fix: signature verification due to leading zeros #326
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According to FIPS 186-5, section 6.4.2 ECDSA Signature
Verification Algorithm, the hash of the message must be adjusted
based on the order n of the base point of the elliptic curve:
If log2(n) ≥ hashlen, set E = H. Otherwise, set E equal to
the leftmost log2(n) bits of H.
Unfortunately because elliptic converts messages to BN instances the
reported `byteLength()` for the message can be incorrect if the message
has 8 or more leading zero bits.
Here we fix it by:
1. Counting leading zeroes in hex strings provided as messages
2. Counting all array entries in Array-like (e.g. Buffer)
messages
3. Providing an `msgBitLength` option to both `.sign`/`.verify` to let
user override the behavior
Original PR: #322
Credit: @Markus-MS
paulmillr
approved these changes
Oct 25, 2024
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Who would use |
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@paulmillr thanks for the review! I just wanted to provide an escape hatch for people whom this patch broke 😭 |
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Published in 6.6.0. Thank you! |
This was referenced Oct 28, 2024
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According to FIPS 186-5, section 6.4.2 ECDSA Signature Verification Algorithm, the hash of the message must be adjusted based on the order n of the base point of the elliptic curve:
Unfortunately because elliptic converts messages to BN instances the reported
byteLength()for the message can be incorrect if the message has 8 or more leading zero bits.Here we fix it by:
msgBitLengthoption to both.sign/.verifyto let user override the behaviorOriginal PR: #322
Credit: @Markus-MS