/*
   * SHA transform algorithm, originally taken from code written by
   * Peter Gutmann, and placed in the public domain.
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/cryptohash.h>
  
  /* The SHA f()-functions.  */
  
  #define f1(x,y,z)   (z ^ (x & (y ^ z)))		/* x ? y : z */
  #define f2(x,y,z)   (x ^ y ^ z)			/* XOR */
  #define f3(x,y,z)   ((x & y) + (z & (x ^ y)))	/* majority */
  
  /* The SHA Mysterious Constants */
  
  #define K1  0x5A827999L			/* Rounds  0-19: sqrt(2) * 2^30 */
  #define K2  0x6ED9EBA1L			/* Rounds 20-39: sqrt(3) * 2^30 */
  #define K3  0x8F1BBCDCL			/* Rounds 40-59: sqrt(5) * 2^30 */
  #define K4  0xCA62C1D6L			/* Rounds 60-79: sqrt(10) * 2^30 */

  /**
   * sha_transform - single block SHA1 transform

   *
   * @digest: 160 bit digest to update
   * @data:   512 bits of data to hash
   * @W:      80 words of workspace (see note)
   *
   * This function generates a SHA1 digest for a single 512-bit block.
   * Be warned, it does not handle padding and message digest, do not
   * confuse it with the full FIPS 180-1 digest algorithm for variable
   * length messages.
   *
   * Note: If the hash is security sensitive, the caller should be sure
   * to clear the workspace. This is left to the caller to avoid
   * unnecessary clears between chained hashing operations.
   */
  void sha_transform(__u32 *digest, const char *in, __u32 *W)
  {
  	__u32 a, b, c, d, e, t, i;
  
  	for (i = 0; i < 16; i++)

  		W[i] = be32_to_cpu(((const __be32 *)in)[i]);

  
  	for (i = 0; i < 64; i++)
  		W[i+16] = rol32(W[i+13] ^ W[i+8] ^ W[i+2] ^ W[i], 1);
  
  	a = digest[0];
  	b = digest[1];
  	c = digest[2];
  	d = digest[3];
  	e = digest[4];
  
  	for (i = 0; i < 20; i++) {
  		t = f1(b, c, d) + K1 + rol32(a, 5) + e + W[i];
  		e = d; d = c; c = rol32(b, 30); b = a; a = t;
  	}
  
  	for (; i < 40; i ++) {
  		t = f2(b, c, d) + K2 + rol32(a, 5) + e + W[i];
  		e = d; d = c; c = rol32(b, 30); b = a; a = t;
  	}
  
  	for (; i < 60; i ++) {
  		t = f3(b, c, d) + K3 + rol32(a, 5) + e + W[i];
  		e = d; d = c; c = rol32(b, 30); b = a; a = t;
  	}
  
  	for (; i < 80; i ++) {
  		t = f2(b, c, d) + K4 + rol32(a, 5) + e + W[i];
  		e = d; d = c; c = rol32(b, 30); b = a; a = t;
  	}
  
  	digest[0] += a;
  	digest[1] += b;
  	digest[2] += c;
  	digest[3] += d;
  	digest[4] += e;
  }
  EXPORT_SYMBOL(sha_transform);

  /**
   * sha_init - initialize the vectors for a SHA1 digest

   * @buf: vector to initialize
   */
  void sha_init(__u32 *buf)
  {
  	buf[0] = 0x67452301;
  	buf[1] = 0xefcdab89;
  	buf[2] = 0x98badcfe;
  	buf[3] = 0x10325476;
  	buf[4] = 0xc3d2e1f0;
  }