Restrict P256EncryptPublic::from_bytes and P256SignPublic::from_bytes to uncompressed format only
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r-n-o
changed the title
P256EncryptPublic::from_bytes to uncompressed format onlyP256EncryptPublic::from_bytes and P256SignPublic::from_bytes to uncompressed format only
cr-tk
approved these changes
Dec 23, 2024
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The code changes look good to me 👍
As discussed out-of-band, the length checks rely on specific behavior in the elliptic-curve and sec1 crates behind from_sec1_bytes() to not accept a 65 byte long "uncompressed"-pubkey-sized input that claims to be a an "compressed" input via the tag, and bypass our external check that way. This validation appears to be in place upstream in sec1 v0.3.0 (see from_bytes() in src/point.rs), so I think this assumption is valid 🙂
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I've bumped QOS in mono to the tip of this branch and ran tests to verify that we're not relying on |
moe-dev
approved these changes
Jan 2, 2025
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Summary & Motivation (Problem vs. Solution)
This was found by @cr-tk during fuzz testing: the documentation of
P256EncryptPublic::from_bytesandP256SignPublic::from_bytesdo not match their actual behavior. For consistency's sake I'm making these methods accept only uncompressed SEC1 bytes.How I Tested These Changes
Existing + new unit tests