In a publication dated October 2, 2026, Trail of Bits introduced SequenceHash and SequenceMAC, constructions for combining inputs unambiguously without relying on a single hash function.
Trail of Bits introduced SequenceHash and SequenceMAC to hash multiple inputs while avoiding ambiguities that can arise when values are concatenated without delimiters. The constructions are similar to NIST TupleHash, but are not tied to one hash function and do not require bit-level, non-byte-aligned calculations. The publication stresses that their security depends on the underlying function: these constructions cannot make weak functions secure. SequenceMAC accepts keys of 32 bytes or more.
The open specification has joined the Community Cryptography Specification Project (C2SP). The announcement includes initial implementations in Rust, Go, and Python, plus test vectors with intermediate values to help developers debug and verify implementations. Consult the original publication and specification to inspect the details, test the examples, and confirm compatibility with the selected hash function.