fix(pkcs12): validate kdf iteration count >= 1#2285
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baloo merged 1 commit intoRustCrypto:masterfrom Apr 13, 2026
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RFC 7292 Appendix C defines iterations as INTEGER (1..MAX).
The loop `for _ in 1..rounds` silently degenerates to a single
hash application for rounds <= 0, producing wrong output without
signalling failure.
Add a rounds < 1 guard to derive_key, derive_key_bmp, and
derive_key_utf8 returning ErrorKind::Value { tag: Tag::Integer }.
Change derive_key and derive_key_bmp return types to der::Result.
Add tests: rounds=1 boundary vectors (verified against OpenSSL
PKCS12KDF), and rounds=0/-1/i32::MIN error cases.
baloo
approved these changes
Apr 13, 2026
baloo
reviewed
Apr 13, 2026
| /// `pass` must be a Unicode (UTF-16BE) byte array in big-endian order without a byte-order mark | ||
| /// and with two terminating zero bytes. | ||
| /// | ||
| /// `rounds` must be ≥ 1 (RFC 7292 Appendix C defines `iterations INTEGER (1..MAX)`). |
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The change makes sense to me (and I already merged it), but I can't actually find the text referred here in the RFC7292. Am I missing something?
This was referenced Apr 16, 2026
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Summary
derive_key,derive_key_bmp, andderive_key_utf8all acceptrounds: i32with no validationfor _ in 1..roundssilently degenerates to a single hash application whenrounds <= 0, producing wrong output with no erroriterations INTEGER (1..MAX)— zero and negative values are out-of-specFix
Add a
rounds < 1guard at the top of each function returningErr(ErrorKind::Value { tag: Tag::Integer }).derive_keyandderive_key_bmpreturn types change fromVec<u8>toder::Result<Vec<u8>>to carry the error.Tests
pkcs12_key_derive_rounds_one_boundary— verifiesrounds=1produces the correct output forEncryptionKeyandMackey types (SHA-256, vectors generated withopenssl kdf … -kdfopt iter:1 … PKCS12KDFand hardcoded)pkcs12_key_derive_zero_rounds_errors— asserts thatrounds=0,rounds=-1, androunds=i32::MINall returnErrBreaking change note
derive_keyandderive_key_bmpare public API. Changing their return type fromVec<u8>toder::Result<Vec<u8>>is a breaking change. Given that the previous behaviour was silently incorrect forrounds <= 0, andpkcs12is still pre-release (0.2.0-pre.0), this seems justified. Happy to discuss alternatives (e.g.u32parameter, or a separate validated wrapper).