Check the hash size during proof verification [ECR-3687]

[dmitry-timofeev]

Overview

Check that all hashes are SHA-256 hashes (32-byte long).

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See: https://jira.bf.local/browse/ECR-3687

Definition of Done

• There are no TODOs left in the code
• Change is covered by automated tests
• The coding guidelines are followed
• Public API has Javadoc
• Method preconditions are checked and documented in the Javadoc of the method
• Changelog is updated if needed (in case of notable or breaking changes)
• The continuous integration build passes

[coveralls]

Coverage increased (+0.09%) to 85.954% when pulling 570b76b on dmitry-timofeev:enforce-hash-size-ECR-3687 into 72ea871 on exonum:dynamic-services.

[MakarovS]

👍

[MakarovS]

Can't we check it later and avoid additional traverse through proof? Check this in #verifyEmptyRangeProof and #indexHashedEntriesByHeight? Or is it an unnecessary optimization?

[dmitry-timofeev]

We can, but that would require duplicating the code in both branches. I don't think it will have a significant impact, as the earlier profile showed that hashing takes most of the time. #1163 could tell the numbers.

[dmitry-timofeev]

It is literally noise:

(no verification)

Benchmark                      (height)   Mode  Cnt   Score   Error   Units
FlatListProofBenchmark.verify        20  thrpt   10  46,506 ? 0,212  ops/ms

(with verification, flat-list-verify-benchmark-with-hash-checks-ECR-3608)

Benchmark                      (height)   Mode  Cnt   Score   Error   Units
FlatListProofBenchmark.verify        20  thrpt   10  46,407 ? 0,230  ops/ms