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SHA-3 / SHAKE256

Algorithm​

SHA-3 uses the Keccak-f[1600] permutation in sponge mode. It is structurally different from SHA-2, which helps when SHA-2 agility is a concern. SHAKE256 is an XOF: you pick how many output bytes you need (within safe bounds enforced by the crate).

Purpose​

Keccak sponge-based digests (FIPS 202): SHA3-256/384/512 and extendable SHAKE256.

Rust API​

  • Crate: noxtls-crypto
  • Module path (conceptual): noxtls_crypto::hash
  • Primary symbols:
    • noxtls_sha3_256
    • noxtls_sha3_384
    • noxtls_sha3_512
    • noxtls_shake256

Functions and types:

  • noxtls_sha3_256 / noxtls_sha3_384 / noxtls_sha3_512 — Fixed-length one-shot digests.
  • noxtls_shake256(data, output_len) -> Vec<u8> - Parameters: data is input bytes and output_len is requested output length in bytes. Behavior: computes SHAKE256 extendable-output function output. Returns: Vec<u8> of exactly output_len bytes.

Feature flags and policy​

Default.

Examples​

use noxtls_crypto::{noxtls_sha3_256, noxtls_shake256};

let d = noxtls_sha3_256(b"abc");
assert_eq!(d.len(), 32);

let xof = noxtls_shake256(b"derive-me", 64);
assert_eq!(xof.len(), 64);

Security and compatibility​

Choose output length for SHAKE256 explicitly; domain-separate different uses with distinct info or prefixes.