Support calculating root from consistency proof #140
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This is useful for other teams in the transparency space and was requested via the transparency-dev Slack channel. The new method is similar in essence to RootFromInclusionProof so fits in within the API. As noted in the CHANGELOG, this change fixes a logical bug in the previous code that would have successfully verified an _empty_ proof from a tree size of 0 to any other tree size. In this change, trying to verify a consistency from a tree size of 0 to any other size than 0 will be considered an error, no matter what proof is provided.
AlCutter
reviewed
Sep 18, 2024
Codecov ReportAll modified and coverable lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## main #140 +/- ##
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- Coverage 89.33% 86.93% -2.41%
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Files 7 7
Lines 497 375 -122
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- Hits 444 326 -118
+ Misses 48 44 -4
Partials 5 5 ☔ View full report in Codecov by Sentry. |
Also updated comment on VerifyConsistency to say size1 is required to be > 0. The function is only clearly defined in this case. It's now undefined where size1 is 0.
AlCutter
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Sep 18, 2024
This was referenced Sep 18, 2024
mhutchinson
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The tests show that this currently works, providing that the proof is empty. When the merkle library is updated to pull in transparency-dev/merkle#140, this will fail too. In both of the new test cases, the witness should ratchet forward when a new checkpoint is provided. As a separate note, I recommend rewriting these tests at some near point in the future. They are currently quite brittle as they rely on hard coded test data with no obvious script to update them. An in-memory test log would be a great way to generate the test data in a flexible way.
mhutchinson
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* Added tests for witnesses updating from tree size 0 The tests show that this currently works, providing that the proof is empty. When the merkle library is updated to pull in transparency-dev/merkle#140, this will fail too. In both of the new test cases, the witness should ratchet forward when a new checkpoint is provided. As a separate note, I recommend rewriting these tests at some near point in the future. They are currently quite brittle as they rely on hard coded test data with no obvious script to update them. An in-memory test log would be a great way to generate the test data in a flexible way. * Support ratcheting forward from checkpoints for size 0 The only way to handle this is via a special case.
mhutchinson
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This is primarily to pull in transparency-dev/merkle#140 now to confirm it doesn't have any suprises while I'm still context loaded on the issue. Better that than it surprising someone down the road.
mhutchinson
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This is primarily to pull in transparency-dev/merkle#140 now to confirm it doesn't have any suprises while I'm still context loaded on the issue. Better that than it surprising someone down the road.
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This is useful for other teams in the transparency space and was requested via the transparency-dev Slack channel. The new method is similar in essence to RootFromInclusionProof so fits in within the API.
As noted in the CHANGELOG, this change fixes a logical bug in the previous code that would have successfully verified an empty proof from a tree size of 0 to any other tree size. In this change, trying to verify a consistency from a tree size of 0 to any other size than 0 will be considered an error, no matter what proof is provided.