 6e 65 64 20 65 6e 76 69 72 c/trunnel.md),.constrained.envir
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6700 69 6e 00 2d 20 2a 2a 53 69 6d 70 6c 65 20 28 64 65 29 73 65 72 69 61 6c 69 7a 61 74 69 6f 6e 20 in.-.**Simple.(de)serialization.
6720 70 61 72 73 65 72 73 3a 2a 2a 20 63 6f 6d 70 6c 65 78 20 28 64 65 29 73 65 72 69 61 6c 69 7a 61 parsers:**.complex.(de)serializa
6740 74 69 6f 6e 20 70 61 72 73 65 72 73 00 70 72 6f 74 6f 63 6f 6c 73 20 61 6e 64 20 64 61 74 61 20 tion.parsers.protocols.and.data.
6760 66 6f 72 6d 61 74 73 20 73 69 6d 70 6c 65 72 20 61 6e 64 20 6d 6f 72 65 20 73 65 63 75 72 65 2e formats.simpler.and.more.secure.
6780 00 66 75 6e 63 74 69 6f 6e 73 20 61 72 65 20 45 64 32 35 35 31 39 20 61 6e 64 20 53 48 41 32 35 .functions.are.Ed25519.and.SHA25
67a0 36 2e 20 20 4e 6f 74 20 68 61 76 69 6e 67 20 61 6e 79 20 63 72 79 70 74 6f 67 72 61 70 68 69 63 6...Not.having.any.cryptographic
67c0 20 61 67 69 6c 69 74 79 20 6d 61 6b 65 73 00 2d 20 2a 2a 4e 6f 20 63 72 79 70 74 6f 67 72 61 70 .agility.makes.-.**No.cryptograp
67e0 68 69 63 20 61 67 69 6c 69 74 79 2a 2a 3a 20 74 68 65 20 6f 6e 6c 79 20 73 75 70 70 6f 72 74 65 hic.agility**:.the.only.supporte
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6840 6c 6f 72 65 2e 69 65 65 65 2e 6f 72 67 2f 73 74 61 6d 70 2f 73 74 61 6d 70 2e 6a 73 70 3f 61 72 lore.ieee.org/stamp/stamp.jsp?ar
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68a0 74 20 6f 66 00 6c 6f 67 73 20 72 65 6c 79 20 6f 6e 20 67 6f 73 73 69 70 20 70 72 6f 74 6f 63 6f t.of.logs.rely.on.gossip.protoco
68c0 6c 73 20 74 6f 20 64 65 74 65 63 74 20 66 6f 72 6b 73 2e 20 20 57 65 20 62 75 69 6c 74 20 61 20 ls.to.detect.forks...We.built.a.
68e0 70 72 6f 61 63 74 69 76 65 20 67 6f 73 73 69 70 00 2d 20 2a 2a 42 75 69 6c 74 2d 69 6e 20 6d 65 proactive.gossip.-.**Built-in.me
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6920 63 6f 6e 73 69 73 74 65 6e 74 20 6c 6f 67 3a 2a 2a 20 74 72 61 6e 73 70 61 72 65 6e 63 79 00 63 consistent.log:**.transparency.c
6940 6f 6d 62 61 74 20 6c 6f 67 20 73 70 61 6d 2e 20 20 53 68 61 72 64 69 6e 67 20 69 73 20 61 6c 73 ombat.log.spam...Sharding.is.als
6960 6f 20 68 65 6c 70 66 75 6c 20 74 6f 20 63 6f 6d 62 61 74 20 6c 6f 67 20 73 70 61 6d 20 69 6e 20 o.helpful.to.combat.log.spam.in.
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6a00 61 64 20 74 6f 20 61 62 75 73 69 76 65 20 75 73 61 67 65 20 70 61 74 74 65 72 6e 73 2e 20 20 57 ad.to.abusive.usage.patterns...W
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6a40 62 65 20 6f 70 65 6e 20 66 6f 72 20 65 76 65 72 79 6f 6e 65 2e 20 20 48 6f 77 65 76 65 72 2c 20 be.open.for.everyone...However,.
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6aa0 73 6f 6e 69 6e 67 3a 2a 2a 20 74 6f 20 6b 65 65 70 20 6c 6f 67 73 20 61 73 20 75 73 65 66 75 6c soning:**.to.keep.logs.as.useful
6ac0 20 61 73 00 61 6e 20 6f 6c 64 65 72 20 6c 6f 67 20 73 68 61 72 64 20 63 61 6e 6e 6f 74 20 62 65 .as.an.older.log.shard.cannot.be
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6b00 70 69 6e 67 20 6c 6f 67 20 73 68 61 72 64 2e 00 74 68 61 74 20 64 65 74 65 72 6d 69 6e 65 73 20 ping.log.shard..that.determines.
6b20 74 68 65 20 74 69 6d 65 20 64 75 72 69 6e 67 20 77 68 69 63 68 20 74 68 65 20 6c 6f 67 20 77 69 the.time.during.which.the.log.wi
6b40 6c 6c 20 62 65 20 61 63 74 69 76 65 2e 20 20 53 75 62 6d 69 73 73 69 6f 6e 73 20 74 6f 00 74 68 ll.be.active...Submissions.to.th
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6b80 20 77 61 79 2e 20 20 57 65 20 68 61 76 65 20 61 20 70 72 65 64 65 66 69 6e 65 64 20 73 68 61 72 .way...We.have.a.predefined.shar
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6c00 20 6f 74 68 65 72 20 77 6f 72 64 73 2c 20 74 68 65 20 73 69 67 6e 65 72 20 74 61 6c 6b 73 20 74 .other.words,.the.signer.talks.t
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6c80 20 64 69 73 74 72 69 62 75 74 69 6e 67 20 74 68 65 20 61 63 74 75 61 6c 20 64 61 74 61 2e 00 61 .distributing.the.actual.data..a
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6d00 61 20 66 6c 6f 77 73 3a 2a 2a 20 61 20 76 65 72 69 66 69 65 72 20 63 61 6e 20 65 6e 66 6f 72 63 a.flows:**.a.verifier.can.enforc
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6d40 62 75 74 20 69 74 20 69 73 20 6d 61 74 75 72 65 20 65 6e 6f 75 67 68 20 74 6f 20 63 61 70 74 75 but.it.is.mature.enough.to.captu
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6d80 74 20 74 6f 20 62 6f 6f 74 73 74 72 61 70 2e 00 70 72 6f 70 65 72 74 69 65 73 2e 20 20 49 74 20 t.to.bootstrap..properties...It.
6da0 64 6f 65 73 20 6e 6f 74 20 6d 65 61 6e 20 74 68 61 74 20 74 68 65 20 73 69 67 73 75 6d 20 6c 6f does.not.mean.that.the.sigsum.lo
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6de0 20 73 69 67 73 75 6d 20 6c 6f 67 73 2c 20 75 6c 74 69 6d 61 74 65 6c 79 20 6c 65 61 76 69 6e 67 .sigsum.logs,.ultimately.leaving
6e00 20 75 73 20 77 69 74 68 20 61 20 64 65 73 69 67 6e 20 74 68 61 74 20 68 61 73 20 74 68 65 20 62 .us.with.a.design.that.has.the.b
6e20 65 6c 6f 77 00 49 74 20 69 73 20 66 61 69 72 20 74 6f 20 73 61 79 20 74 68 61 74 20 6d 75 63 68 elow.It.is.fair.to.say.that.much
6e40 20 74 68 6f 75 67 68 20 77 65 6e 74 20 69 6e 74 6f 20 5f 72 65 6d 6f 76 69 6e 67 5f 20 75 6e 77 .though.went.into._removing_.unw
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6e80 6f 67 20 70 72 6f 70 65 72 74 69 65 73 00 00 09 5b 47 32 5c 5d 5d 28 68 74 74 70 73 3a 2f 2f 64 og.properties...[G2\]](https://d
6ea0 61 74 61 74 72 61 63 6b 65 72 2e 69 65 74 66 2e 6f 72 67 2f 64 6f 63 2f 68 74 6d 6c 2f 64 72 61 atatracker.ietf.org/doc/html/dra
6ec0 66 74 2d 69 65 74 66 2d 74 72 61 6e 73 2d 67 6f 73 73 69 70 2d 30 35 29 2e 00 09 5b 5c 5b 47 31 ft-ietf-trans-gossip-05)...[\[G1
6ee0 2c 5d 28 68 74 74 70 73 3a 2f 2f 69 65 65 65 78 70 6c 6f 72 65 2e 69 65 65 65 2e 6f 72 67 2f 73 ,](https://ieeexplore.ieee.org/s
6f00 74 61 6d 70 2f 73 74 61 6d 70 2e 6a 73 70 3f 61 72 6e 75 6d 62 65 72 3d 37 33 34 36 38 35 33 29 tamp/stamp.jsp?arnumber=7346853)
6f20 00 70 72 6f 6d 69 73 65 73 2c 20 61 6e 64 20 64 65 70 6c 6f 79 6d 65 6e 74 20 6f 66 20 61 20 67 .promises,.and.deployment.of.a.g
6f40 6f 73 73 69 70 20 70 72 6f 74 6f 63 6f 6c 20 74 68 61 74 20 73 75 69 74 73 20 74 68 65 20 77 65 ossip.protocol.that.suits.the.we
6f60 62 00 73 74 6f 72 61 67 65 20 6f 66 20 61 72 62 69 74 72 61 72 79 20 63 65 72 74 69 66 69 63 61 b.storage.of.arbitrary.certifica
6f80 74 65 20 66 69 65 6c 64 73 2c 20 72 65 61 63 74 69 76 65 20 61 75 64 69 74 69 6e 67 20 6f 66 20 te.fields,.reactive.auditing.of.
6fa0 63 6f 6d 70 6c 69 63 61 74 65 64 20 6c 6f 67 00 54 68 69 73 20 69 73 20 69 6e 20 63 6f 6e 74 72 complicated.log.This.is.in.contr
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7080 7c 0a 00 00 2c 0a 00 00 dd 09 00 00 a4 09 00 00 a3 09 00 00 55 09 00 00 08 09 00 00 cd 08 00 00 |...,...............U...........
70a0 cc 08 00 00 b0 08 00 00 62 08 00 00 17 08 00 00 db 07 00 00 da 07 00 00 8a 07 00 00 3a 07 00 00 ........b...................:...
70c0 f1 06 00 00 f0 06 00 00 a6 06 00 00 57 06 00 00 06 06 00 00 b7 05 00 00 67 05 00 00 2a 05 00 00 ............W...........g...*...
70e0 29 05 00 00 de 04 00 00 8d 04 00 00 3f 04 00 00 f0 03 00 00 a1 03 00 00 45 03 00 00 44 03 00 00 )...........?...........E...D...
7100 f4 02 00 00 a8 02 00 00 70 02 00 00 6f 02 00 00 22 02 00 00 d4 01 00 00 83 01 00 00 3f 01 00 00 ........p...o..."...........?...
7120 3e 01 00 00 3d 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 73 >...=..........................s
7140 69 67 6e 65 72 20 68 61 73 20 74 6f 20 77 61 69 74 20 66 6f 72 20 61 6e 20 69 6e 63 6c 75 73 69 igner.has.to.wait.for.an.inclusi
7160 6f 6e 20 70 72 6f 6f 66 20 61 6e 64 20 61 20 63 6f 73 69 67 6e 65 64 20 74 72 65 65 20 68 65 61 on.proof.and.a.cosigned.tree.hea
7180 64 2e 00 43 65 72 74 69 66 69 63 61 74 65 20 54 72 61 6e 73 70 61 72 65 6e 63 79 2e 20 20 54 68 d..Certificate.Transparency...Th
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71c0 69 64 65 20 6c 6f 77 2d 6c 61 74 65 6e 63 79 2e 20 20 41 00 72 65 71 75 65 73 74 20 69 73 20 61 ide.low-latency...A.request.is.a
71e0 63 63 65 70 74 65 64 2e 20 20 54 68 65 72 65 20 61 72 65 20 68 6f 77 65 76 65 72 20 6e 6f 20 5f ccepted...There.are.however.no._
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7220 6e 00 41 20 73 69 67 73 75 6d 20 6c 6f 67 20 5f 74 72 69 65 73 5f 20 74 6f 20 69 6e 63 6f 72 70 n.A.sigsum.log._tries_.to.incorp
7240 6f 72 61 74 65 20 61 20 6c 65 61 66 20 69 6e 74 6f 20 69 74 73 20 4d 65 72 6b 6c 65 20 74 72 65 orate.a.leaf.into.its.Merkle.tre
7260 65 20 69 66 20 61 20 6c 6f 67 67 69 6e 67 00 00 6d 61 6e 61 67 65 6d 65 6e 74 2e 20 20 4f 75 72 e.if.a.logging..management...Our
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72a0 75 73 61 67 65 5f 2e 00 6d 6f 72 65 20 63 6f 6d 70 6c 65 78 20 74 68 61 6e 20 74 68 61 74 2e 20 usage_..more.complex.than.that..
72c0 20 41 20 73 65 70 61 72 61 74 65 20 70 72 6f 6a 65 63 74 20 73 68 6f 75 6c 64 20 66 6f 63 75 73 .A.separate.project.should.focus
72e0 20 6f 6e 20 74 72 61 6e 73 70 61 72 65 6e 74 20 6b 65 79 00 41 20 73 69 67 6e 65 72 27 73 20 64 .on.transparent.key.A.signer's.d
7300 6f 6d 61 69 6e 20 68 69 6e 74 20 69 73 20 6e 6f 74 20 70 61 72 74 20 6f 66 20 74 68 65 20 6c 6f omain.hint.is.not.part.of.the.lo
7320 67 67 65 64 20 6c 65 61 66 20 62 65 63 61 75 73 65 20 6b 65 79 20 6d 61 6e 61 67 65 6d 65 6e 74 gged.leaf.because.key.management
7340 20 69 73 00 00 20 20 20 20 20 20 20 20 5b 63 6f 73 6d 69 63 20 72 61 79 73 5d 28 68 74 74 70 73 .is..........[cosmic.rays](https
7360 3a 2f 2f 67 72 6f 75 70 73 2e 67 6f 6f 67 6c 65 2e 63 6f 6d 2f 61 2f 63 68 72 6f 6d 69 75 6d 2e ://groups.google.com/a/chromium.
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73a0 00 6d 6f 72 65 20 74 68 61 6e 20 6f 6e 65 20 6c 6f 67 20 74 6f 20 62 65 20 72 65 6c 69 61 62 6c .more.than.one.log.to.be.reliabl
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73e0 74 65 64 20 65 76 65 6e 74 73 20 6c 69 6b 65 00 77 69 74 68 6f 75 74 20 63 6f 6f 72 64 69 6e 61 ted.events.like.without.coordina
7400 74 69 6f 6e 2e 20 20 54 68 69 73 20 69 73 20 69 6d 70 6f 72 74 61 6e 74 20 62 65 63 61 75 73 65 tion...This.is.important.because
7420 20 61 20 68 65 61 6c 74 68 79 20 6c 6f 67 20 65 63 6f 73 79 73 74 65 6d 20 6e 65 65 64 73 00 74 .a.healthy.log.ecosystem.needs.t
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7460 20 63 61 6e 20 62 65 20 75 73 65 64 20 61 63 72 6f 73 73 20 73 65 76 65 72 61 6c 20 69 6e 64 65 .can.be.used.across.several.inde
7480 70 65 6e 64 65 6e 74 20 6c 6f 67 73 00 64 6f 6d 61 69 6e 20 6e 61 6d 65 2e 20 20 41 20 73 69 6e pendent.logs.domain.name...A.sin
74a0 67 6c 65 20 64 6f 6d 61 69 6e 20 6e 61 6d 65 20 69 73 20 61 6c 73 6f 20 72 65 6c 61 74 69 76 65 gle.domain.name.is.also.relative
74c0 6c 79 20 63 68 65 61 70 2e 20 20 41 6e 6f 74 68 65 72 20 62 65 6e 65 66 69 74 20 69 73 00 55 73 ly.cheap...Another.benefit.is.Us
74e0 69 6e 67 20 44 4e 53 20 74 6f 20 63 6f 6d 62 61 74 20 73 70 61 6d 20 69 73 20 63 6f 6e 76 65 6e ing.DNS.to.combat.spam.is.conven
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7520 79 20 68 61 76 65 20 61 00 00 6c 6f 67 20 69 6e 20 61 6e 79 20 73 69 67 6e 69 66 69 63 61 6e 74 y.have.a..log.in.any.significant
7540 20 77 61 79 20 69 66 20 72 61 74 65 20 6c 69 6d 69 74 73 20 61 72 65 20 6e 6f 74 20 74 6f 6f 20 .way.if.rate.limits.are.not.too.
7560 6c 6f 6f 73 65 2e 00 73 65 63 6f 6e 64 2d 6c 65 76 65 6c 20 64 6f 6d 61 69 6e 2e 20 20 59 6f 75 loose..second-level.domain...You
7580 20 77 6f 75 6c 64 20 6e 65 65 64 20 61 20 6c 61 72 67 65 20 6e 75 6d 62 65 72 20 6f 66 20 64 6f .would.need.a.large.number.of.do
75a0 6d 61 69 6e 20 6e 61 6d 65 73 20 74 6f 20 73 70 61 6d 20 74 68 65 00 64 6f 6d 61 69 6e 20 74 68 main.names.to.spam.the.domain.th
75c0 61 74 20 69 73 20 61 77 61 72 65 20 6f 66 20 74 68 65 69 72 20 76 65 72 69 66 69 63 61 74 69 6f at.is.aware.of.their.verificatio
75e0 6e 20 6b 65 79 2c 20 72 61 74 65 20 6c 69 6d 69 74 73 20 63 61 6e 20 62 65 20 61 70 70 6c 69 65 n.key,.rate.limits.can.be.applie
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7620 69 6f 6e 20 6b 65 79 20 68 61 73 68 2e 20 20 42 79 20 76 65 72 69 66 79 69 6e 67 20 74 68 61 74 ion.key.hash...By.verifying.that
7640 20 61 6c 6c 20 73 69 67 6e 65 72 73 20 63 6f 6e 74 72 6f 6c 20 61 00 72 65 73 6f 75 72 63 65 20 .all.signers.control.a.resource.
7660 72 65 63 6f 72 64 20 62 61 73 65 64 20 6f 6e 20 74 68 65 20 70 72 6f 76 69 64 65 64 20 64 6f 6d record.based.on.the.provided.dom
7680 61 69 6e 20 6e 61 6d 65 2e 20 20 54 68 65 20 64 6f 77 6e 6c 6f 61 64 65 64 20 72 65 73 75 6c 74 ain.name...The.downloaded.result
76a0 20 6d 75 73 74 00 54 68 65 20 73 69 67 6e 65 72 20 61 6c 73 6f 20 73 75 62 6d 69 74 73 20 61 20 .must.The.signer.also.submits.a.
76c0 5f 64 6f 6d 61 69 6e 20 68 69 6e 74 5f 2e 20 20 54 68 65 20 6c 6f 67 20 77 69 6c 6c 20 64 6f 77 _domain.hint_...The.log.will.dow
76e0 6e 6c 6f 61 64 20 61 20 44 4e 53 20 54 58 54 00 00 74 68 65 20 73 69 67 6e 61 74 75 72 65 20 69 nload.a.DNS.TXT..the.signature.i
7700 73 20 76 61 6c 69 64 2c 20 74 68 65 6e 20 68 61 73 68 65 73 20 69 74 20 74 6f 20 63 6f 6e 73 74 s.valid,.then.hashes.it.to.const
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7740 20 6b 65 79 2d 76 61 6c 75 65 20 70 61 69 72 73 2e 20 20 54 68 65 20 6c 6f 67 20 75 73 65 73 20 .key-value.pairs...The.log.uses.
7760 74 68 65 20 70 75 62 6c 69 63 20 76 65 72 69 66 69 63 61 74 69 6f 6e 20 6b 65 79 20 74 6f 20 63 the.public.verification.key.to.c
7780 68 65 63 6b 20 74 68 61 74 00 41 20 73 69 67 6e 65 72 20 73 75 62 6d 69 74 73 20 74 68 65 69 72 heck.that.A.signer.submits.their
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7800 20 61 72 65 20 70 72 69 6d 69 74 69 76 65 20 65 6e 6f 75 67 68 2e 00 75 73 65 73 20 61 20 73 69 .are.primitive.enough..uses.a.si
7820 6d 70 6c 65 20 41 53 43 49 49 20 66 6f 72 6d 61 74 2e 20 20 41 20 6d 6f 72 65 20 63 6f 6d 70 6c mple.ASCII.format...A.more.compl
7840 65 78 20 70 61 72 73 65 72 20 6c 69 6b 65 20 4a 53 4f 4e 20 69 73 20 6e 6f 74 20 6e 65 65 64 65 ex.parser.like.JSON.is.not.neede
7860 64 00 53 69 67 73 75 6d 20 6c 6f 67 73 20 69 6d 70 6c 65 6d 65 6e 74 20 61 6e 20 48 54 54 50 28 d.Sigsum.logs.implement.an.HTTP(
7880 53 29 20 41 50 49 2e 20 20 49 6e 70 75 74 20 61 6e 64 20 6f 75 74 70 75 74 20 69 73 20 68 75 6d S).API...Input.and.output.is.hum
78a0 61 6e 2d 72 65 61 64 61 62 6c 65 20 61 6e 64 00 23 23 23 23 20 33 2e 32 2e 32 20 2d 20 53 75 62 an-readable.and.####.3.2.2.-.Sub
78c0 6d 69 74 20 72 65 71 75 65 73 74 00 00 70 61 72 74 20 6f 66 20 61 20 64 65 66 65 6e 73 65 20 6d mit.request..part.of.a.defense.m
78e0 65 63 68 61 6e 69 73 6d 20 74 68 61 74 20 68 65 6c 70 73 20 75 73 20 63 6f 6d 62 61 74 20 6c 6f echanism.that.helps.us.combat.lo
7900 67 20 73 70 61 6d 2e 00 63 68 65 63 6b 20 74 68 61 74 20 5f 73 6f 6d 65 20 64 6f 6d 61 69 6e 5f g.spam..check.that._some.domain_
7920 20 69 73 20 61 77 61 72 65 20 6f 66 20 74 68 65 20 73 69 67 6e 65 72 27 73 20 76 65 72 69 66 69 .is.aware.of.the.signer's.verifi
7940 63 61 74 69 6f 6e 20 6b 65 79 2e 20 20 54 68 69 73 20 69 73 00 54 68 65 20 73 69 67 6e 65 72 20 cation.key...This.is.The.signer.
7960 61 6c 73 6f 20 68 61 73 20 74 6f 20 64 6f 20 61 20 6f 6e 65 2d 74 69 6d 65 20 44 4e 53 20 73 65 also.has.to.do.a.one-time.DNS.se
7980 74 75 70 2e 20 20 41 73 20 6f 75 74 6c 69 6e 65 64 20 62 65 6c 6f 77 2c 20 6c 6f 67 73 20 77 69 tup...As.outlined.below,.logs.wi
79a0 6c 6c 00 00 72 65 70 6c 61 79 65 64 20 69 6e 20 61 20 6e 6f 6e 2d 6f 76 65 72 6c 61 70 70 69 6e ll..replayed.in.a.non-overlappin
79c0 67 20 73 68 61 72 64 20 62 79 20 61 20 67 6f 6f 64 20 53 61 6d 61 72 69 74 61 6e 2e 00 69 6e 63 g.shard.by.a.good.Samaritan..inc
79e0 6f 72 70 6f 72 61 74 65 64 20 69 6e 74 6f 20 74 68 65 20 73 69 67 6e 65 64 20 73 74 61 74 65 6d orporated.into.the.signed.statem
7a00 65 6e 74 20 74 6f 20 65 6e 73 75 72 65 20 74 68 61 74 20 61 20 6c 6f 67 27 73 20 6c 65 61 76 65 ent.to.ensure.that.a.log's.leave
7a20 73 20 63 61 6e 6e 6f 74 20 62 65 00 54 68 65 20 73 65 6c 65 63 74 65 64 20 73 68 61 72 64 20 68 s.cannot.be.The.selected.shard.h
7a40 69 6e 74 20 61 6e 64 20 63 68 65 63 6b 73 75 6d 20 61 72 65 20 73 69 67 6e 65 64 20 62 79 20 74 int.and.checksum.are.signed.by.t
7a60 68 65 20 73 69 67 6e 65 72 2e 20 20 41 20 73 68 61 72 64 20 68 69 6e 74 20 69 73 00 00 68 61 73 he.signer...A.shard.hint.is..has
7a80 68 20 66 75 6e 63 74 69 6f 6e 2e 20 20 46 6f 72 20 65 78 61 6d 70 6c 65 2c 20 69 74 20 63 6f 75 h.function...For.example,.it.cou
7aa0 6c 64 20 62 65 20 74 68 65 20 68 61 73 68 20 6f 66 20 61 6e 20 65 78 65 63 75 74 61 62 6c 65 20 ld.be.the.hash.of.an.executable.
7ac0 62 69 6e 61 72 79 2e 00 61 63 74 69 76 65 20 64 75 72 69 6e 67 20 32 30 32 31 22 2e 20 20 54 68 binary..active.during.2021"...Th
7ae0 65 20 73 65 6c 65 63 74 65 64 20 63 68 65 63 6b 73 75 6d 20 69 73 20 6d 6f 73 74 20 6c 69 6b 65 e.selected.checksum.is.most.like
7b00 6c 79 20 74 68 65 20 6f 75 74 70 75 74 20 6f 66 20 61 00 73 65 6c 65 63 74 65 64 20 73 68 61 72 ly.the.output.of.a.selected.shar
7b20 64 20 68 69 6e 74 20 72 65 70 72 65 73 65 6e 74 73 20 61 6e 20 61 62 73 74 72 61 63 74 20 73 74 d.hint.represents.an.abstract.st
7b40 61 74 65 6d 65 6e 74 20 6c 69 6b 65 20 22 73 69 67 73 75 6d 20 6c 6f 67 73 20 74 68 61 74 20 61 atement.like."sigsum.logs.that.a
7b60 72 65 00 41 20 73 69 67 6e 65 72 20 73 65 6c 65 63 74 73 20 61 20 73 68 61 72 64 20 68 69 6e 74 re.A.signer.selects.a.shard.hint
7b80 20 61 6e 64 20 61 20 63 68 65 63 6b 73 75 6d 20 74 68 61 74 20 73 68 6f 75 6c 64 20 62 65 20 6c .and.a.checksum.that.should.be.l
7ba0 6f 67 67 65 64 2e 20 20 54 68 65 00 23 23 23 23 20 33 2e 32 2e 31 20 2d 20 50 72 65 70 61 72 65 ogged...The.####.3.2.1.-.Prepare
7bc0 20 61 20 72 65 71 75 65 73 74 00 23 23 23 20 33 2e 32 20 2d 20 55 73 61 67 65 20 70 61 74 74 65 .a.request.###.3.2.-.Usage.patte
7be0 72 6e 00 00 6f 74 68 65 72 20 77 6f 72 64 73 2c 20 76 65 72 69 66 69 65 72 73 20 61 6e 64 20 6d rn..other.words,.verifiers.and.m
7c00 6f 6e 69 74 6f 72 73 20 6d 75 73 74 20 6c 6f 63 61 74 65 20 6b 65 79 73 20 61 6e 64 20 74 72 75 onitors.must.locate.keys.and.tru
7c20 73 74 20 74 68 65 6d 20 65 78 70 6c 69 63 69 74 6c 79 2e 00 74 68 65 20 6c 69 6b 65 6c 69 68 6f st.them.explicitly..the.likeliho
7c40 6f 64 20 74 68 61 74 20 61 6e 20 75 6e 74 72 75 73 74 65 64 20 6b 65 79 20 69 73 20 64 69 73 63 od.that.an.untrusted.key.is.disc
7c60 6f 76 65 72 65 64 20 61 6e 64 20 75 73 65 64 20 62 79 20 6d 69 73 74 61 6b 65 2e 20 20 49 6e 00 overed.and.used.by.mistake...In.
7c80 4e 6f 74 65 20 74 68 61 74 20 61 20 6b 65 79 20 68 61 73 68 20 69 73 20 6c 6f 67 67 65 64 20 72 Note.that.a.key.hash.is.logged.r
7ca0 61 74 68 65 72 20 74 68 61 6e 20 74 68 65 20 70 75 62 6c 69 63 20 6b 65 79 20 69 74 73 65 6c 66 ather.than.the.public.key.itself
7cc0 2e 20 20 54 68 69 73 20 72 65 64 75 63 65 73 00 00 64 61 74 61 20 74 68 61 74 20 61 20 63 68 65 ...This.reduces..data.that.a.che
7ce0 63 6b 73 75 6d 20 72 65 70 72 65 73 65 6e 74 73 2e 20 20 57 68 65 72 65 20 64 61 74 61 20 69 73 cksum.represents...Where.data.is
7d00 20 6c 6f 63 61 74 65 64 20 69 73 20 75 73 65 2d 63 61 73 65 20 73 70 65 63 69 66 69 63 2e 00 41 .located.is.use-case.specific..A
7d20 6e 79 20 61 64 64 69 74 69 6f 6e 61 6c 20 6d 65 74 61 64 61 74 61 20 74 68 61 74 20 69 73 20 75 ny.additional.metadata.that.is.u
7d40 73 65 2d 63 61 73 65 20 73 70 65 63 69 66 69 63 20 63 61 6e 20 62 65 20 73 74 6f 72 65 64 20 61 se-case.specific.can.be.stored.a
7d60 73 20 70 61 72 74 20 6f 66 20 74 68 65 00 00 6e 6f 6e 2d 6f 76 65 72 6c 61 70 70 69 6e 67 20 73 s.part.of.the..non-overlapping.s
7d80 68 61 72 64 2e 20 20 53 65 65 20 64 65 74 61 69 6c 73 20 69 6e 20 53 65 63 74 69 6f 6e 20 34 2e hard...See.details.in.Section.4.
7da0 32 2e 00 41 20 73 68 61 72 64 20 68 69 6e 74 20 69 73 20 69 6e 63 6c 75 64 65 64 20 69 6e 20 74 2..A.shard.hint.is.included.in.t
7dc0 68 65 20 73 69 67 6e 65 64 20 73 74 61 74 65 6d 65 6e 74 20 74 6f 20 70 72 65 76 65 6e 74 20 72 he.signed.statement.to.prevent.r
7de0 65 70 6c 61 79 73 20 69 6e 20 61 00 00 62 65 20 75 73 65 64 20 74 6f 20 76 65 72 69 66 79 20 74 eplays.in.a..be.used.to.verify.t
7e00 68 65 20 73 69 67 6e 61 74 75 72 65 2e 00 2d 20 2a 2a 6b 65 79 5f 68 61 73 68 2a 2a 3a 20 61 20 he.signature..-.**key_hash**:.a.
7e20 63 72 79 70 74 6f 67 72 61 70 68 69 63 20 68 61 73 68 20 6f 66 20 74 68 65 20 73 69 67 6e 65 72 cryptographic.hash.of.the.signer
7e40 27 73 20 76 65 72 69 66 69 63 61 74 69 6f 6e 20 6b 65 79 20 74 68 61 74 20 63 61 6e 00 6c 65 61 's.verification.key.that.can.lea
7e60 66 27 73 20 73 68 61 72 64 20 68 69 6e 74 20 61 6e 64 20 63 68 65 63 6b 73 75 6d 2e 00 2d 20 2a f's.shard.hint.and.checksum..-.*
7e80 2a 73 69 67 6e 61 74 75 72 65 2a 2a 3a 20 61 20 64 69 67 69 74 61 6c 20 73 69 67 6e 61 74 75 72 *signature**:.a.digital.signatur
7ea0 65 20 74 68 61 74 20 69 73 20 63 6f 6d 70 75 74 65 64 20 62 79 20 61 20 73 69 67 6e 65 72 20 6f e.that.is.computed.by.a.signer.o
7ec0 76 65 72 20 74 68 65 00 6a 75 73 74 20 63 68 65 63 6b 73 75 6d 73 2e 00 2d 20 2a 2a 63 68 65 63 ver.the.just.checksums..-.**chec
7ee0 6b 73 75 6d 2a 2a 3a 20 6d 6f 73 74 20 6c 69 6b 65 6c 79 20 61 20 68 61 73 68 20 6f 66 20 73 6f ksum**:.most.likely.a.hash.of.so
7f00 6d 65 20 64 61 74 61 2e 20 20 54 68 65 20 6c 6f 67 20 69 73 20 6e 6f 74 20 61 77 61 72 65 20 6f me.data...The.log.is.not.aware.o
7f20 66 20 64 61 74 61 3b 00 61 72 65 20 61 63 63 65 70 74 65 64 2e 20 20 4f 6e 63 65 20 65 6c 61 70 f.data;.are.accepted...Once.elap
7f40 73 65 64 2c 20 74 68 65 20 6c 6f 67 20 63 61 6e 20 62 65 20 73 68 75 74 20 64 6f 77 6e 2e 00 53 sed,.the.log.can.be.shut.down..S
7f60 68 61 72 64 69 6e 67 20 6d 65 61 6e 73 20 74 68 61 74 20 74 68 65 20 6c 6f 67 20 68 61 73 20 61 harding.means.that.the.log.has.a
7f80 20 70 72 65 64 65 66 69 6e 65 64 20 74 69 6d 65 20 64 75 72 69 6e 67 20 77 68 69 63 68 20 6c 6f .predefined.time.during.which.lo
7fa0 67 67 69 6e 67 20 72 65 71 75 65 73 74 73 00 2d 20 2a 2a 73 68 61 72 64 5f 68 69 6e 74 2a 2a 3a gging.requests.-.**shard_hint**:
7fc0 20 61 20 6e 75 6d 62 65 72 20 74 68 61 74 20 62 69 6e 64 73 20 74 68 65 20 6c 65 61 66 20 74 6f .a.number.that.binds.the.leaf.to
7fe0 20 61 20 70 61 72 74 69 63 75 6c 61 72 20 5f 73 68 61 72 64 20 69 6e 74 65 72 76 61 6c 5f 2e 00 .a.particular._shard.interval_..
8000 61 64 00 00 23 00 00 00 4f 01 00 00 00 10 00 00 44 00 00 00 00 00 00 00 d8 0f 00 00 87 0f 00 00 ad..#...O.......D...............
8020 3c 0f 00 00 ec 0e 00 00 9c 0e 00 00 9b 0e 00 00 4e 0e 00 00 fe 0d 00 00 d5 0d 00 00 8e 0d 00 00 <...............N...............
8040 45 0d 00 00 f6 0c 00 00 97 0c 00 00 96 0c 00 00 4d 0c 00 00 4c 0c 00 00 32 0c 00 00 e5 0b 00 00 E...............M...L...2.......
8060 95 0b 00 00 55 0b 00 00 54 0b 00 00 4a 0b 00 00 07 0b 00 00 06 0b 00 00 f8 0a 00 00 ac 0a 00 00 ....U...T...J...................
8080 5f 0a 00 00 5e 0a 00 00 53 0a 00 00 19 0a 00 00 18 0a 00 00 fe 09 00 00 b3 09 00 00 75 09 00 00 _...^...S...................u...
80a0 2d 09 00 00 e4 08 00 00 cf 08 00 00 81 08 00 00 80 08 00 00 36 08 00 00 e5 07 00 00 95 07 00 00 -...................6...........
80c0 49 07 00 00 fa 06 00 00 b9 06 00 00 b8 06 00 00 a0 06 00 00 4e 06 00 00 00 06 00 00 b1 05 00 00 I...................N...........
80e0 61 05 00 00 60 05 00 00 10 05 00 00 bd 04 00 00 6d 04 00 00 1f 04 00 00 d4 03 00 00 d3 03 00 00 a...`...........m...............
8100 c1 03 00 00 74 03 00 00 23 03 00 00 da 02 00 00 8c 02 00 00 40 02 00 00 3f 02 00 00 f0 01 00 00 ....t...#...........@...?.......
8120 9f 01 00 00 4f 01 00 00 4e 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ....O...N.......................
8140 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 4e 6f 20 64 61 74 61 20 61 6e 64 20 72 69 63 68 20 ...............No.data.and.rich.
8160 6d 65 74 61 64 61 74 61 20 69 73 20 6c 6f 67 67 65 64 20 74 6f 20 70 72 6f 74 65 63 74 20 74 68 metadata.is.logged.to.protect.th
8180 65 20 6c 6f 67 20 6f 70 65 72 61 74 6f 72 20 66 72 6f 6d 20 70 6f 69 73 6f 6e 69 6e 67 2e 00 41 e.log.operator.from.poisoning..A
81a0 50 49 2e 20 20 41 20 73 69 67 6e 65 72 20 6d 75 73 74 20 70 72 6f 76 65 20 74 68 61 74 20 74 68 PI...A.signer.must.prove.that.th
81c0 65 79 20 6f 77 6e 20 61 20 64 6f 6d 61 69 6e 20 6e 61 6d 65 20 61 73 20 61 6e 20 61 6e 74 69 2d ey.own.a.domain.name.as.an.anti-
81e0 73 70 61 6d 20 6d 65 63 68 61 6e 69 73 6d 2e 00 53 69 67 6e 65 72 73 2c 20 6d 6f 6e 69 74 6f 72 spam.mechanism..Signers,.monitor
8200 73 2c 20 61 6e 64 20 77 69 74 6e 65 73 73 65 73 20 69 6e 74 65 72 61 63 74 20 77 69 74 68 20 74 s,.and.witnesses.interact.with.t
8220 68 65 20 6c 6f 67 73 20 75 73 69 6e 67 20 61 6e 20 41 53 43 49 49 20 48 54 54 50 28 53 29 00 00 he.logs.using.an.ASCII.HTTP(S)..
8240 68 65 61 64 20 69 73 20 63 6f 72 72 65 63 74 20 62 65 66 6f 72 65 20 63 6f 73 69 67 6e 69 6e 67 head.is.correct.before.cosigning
8260 2e 20 20 43 6f 72 72 65 63 74 20 72 65 66 65 72 73 20 74 6f 20 66 72 65 73 68 20 61 6e 64 20 61 ...Correct.refers.to.fresh.and.a
8280 70 70 65 6e 64 2d 6f 6e 6c 79 2e 00 63 6f 6e 74 72 6f 6c 6c 69 6e 67 20 65 6e 6f 75 67 68 20 69 ppend-only..controlling.enough.i
82a0 6e 64 65 70 65 6e 64 65 6e 74 20 77 69 74 6e 65 73 73 65 73 2e 20 20 41 20 77 69 74 6e 65 73 73 ndependent.witnesses...A.witness
82c0 20 63 68 65 63 6b 73 20 74 68 61 74 20 61 20 6c 6f 67 27 73 20 74 72 65 65 00 54 68 65 20 64 69 .checks.that.a.log's.tree.The.di
82e0 66 66 69 63 75 6c 74 79 20 6f 66 20 62 79 70 61 73 73 69 6e 67 20 70 75 62 6c 69 63 20 6c 6f 67 fficulty.of.bypassing.public.log
8300 67 69 6e 67 20 69 73 20 62 61 73 65 64 20 6f 6e 20 74 68 65 20 64 69 66 66 69 63 75 6c 74 79 20 ging.is.based.on.the.difficulty.
8320 6f 66 00 73 68 75 74 20 64 6f 77 6e 20 5f 73 61 66 65 6c 79 5f 20 62 65 63 61 75 73 65 20 76 65 of.shut.down._safely_.because.ve
8340 72 69 66 69 63 61 74 69 6f 6e 20 6f 6e 20 74 68 65 20 76 65 72 69 66 69 65 72 2d 73 69 64 65 20 rification.on.the.verifier-side.
8360 69 73 20 6e 6f 74 20 69 6e 74 65 72 61 63 74 69 76 65 2e 00 53 69 67 73 75 6d 20 6c 6f 67 73 20 is.not.interactive..Sigsum.logs.
8380 61 72 65 20 73 68 61 72 64 65 64 20 61 6e 64 20 73 68 75 74 20 64 6f 77 6e 20 61 74 20 70 72 65 are.sharded.and.shut.down.at.pre
83a0 64 65 66 69 6e 65 64 20 74 69 6d 65 73 2e 20 20 41 20 73 69 67 73 75 6d 20 6c 6f 67 20 63 61 6e defined.times...A.sigsum.log.can
83c0 00 23 23 23 20 33 2e 33 20 2d 20 53 75 6d 6d 61 72 79 00 00 61 67 61 69 6e 73 74 20 61 20 73 69 .###.3.3.-.Summary..against.a.si
83e0 67 6e 65 72 27 73 20 64 69 73 74 72 69 62 75 74 65 64 20 69 6e 66 72 61 73 74 72 75 63 74 75 72 gner's.distributed.infrastructur
8400 65 2e 20 20 41 20 6d 6f 6e 69 74 6f 72 20 6d 61 79 20 64 65 74 65 63 74 20 74 68 61 74 2e 00 73 e...A.monitor.may.detect.that..s
8420 65 72 76 65 20 70 72 6f 6f 66 73 20 6f 66 20 70 75 62 6c 69 63 20 6c 6f 67 67 69 6e 67 20 63 6f erve.proofs.of.public.logging.co
8440 75 6c 64 20 69 6e 64 69 63 61 74 65 20 74 68 61 74 20 74 68 65 72 65 20 69 73 20 61 6e 20 6f 6e uld.indicate.that.there.is.an.on
8460 67 6f 69 6e 67 20 61 74 74 61 63 6b 00 69 6e 20 53 65 63 74 69 6f 6e 20 33 2e 32 2e 35 2e 20 20 going.attack.in.Section.3.2.5...
8480 46 6f 72 20 65 78 61 6d 70 6c 65 2c 20 74 68 65 20 66 61 63 74 20 74 68 61 74 20 61 20 64 69 73 For.example,.the.fact.that.a.dis
84a0 74 72 69 62 75 74 69 6f 6e 20 6d 65 63 68 61 6e 69 73 6d 20 64 6f 65 73 20 6e 6f 74 00 65 76 65 tribution.mechanism.does.not.eve
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84e0 66 6f 72 63 69 6e 67 20 74 68 65 20 74 68 69 72 64 20 61 6e 64 20 66 6f 75 72 74 68 20 63 72 69 forcing.the.third.and.fourth.cri
8500 74 65 72 69 61 20 70 61 72 74 69 61 6c 6c 79 00 49 74 20 73 68 6f 75 6c 64 20 61 6c 73 6f 20 62 teria.partially.It.should.also.b
8520 65 20 6e 6f 74 65 64 20 74 68 61 74 20 73 69 67 73 75 6d 20 6c 6f 67 67 69 6e 67 20 63 61 6e 20 e.noted.that.sigsum.logging.can.
8540 66 61 63 69 6c 69 74 61 74 65 20 64 65 74 65 63 74 69 6f 6e 20 6f 66 20 61 74 74 61 63 6b 73 00 facilitate.detection.of.attacks.
8560 00 6d 61 79 20 61 6c 73 6f 20 6e 65 65 64 20 74 6f 20 62 65 20 61 77 61 72 65 20 6f 66 20 68 6f .may.also.need.to.be.aware.of.ho
8580 77 20 74 6f 20 6c 6f 63 61 74 65 20 74 68 65 20 64 61 74 61 20 74 68 61 74 20 61 20 63 68 65 63 w.to.locate.the.data.that.a.chec
85a0 6b 73 75 6d 20 72 65 70 72 65 73 65 6e 74 73 2e 00 73 70 65 63 69 66 69 63 20 69 6e 20 73 69 67 ksum.represents..specific.in.sig
85c0 73 75 6d 2e 20 20 41 74 20 6d 69 6e 69 6d 75 6d 2c 20 79 6f 75 20 6e 65 65 64 20 74 6f 20 6c 6f sum...At.minimum,.you.need.to.lo
85e0 63 61 74 65 20 72 65 6c 65 76 61 6e 74 20 70 75 62 6c 69 63 20 6b 65 79 73 2e 20 20 59 6f 75 00 cate.relevant.public.keys...You.
8600 74 72 61 63 6b 20 6f 66 20 77 68 61 74 20 61 70 70 65 61 72 73 20 69 6e 20 74 68 65 20 70 75 62 track.of.what.appears.in.the.pub
8620 6c 69 63 20 6c 6f 67 73 2e 20 20 4d 6f 6e 69 74 6f 72 69 6e 67 20 69 73 20 6e 65 63 65 73 73 61 lic.logs...Monitoring.is.necessa
8640 72 69 6c 79 20 75 73 65 2d 63 61 73 65 00 41 6e 20 6f 66 74 65 6e 20 6f 76 65 72 6c 6f 6f 6b 65 rily.use-case.An.often.overlooke
8660 64 20 73 74 65 70 20 69 73 20 74 68 61 74 20 74 72 61 6e 73 70 61 72 65 6e 63 79 20 6c 6f 67 67 d.step.is.that.transparency.logg
8680 69 6e 67 20 66 61 6c 6c 73 20 73 68 6f 72 74 20 69 66 20 6e 6f 2d 6f 6e 65 20 6b 65 65 70 73 00 ing.falls.short.if.no-one.keeps.
86a0 23 23 23 23 20 33 2e 32 2e 36 20 2d 20 4d 6f 6e 69 74 6f 72 69 6e 67 00 00 75 6e 6c 65 73 73 20 ####.3.2.6.-.Monitoring..unless.
86c0 74 68 65 20 61 74 74 61 63 6b 65 72 20 63 6f 6e 74 72 6f 6c 73 20 6d 6f 72 65 20 74 68 61 6e 20 the.attacker.controls.more.than.
86e0 61 20 74 68 72 65 73 68 6f 6c 64 20 6f 66 20 77 69 74 6e 65 73 73 65 73 2e 00 74 72 69 63 6b 65 a.threshold.of.witnesses..tricke
8700 64 20 69 6e 74 6f 20 61 63 63 65 70 74 69 6e 67 20 73 6f 6d 65 20 64 61 74 61 20 77 68 6f 73 65 d.into.accepting.some.data.whose
8720 20 63 68 65 63 6b 73 75 6d 20 68 61 76 65 20 79 65 74 20 74 6f 20 62 65 20 70 75 62 6c 69 63 6c .checksum.have.yet.to.be.publicl
8740 79 20 6c 6f 67 67 65 64 00 75 73 69 6e 67 20 61 20 76 61 72 69 61 6e 74 20 6f 66 20 77 69 74 6e y.logged.using.a.variant.of.witn
8760 65 73 73 20 63 6f 73 69 67 6e 69 6e 67 2e 20 20 49 6e 20 6f 74 68 65 72 20 77 6f 72 64 73 2c 20 ess.cosigning...In.other.words,.
8780 61 20 76 65 72 69 66 69 65 72 20 63 61 6e 6e 6f 74 20 62 65 00 61 6e 20 69 6e 63 6c 75 73 69 6f a.verifier.cannot.be.an.inclusio
87a0 6e 20 70 72 6f 6f 66 20 6c 65 61 64 73 20 75 70 20 74 6f 2e 20 20 53 69 67 73 75 6d 20 6c 6f 67 n.proof.leads.up.to...Sigsum.log
87c0 73 20 68 61 76 65 20 74 72 75 73 74 77 6f 72 74 68 79 20 74 72 65 65 20 68 65 61 64 73 20 64 75 s.have.trustworthy.tree.heads.du
87e0 65 20 74 6f 00 54 68 65 72 65 66 6f 72 65 2c 20 61 20 70 72 6f 6f 66 20 6f 66 20 70 75 62 6c 69 e.to.Therefore,.a.proof.of.publi
8800 63 20 6c 6f 67 67 69 6e 67 20 69 73 20 6f 6e 6c 79 20 61 73 20 63 6f 6e 76 69 6e 63 69 6e 67 20 c.logging.is.only.as.convincing.
8820 61 73 20 74 68 65 20 74 72 65 65 20 68 65 61 64 20 74 68 61 74 00 4e 6f 74 69 63 65 20 74 68 61 as.the.tree.head.that.Notice.tha
8840 74 20 74 68 65 72 65 20 61 72 65 20 6e 6f 20 6e 65 77 20 6f 75 74 62 6f 75 6e 64 20 6e 65 74 77 t.there.are.no.new.outbound.netw
8860 6f 72 6b 20 63 6f 6e 6e 65 63 74 69 6f 6e 73 20 66 6f 72 20 61 20 76 65 72 69 66 69 65 72 2e 00 ork.connections.for.a.verifier..
8880 00 34 2e 20 54 68 65 20 70 72 6f 76 69 64 65 64 20 74 72 65 65 20 68 65 61 64 20 69 73 20 66 72 .4..The.provided.tree.head.is.fr
88a0 6f 6d 20 61 20 6b 6e 6f 77 6e 20 6c 6f 67 20 77 69 74 68 20 65 6e 6f 75 67 68 20 76 61 6c 69 64 om.a.known.log.with.enough.valid
88c0 20 63 6f 73 69 67 6e 61 74 75 72 65 73 2e 00 69 74 73 20 69 6e 63 6c 75 73 69 6f 6e 20 70 72 6f .cosignatures..its.inclusion.pro
88e0 6f 66 2e 00 33 2e 20 54 68 65 20 70 72 6f 76 69 64 65 64 20 74 72 65 65 20 68 65 61 64 20 63 61 of..3..The.provided.tree.head.ca
8900 6e 20 62 65 20 72 65 63 6f 6e 73 74 72 75 63 74 65 64 20 66 72 6f 6d 20 74 68 65 20 6c 6f 67 67 n.be.reconstructed.from.the.logg
8920 65 64 20 6c 65 61 66 20 61 6e 64 20 00 32 2e 20 54 68 65 20 73 69 67 6e 65 72 27 73 20 73 69 67 ed.leaf.and..2..The.signer's.sig
8940 6e 65 64 20 73 74 61 74 65 6d 65 6e 74 20 69 73 20 76 61 6c 69 64 20 66 6f 72 20 74 68 65 20 73 ned.statement.is.valid.for.the.s
8960 70 65 63 69 66 69 65 64 20 70 75 62 6c 69 63 20 6b 65 79 2e 00 31 2e 20 54 68 65 20 73 69 67 6e pecified.public.key..1..The.sign
8980 65 72 27 73 20 63 68 65 63 6b 73 75 6d 20 69 73 20 63 6f 72 72 65 63 74 20 66 6f 72 20 74 68 65 er's.checksum.is.correct.for.the
89a0 20 64 69 73 74 72 69 62 75 74 65 64 20 64 61 74 61 2e 00 41 20 76 65 72 69 66 69 65 72 20 73 68 .distributed.data..A.verifier.sh
89c0 6f 75 6c 64 20 6f 6e 6c 79 20 61 63 63 65 70 74 20 74 68 65 20 64 69 73 74 72 69 62 75 74 65 64 ould.only.accept.the.distributed
89e0 20 64 61 74 61 20 69 66 20 74 68 65 73 65 20 63 72 69 74 65 72 69 61 20 68 6f 6c 64 3a 00 23 23 .data.if.these.criteria.hold:.##
8a00 23 23 20 33 2e 32 2e 35 20 2d 20 56 65 72 69 66 69 63 61 74 69 6f 6e 00 00 61 6e 20 69 6e 63 6c ##.3.2.5.-.Verification..an.incl
8a20 75 73 69 6f 6e 20 70 72 6f 6f 66 20 74 68 61 74 20 6c 65 61 64 73 20 75 70 20 74 6f 20 61 20 63 usion.proof.that.leads.up.to.a.c
8a40 6f 73 69 67 6e 65 64 20 74 72 65 65 20 68 65 61 64 2e 00 2a 2a 50 72 6f 6f 66 3a 2a 2a 00 00 63 osigned.tree.head..**Proof:**..c
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