Optimize hash_pbkdf2() by reusing HMAC contexts#21175
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gregharmon wants to merge 5 commits intophp:masterfrom
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Optimize hash_pbkdf2() by reusing HMAC contexts#21175gregharmon wants to merge 5 commits intophp:masterfrom
gregharmon wants to merge 5 commits intophp:masterfrom
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TimWolla
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Since this is security-sensitive code: Can you please split the individual optimizations into separate commits for ease of review?
- Migration from float to integer operations to calculate the digest lengths.
- HMAC context reuse
- SHA-256 special case
- CommonCrypto SHA-256 special case
- Possibly other individually useful migration steps that I missed
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TimWolla
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Thank you for splitting the commits. Some more superficial review. I'll need to take a deeper look at the logic when it isn't almost midnight.
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Fixes #9604.
Optimize
hash_pbkdf2()inext/hashby reusing precomputed HMAC contexts instead of rehashing key blocks each round.Changes
ext/hash/tests/gh9604.phpt.Behavior
No API or semantic changes intended: validation, return formats, and output bytes are unchanged.
Tests
make test TESTS="ext/hash/tests/hash_pbkdf2_basic.phpt ext/hash/tests/hash_pbkdf2_error.phpt ext/hash/tests/gh9604.phpt"make test TESTS="ext/hash/tests"Benchmark
Setup:
hash_pbkdf2('sha256', 'password', 'salt', 200000, 64, false)hrtime(true), median reportedObserved on this machine:
135.47 msmedian28.28 msmedian-of-12 (sample medians27.68–28.46 ms)~4.79x