Module hash 

Available on crate features hash-blake3 or hash-sha2 only.

Cryptographic hash functions.

Three algorithms ship in 0.4.0, exposed through a consistent free-function API plus matching streaming hashers for inputs that don’t fit in memory:

Algorithm	One-shot	Streaming	Output	Feature
BLAKE3	blake3()	Blake3Hasher	32 B	hash-blake3
BLAKE3 XOF	blake3_long()	Blake3Hasher	N B	hash-blake3
SHA-256	sha256()	Sha256Hasher	32 B	hash-sha2
SHA-512	sha512()	Sha512Hasher	64 B	hash-sha2

Choosing a hash

Pick BLAKE3 unless you have a reason not to. It is the fastest cryptographic hash on every modern platform — typically 4–10× faster than SHA-256 on x86_64 with AVX2, and faster still on the wide vector units of Apple Silicon. It is also tree-structured and SIMD-friendly, so very large inputs hash at near-memcpy bandwidth.

Pick SHA-256 when you need ecosystem interop — TLS, JWT, Bitcoin, certificate fingerprints, any spec that names SHA-256 explicitly.

Pick SHA-512 when interop demands the wider output (some certificate authorities, some old protocols) or when running on a 64-bit machine where SHA-512 happens to be faster than SHA-256 (it processes 64-bit words natively).

No-key, no-MAC

These functions hash data only. For keyed hashing (BLAKE3 keyed mode, HMAC-SHA2), see the mac module — that’s the Phase 0.5.0 surface and is the right home for authentication-tag semantics. Using a raw hash function as a MAC is a security mistake; we do not expose Hash::with_key here for that reason.

Example

use crypt_io::hash;

let digest = hash::blake3(b"the quick brown fox");
assert_eq!(digest.len(), 32);

With a streaming hasher:

use crypt_io::hash::Blake3Hasher;

let mut h = Blake3Hasher::new();
h.update(b"first chunk");
h.update(b" second chunk");
let digest = h.finalize();
assert_eq!(digest.len(), 32);

Structs

Blake3Hasherhash-blake3

Streaming BLAKE3 hasher for inputs that don’t fit in memory or arrive in chunks.

Sha256Hasherhash-sha2

Streaming SHA-256 hasher for inputs that don’t fit in memory.

Sha512Hasherhash-sha2

Streaming SHA-512 hasher for inputs that don’t fit in memory.

Constants

BLAKE3_OUTPUT_LENhash-blake3

Length of a BLAKE3 digest, in bytes. Equal to 32.

SHA256_OUTPUT_LENhash-sha2

Length of a SHA-256 digest, in bytes. Equal to 32.

SHA512_OUTPUT_LENhash-sha2

Length of a SHA-512 digest, in bytes. Equal to 64.

Functions

blake3hash-blake3

Compute a 32-byte BLAKE3 digest of data.

blake3_longhash-blake3

Compute a BLAKE3 digest of arbitrary length via the extendable-output function (XOF) mode.

sha256hash-sha2

Compute a 32-byte SHA-256 digest of data.

sha512hash-sha2

Compute a 64-byte SHA-512 digest of data.