Compare MACs in constant time #143
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The PASETO spec requires MACs to be compared in constant time to combat timing leaks. This commit replaces MAC comparisons using `bytes.__eq__` with calls to `hmac.compare_digest`, which is the standard library function intended for that purpose.
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Thanks for the PR! I should have used |
Codecov Report
@@ Coverage Diff @@
## main #143 +/- ##
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Coverage 98.75% 98.75%
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Files 14 14
Lines 1364 1365 +1
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+ Hits 1347 1348 +1
Misses 17 17
Continue to review full report at Codecov.
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Thanks for the quick turn-around time! |
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@MatthiasValvekens I've released v1.6.8 including your contribution! |
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This PR replaces MAC comparisons using
bytes.__eq__with calls tohmac.compare_digestin the decryption routines forv1,v3andv4, since the PASETO spec requires MACs to be checked in constant time. Thev2handler delegates this check todecrypt_and_verifyin PyCryptoDome, which uses a randomised MAC comparison strategy instead. As such,v2didn't require any fixes.Comments certainly welcome!