C11 SHA-3

This weekend I put together a C11 implementation of the following SHA-3 algorithms from FIPS 202, SP 800-185, and the draft KangarooTwelve and TurboSHAKE specification:

• SHA3-224, SHA3-256, SHA3-384, and SHA3-512
• SHAKE128 and SHAKE256
• HMAC-SHA3-224, HMAC-SHA3-256, HMAC-SHA3-384, and HMAC-SHA3-512
• cSHAKE128, cSHAKE128-XOF, cSHAKE256, and cSHAKE256-XOF
• KMAC128, KMAC128-XOF, KMAC256, and KMAC256-XOF
• TupleHash128, TupleHash128-XOF, TupleHash256, and TupleHash256-XOF
• ParallelHash128, ParallelHash128-XOF, ParallelHash256, and ParallelHash256-XOF
• TurboSHAKE128 and TurboSHAKE256
• KangarooTwelve

Git Repository, API Documentation

Features

• MIT-0 licensed
• Standard C11 with no external dependencies.
• No allocations.
• Easy to embed: drop sha3.h and sha3.c into your application.
• Full Doxygen API documentation (available online here).
• Full test suite based on test vectors from the NIST Cryptographic Algorithm Validation Program (CAVP), the NIST CSRC Examples with Intermediate Values page. and the Test Vectors section of the draft KangarooTwelve and TurboSHAKE specification.

Example

// example.c: print hex-encode sha3-256 hash of each command-line argument
//
// build:
//   cc -o example -std=c11 -O3 -W -Wall -Wextra -Werror -pedantic -march=native -mtune=native example.c sha3.c
#include <stdint.h> // uint8_t
#include <stdio.h> // printf()
#include <string.h> // strlen()
#include "sha3.h" // sha3_256()

// print hex-encoded buffer to stdout.
static void print_hex(const uint8_t * const buf, const size_t len) {
  for (size_t i = 0; i < len; i++) {
    printf("%02x", buf[i]);
  }
}

int main(int argc, char *argv[]) {
  // loop over command-line arguments
  for (int i = 1; i < argc; i++) {
    // hash argument
    uint8_t buf[32] = { 0 };
    sha3_256((uint8_t*) argv[i], strlen(argv[i]), buf);

    // print argument and hex-encoded hash
    printf("\"%s\",", argv[i]);
    print_hex(buf, sizeof(buf));
    fputs("\n", stdout);
  }

  // return success
  return 0;
}

Output:

> ./example asdf foo bar
"asdf",dd2781f4c51bccdbe23e4d398b8a82261f585c278dbb4b84989fea70e76723a9
"foo",76d3bc41c9f588f7fcd0d5bf4718f8f84b1c41b20882703100b9eb9413807c01
"bar",cceefd7e0545bcf8b6d19f3b5750c8a3ee8350418877bc6fb12e32de28137355

Update (2023-09-07): Released v0.2 with TurboSHAKE128, TurboSHAKE256, KangarooTwelve, and an examples/ directory.

Update (2023-09-18): Released v0.3 with AVX-512 support (~3x faster) and miscellaneous small fixes.

Update (2023-10-15): Released v0.4 with lots of documentation improvements.

Update (2023-10-19): Released v0.5 with more documentation improvements and additional examples. added online API documentation.

Update (2024-03-02): Released v0.6 with speed improvements, simplified SHAKE API, and documentation updates. Added CAVP test vectors.