sha-stuff.c

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>


#define SHA1_BLOCK 64


int main(int argc, char *argv[])
{
  int a, b, c, d, e;
  int h0, h1, h2, h3, h4;
  int i;
  int file_handle;
  unsigned char *sha_data;
  int *w;
  int got;


  printf("Hello, world!\n");

  if (argc < 2)
  {
    fprintf(stderr, "Wrong number of arguments.\n");
    return 1;
  }

  sha_data = (unsigned char *)malloc(SHA1_BLOCK);

  if (sha_data == NULL)
  {
    fprintf(stderr, "Failed to allocate memory for SHA data.\n");
    return 1;
  }

  file_handle = open(argv[1], O_RDONLY);

  if (file_handle < 0)
  {
    fprintf(stderr, "Failed to open file: %s\n", strerror(errno));
    return 1;
  }

  if (read(file_handle, sha_data, SHA1_BLOCK) != SHA1_BLOCK)
  {
    fprintf(stderr, "Could not read %dB from file: %s\n", SHA1_BLOCK, strerror(errno));
    return 1;
  }

  close(file_handle);

  w = (int *)malloc(80 * sizeof(int));

  if (w == NULL)
  {
    fprintf(stderr, "Failed to allocate memory for SHA words.\n");
    return 1;
  }

  for (i = 0; i < 16; i++)
  {
    /* Convert big-endian to native */
    w[i] = sha_data[i * 4 + 3] * 16777216 + \
           sha_data[i * 4 + 2] * 65536 + \
           sha_data[i * 4 + 1] * 256 + \
           sha_data[i * 4];
  }

  for (i = 16; i < 80; i++)
  {
    w[i] = w[i-3] ^ w[i-8] ^ w[i-14] ^ w[i-16]; /*TODO left rotate 1 whole thing*/
  }

  for (i = 0; i < 80; i++)
  {
    printf("w[%02d] = 0x%08x", i, w[i]);
    ((i + 1) % 4) ? printf("  ") : printf("\n");
  }

  return 0;
}