sha3

Embeddable, dependency-free, MIT-0 licensed C11 implementation of the SHA-3 cryptographic hash functions, eXtendable Output Functions (XOFs), and Hash-based Message Authentication Code functions (HMAC) defined in FIPS 202, SP 800-185, and the draft KangarooTwelve and TurboSHAKE specification.

Includes AVX-512 acceleration, Doxygen-friendly API documentation, and a full test suite with sanitizers enabled and test vectors from the NIST CSRC "Examples With Intermediate Values" site, the NIST Cryptographic Algorithm Validation Program (CAVP), and the Test Vectors section of the draft KangarooTwelve and TurboSHAKE specification.

The following algorithms are implemented:

• SHA3-224, SHA3-256, SHA3-384, and SHA3-512: SHA-3 cryptographic hash functions, as defined in section 6.1 of FIPS 202.
• SHAKE128 and SHAKE256: XOFs as defined in section 6.2 of FIPS 202.
• HMAC-SHA3-224, HMAC-SHA3-256, HMAC-SHA3-384, HMAC-SHA3-512: HMAC instantiated with SHA-3 hash functions, as specified in section 7 of FIPS 202, RFC 2104, and FIPS 198-1.
• cSHAKE128, cSHAKE128-XOF, cSHAKE256, and cSHAKE256-XOF: Fixed-length and XOF variants of the customizable-SHAKE primitive, as defined in section 3 of SP 800-185.
• KMAC128, KMAC128-XOF, KMAC256 and KMAC256-XOF: Keccak Message Authentication Code (MAC), as defined in section 4 of SP 800-185.
• TupleHash128, TupleHash128-XOF, TupleHash256, and TupleHash256-XOF: Misuse-resistant hash function and XOF for hashing a tuple of byte strings, as defined in section 5 of SP 800-185.
• ParallelHash128, ParallelHash128-XOF, ParallelHash256, and ParallelHash256-XOF: Hash function and XOF, as defined in section 6 of SP 800-185.
• TurboSHAKE128 and TurboSHAKE256: Faster, reduced-round XOFs, as defined in the draft KangarooTwelve and TurboSHAKE specification.
• KangarooTwelve: Faster, reduced-round XOF with a customzation string, as defined in the draft KangarooTwelve and TurboSHAKE specification.

Use make to build a shared library and minimal sample application, make doc to generate HTML-formatted API documentation, and make test to run the test suite.

Examples

Calculate the SHA3-256 hash of a test string and print the result to standard output:

// sha3-256-example: print sha3-256 hash of data to standard output.
#include <stdint.h> // uint8_t
#include <stdio.h> // printf()
#include "hex.h" // hex_write()
#include "sha3.h" // sha3_256()

// test data
static const uint8_t DATA[] = "this is some test data";

int main(void) {
  // hash `DATA` into `buf`
  uint8_t buf[32] = { 0 };
  sha3_256(DATA, sizeof(DATA), buf);

  // print result to stdout
  printf("SHA3-256: ");
  hex_write(stdout, buf, sizeof(buf));
  printf("\n");

  return 0;
}

Calculate the SHAKE128 hash of a test string and print the first 200 bytes to standard output:

//
// shake128-example: hash contents of DATA with SHAKE128 and print first
// 200 bytes of SHAKE128 hash of data to standard output.
//
#include <stdint.h> // uint8_t
#include <stdio.h> // printf()
#include "hex.h" // hex_write()
#include "sha3.h" // shake128()

// test data
static const uint8_t DATA[] = "this is some test data";

int main(void) {
  // hash data
  uint8_t buf[200] = { 0 };
  shake128(DATA, sizeof(DATA), buf, sizeof(buf));

  // print result to stdout
  printf("SHAKE128 (200 bytes): ");
  hex_write(stdout, buf, sizeof(buf));
  printf("\n");

  return 0;
}

TurboSHAKE128 example, using the iterative API:

//
// turboshake128-example: Absorb 4096 bytes of data from /dev/urandom in
// 1024 byte chunks, hash it with TurboShake128, then print 128 bytes of
// result in 32 byte chunks (hex-encoded) to standard output.
// output.
//
#include <stdint.h> // uint8_t
#include <stdio.h> // fopen(), fread(), fclose(), printf()
#include <err.h> // err(), warn()
#include "hex.h" // hex_write()
#include "sha3.h" // turboshake128_*()

int main(void) {
  // init turboshake
  turboshake_t ts;
  turboshake128_init(&ts);

  // open source
  FILE *fh = fopen("/dev/urandom", "rb");
  if (!fh) {
    err(-1, "fopen()");
  }

  {
    // read and absorb
    uint8_t buf[1024] = { 0 };
    for (size_t i = 0; i < 4096/sizeof(buf); i++) {
      // read data
      if (!fread(buf, sizeof(buf), 1, fh)) {
        err(-1, "fread()");
      }

      // absorb
      turboshake128_absorb(&ts, buf, sizeof(buf));
    }
  }

  // close source
  if (!fclose(fh)) {
    warn("fclose()");
  }


  printf("TurboShake128 output:\n");
  {
    // squeeze in 32 byte chunks, write to stdout
    uint8_t buf[32] = { 0 };
    for (size_t ofs = 0; ofs < 128; ofs += sizeof(buf)) {
      turboshake128_squeeze(&ts, buf, sizeof(buf));
      hex_write(stdout, buf, sizeof(buf));
    }
  }
  printf("\n");

  return 0;
}

See the examples/ directory for more.

Usage

To use this library in your application:

1. Copy sha3.h and sha3.c into your source tree.
2. Update your build system to compile sha3.o. See the Makefile for compiler flags.
3. Include sha3.h in your application.

See the top-level Makefile and the examples for recommended compiler flags.

Documentation

Full API documentation is available online here and in the comments of sha3.h. If you have Doxygen installed, you can generate HTML-formatted API documentation by typing make doc.

Tests

Use make test to build and run the test suite.

The test suite checks each component of this implementation for expected answers and is built with several sanitizers supported by both GCC and Clang. The source code for the test suite is embedded at the bottom of sha3.c behind a TEST_SHA3 define.

An additional set of tests for the FIPS 202 hash and XOFs is available in tests/cavp-tests/. These test cases are generated from the Cryptographic Algorithm Validation Program (CAVP) byte test vectors, and are excluded from the main test suite because of their size.

Backends

This library includes several accelerated backends which are selectable at compile time via the BACKEND make argument and define. By default the fastest backend is selected at compile-time.

The available backends are:

• Scalar (BACKEND=1): Default if no faster backend is available.
• AVX-512 (BACKEND=2): AVX-512 acceleration. Selected by default if AVX-512 is supported.
• AVX2 (BACKEND=6): AVX2 acceleration. Currently slower than the scalar backend and not enabled by default.
• Neon (BACKEND=3): ARM Neon acceleration. Currently slower than the scalar backend on ARM CPUs and not enabled by default.

The name of the selected backend is available at run-time via the sha3_backend() function. See the tests/bench/ for examples of the BACKEND make argument and the sha3_backend() function.

Benchmarks

A minimal libcpucycles-based benchmarking tool is available in tests/bench/. The bench tool measures the median cycles per byte (cpb) for a variety of message lengths, then prints a table of results to standard output in CSV format.

bench results from several of my systems are shown in the tables below.

Lenovo ThinkPad X1 Carbon, 6th Gen (i7-1185G7, AVX-512 Backend)

Raspberry Pi 5 (Cortex-A76, Scalar Backend)

Odroid N2L (Cortex-A73, Scalar Backend)

References

• FIPS 202 - SHA-3 Standard: Permutation-Based Hash and Extendable-Output Functions
• NIST SP 800-185 - SHA-3 Derived Functions: cSHAKE, KMAC, TupleHash, and ParallelHash
• FIPS 198-1 - The Keyed-Hash Message Authentication Code (HMAC)
• NIST CSRC: Cryptographic Standards and Guidelines: Examples with Intermediate Values
• NIST CSRC: Cryptographic Algorithm Validation Program (CAVP)
• TurboSHAKE (PDF)
• KangarooTwelve and TurboSHAKE

License

MIT No Attribution (MIT-0)

Copyright 2023, 2024 Paul Duncan

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.