blake2b

Pure Elm implementation of the BLAKE2b cryptographic hash function (RFC 7693).

No kernel code, no ports, no JS FFI — just Elm.

Install

elm install elm-cardano/blake2b

Development

pnpm install
pnpm test          # run tests
pnpm review        # run elm-review
pnpm format:check  # check formatting
pnpm format        # auto-format

Usage

import Blake2b
import Bytes exposing (Bytes)
import Bytes.Encode

message : Bytes
message =
    Bytes.Encode.encode (Bytes.Encode.string "hello")

-- 512-bit hash (64 bytes), the default for BLAKE2b
digest : Bytes
digest =
    Blake2b.hash512 message

-- 256-bit hash (32 bytes)
digest256 : Bytes
digest256 =
    Blake2b.hash256 message

-- Custom digest length and keyed hashing
keyed : Bytes
keyed =
    Blake2b.hash
        { digestLength = 48
        , key = Bytes.Encode.encode (Bytes.Encode.string "secret")
        , data = message
        }

API

• hash512 : Bytes -> Bytes — 512-bit (64-byte) hash
• hash256 : Bytes -> Bytes — 256-bit (32-byte) hash
• hash224 : Bytes -> Bytes — 224-bit (28-byte) hash
• hash : { digestLength : Int, key : Bytes, data : Bytes } -> Bytes — configurable digest length (1-64) and optional key (0-64 bytes)

Performance

64-bit arithmetic is emulated using pairs of 32-bit integers. All intermediate values in the compression function are let bindings on raw Int pairs, which compile to plain JS variables with zero allocation. This keeps garbage collection pressure low and makes the implementation practical for real use.

For details on the optimization journey, see docs/IMPLEMENTATION.md. Benchmarking infrastructure lives in the bench/ folder.

Correctness

Tested against:

• RFC 7693 test vectors (BLAKE2b-512(""), BLAKE2b-512("abc"))
• RFC 7693 Appendix E self-test (all digest lengths, keyed and unkeyed, input lengths 0-255)
• BLAKE2 KAT vectors (keyed hashing at boundary lengths)

License

BSD-3-Clause