/*******************************************************************************
 * Teeny SHA-1
 *
 * The below sha1digest() calculates a SHA-1 hash value for a
 * specified data buffer and generates a hex representation of the
 * result.  This implementation is a re-forming of the SHA-1 code at
 * https://github.com/jinqiangshou/EncryptionLibrary.
 *
 * Copyright (c) 2017 CTrabant
 *
 * License: MIT, see included LICENSE file for details.
 *
 * To use the sha1digest() function either copy it into an existing
 * project source code file or include this file in a project and put
 * the declaration (example below) in the sources files where needed.
 ******************************************************************************/

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

#define print_be(a) \
	printf(#a "= %02x %02x %02x %02x\n", \
		(a >> 0)&0xff,\
		(a >> 8)&0xff,\
		(a >> 16)&0xff,\
		(a >> 24)&0xff);

/* Declaration:
extern int sha1digest(uint8_t *digest, char *hexdigest, const uint8_t *data, size_t databytes);
*/

/*******************************************************************************
 * sha1digest: https://github.com/CTrabant/teeny-sha1
 *
 * Calculate the SHA-1 value for supplied data buffer and generate a
 * text representation in hexadecimal.
 *
 * Based on https://github.com/jinqiangshou/EncryptionLibrary, credit
 * goes to @jinqiangshou, all new bugs are mine.
 *
 * @input:
 *    data      -- data to be hashed
 *    databytes -- bytes in data buffer to be hashed
 *
 * @output:
 *    digest    -- the result, MUST be at least 20 bytes
 *    hexdigest -- the result in hex, MUST be at least 41 bytes
 *
 * At least one of the output buffers must be supplied.  The other, if not 
 * desired, may be set to NULL.
 *
 * @return: 0 on success and non-zero on error.
 ******************************************************************************/
int main(void)
{
#define SHA1ROTATELEFT(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

  uint32_t W[80];
  uint32_t H[] = {0x67452301,
                  0xEFCDAB89,
                  0x98BADCFE,
                  0x10325476,
                  0xC3D2E1F0};
  uint32_t a;
  uint32_t b;
  uint32_t c;
  uint32_t d;
  uint32_t e;
  uint32_t f = 0;
  uint32_t k = 0;

  uint32_t idx;
  uint32_t lidx;
  uint32_t widx;
  uint32_t didx = 0;

  int32_t wcount;
  uint32_t temp;

{

    /* Main loop */
    a = H[0];
    b = H[1];
    c = H[2];
    d = H[3];
    e = H[4];

    for (idx = 0; idx <= 79; idx++)
    {
      if (idx <= 19)
      {
        f = (b & c) | ((~b) & d);
        k = 0x5A827999;
      }
      else if (idx >= 20 && idx <= 39)
      {
        f = b ^ c ^ d;
        k = 0x6ED9EBA1;
      }
      else if (idx >= 40 && idx <= 59)
      {
        f = (b & c) | (b & d) | (c & d);
        k = 0x8F1BBCDC;
      }
      else if (idx >= 60 && idx <= 79)
      {
        f = b ^ c ^ d;
        k = 0xCA62C1D6;
      }
   print_be(f);
      temp = SHA1ROTATELEFT (a, 5) + f + e + k;
      e = d;
      d = c;
      c = SHA1ROTATELEFT (b, 30);
      b = a;
      a = temp;

	printf("Round %d\n",idx);
 
   print_be(a);
   print_be(b);
   print_be(c);
   print_be(d);
   print_be(e);
    }

    H[0] += a;
    H[1] += b;
    H[2] += c;
    H[3] += d;
    H[4] += e;
  }

  return 0;
}  /* End of sha1digest() */