c-sha1

SHA1 library for C

• Supports one call calculation and streaming protocol
• Requires C99 or newer
• Implementation verified against NIST CAVP test vectors

Usage

To use the library add sha1.h and sha1.c to your project.
Example:

#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <stdlib.h>

#include "sha1.h"

static void print_hash(const uint8_t hash[SHA1_HASH_LEN])
{
  char *hash_str = sha1_to_str(hash);
  if (hash_str != NULL)
  {
    puts(hash_str);
    free(hash_str);
  }
}

static void print_hash_without_allocation(const uint8_t hash[SHA1_HASH_LEN])
{
  char hash_str[SHA1_STR_LEN];
  sha1_to_str_buffer(hash, hash_str);
  puts(hash_str);
}

int main(void)
{
  const char *msg = "The quick brown fox jumps over the lazy dog.";

  uint8_t hash[SHA1_HASH_LEN];

  // Calculate hash in one call
  sha1((uint8_t*)msg, strlen(msg), hash);
  print_hash(hash);

  // Calculate hash with streaming protocol
  const char *msg_part_one = "The quick brown fox ";
  const char *msg_part_two = "jumps over the lazy dog.";

  sha1_ctx ctx;
  sha1_init(&ctx);
  sha1_process(&ctx, (uint8_t*)msg_part_one, strlen(msg_part_one));
  sha1_process(&ctx, (uint8_t*)msg_part_two, strlen(msg_part_two));
  sha1_finalize(&ctx, hash);
  print_hash_without_allocation(hash);

  return 0;
}

// Output:
//  408d94384216f890ff7a0c3528e8bed1e0b01621
//  408d94384216f890ff7a0c3528e8bed1e0b01621

API

The string returned from sha1_to_str must be freed by the caller.
Use sha1_to_str_buffer to create a string without allocation.

extern void sha1(const uint8_t *data, size_t size, uint8_t result[static SHA1_HASH_LEN]);
extern void sha1_init(sha1_ctx *ctx);
extern void sha1_process(sha1_ctx *ctx, const uint8_t *data, size_t size);
extern void sha1_finalize(sha1_ctx *ctx, uint8_t result[static SHA1_HASH_LEN]);
extern char* sha1_to_str(const uint8_t hash[static SHA1_HASH_LEN]);
extern void sha1_to_str_buffer(const uint8_t hash[static SHA1_HASH_LEN], char dst[static SHA1_STR_LEN]);

Test

The tests are run by calling make.

$ make
SHA1 short...OK
SHA1 long....OK