Suite B

PQC Suite B: Faster Signatures with BLAKE3

Post-quantum signature schemes spend a substantial fraction of their runtime on hashing. ML-DSA uses SHAKE128 and SHAKE256; SLH-DSA offers variants built on SHA-256 or SHAKE. In both cases, the choice of hash function has a measurable impact on signing and verification performance.

PQC Suite-B [101] is a proposal, co-authored by JP Aumasson, Conor Deegan, Alex Pruden, and Zooko Wilcox-O’Hearn, to replace the internal hash functions in ML-DSA and SLH-DSA with BLAKE3, the fastest widely deployed cryptographic hash. The resulting schemes are called ML-DSA-B and SLH-DSA-B. BLAKE3 serves as a drop-in replacement for every hashing mode these schemes use.

Experimental benchmarks modifying RustCrypto’s implementations show meaningful speed-ups. For ML-DSA-B, message pre-hashing is up to 60 times faster, signing up to 20% faster, and verification up to 30% faster.

For SLH-DSA-B, the picture is more nuanced. SHAKE is consistently the slowest option, 4 to 7 times slower due to its higher per-bit hashing cost. BLAKE3 and SHA-2 perform in a similar range, with the winner determined by hardware: x86 platforms favor BLAKE3 (SIMD parallelism), while Apple silicon favors SHA-2 (dedicated hardware acceleration).

These results matter for blockchains. Every signature operation in a node’s critical path, whether block validation, transaction relay, or consensus, is performed at scale and under latency pressure. A 20 to 30 percent verification improvement compounds across thousands of transactions per block. Importantly, PQC Suite-B does not change signature, public key, or private key sizes. It delivers a pure performance improvement with no trade-off against the size constraints that are already the central engineering challenge for post-quantum blockchains.

Signature Time for 1MB Messages (Lower = Better)