lib/halfmd4.c

   1 #include <linux/compiler.h>
   2 #include <linux/export.h>
   3 #include <linux/cryptohash.h>
   4 #include <linux/bitops.h>
   5
   6 /* F, G and H are basic MD4 functions: selection, majority, parity */
   7 #define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
   8 #define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
   9 #define H(x, y, z) ((x) ^ (y) ^ (z))
  10
  11 /*
  12  * The generic round function.  The application is so specific that
  13  * we don't bother protecting all the arguments with parens, as is generally
  14  * good macro practice, in favor of extra legibility.
  15  * Rotation is separate from addition to prevent recomputation
  16  */
  17 #define ROUND(f, a, b, c, d, x, s)      \
  18         (a += f(b, c, d) + x, a = rol32(a, s))
  19 #define K1 0
  20 #define K2 013240474631UL
  21 #define K3 015666365641UL
  22
  23 /*
  24  * Basic cut-down MD4 transform.  Returns only 32 bits of result.
  25  */
  26 __u32 half_md4_transform(__u32 buf[4], __u32 const in[8])
  27 {
  28         __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
  29
  30         /* Round 1 */
  31         ROUND(F, a, b, c, d, in[0] + K1,  3);
  32         ROUND(F, d, a, b, c, in[1] + K1,  7);
  33         ROUND(F, c, d, a, b, in[2] + K1, 11);
  34         ROUND(F, b, c, d, a, in[3] + K1, 19);
  35         ROUND(F, a, b, c, d, in[4] + K1,  3);
  36         ROUND(F, d, a, b, c, in[5] + K1,  7);
  37         ROUND(F, c, d, a, b, in[6] + K1, 11);
  38         ROUND(F, b, c, d, a, in[7] + K1, 19);
  39
  40         /* Round 2 */
  41         ROUND(G, a, b, c, d, in[1] + K2,  3);
  42         ROUND(G, d, a, b, c, in[3] + K2,  5);
  43         ROUND(G, c, d, a, b, in[5] + K2,  9);
  44         ROUND(G, b, c, d, a, in[7] + K2, 13);
  45         ROUND(G, a, b, c, d, in[0] + K2,  3);
  46         ROUND(G, d, a, b, c, in[2] + K2,  5);
  47         ROUND(G, c, d, a, b, in[4] + K2,  9);
  48         ROUND(G, b, c, d, a, in[6] + K2, 13);
  49
  50         /* Round 3 */
  51         ROUND(H, a, b, c, d, in[3] + K3,  3);
  52         ROUND(H, d, a, b, c, in[7] + K3,  9);
  53         ROUND(H, c, d, a, b, in[2] + K3, 11);
  54         ROUND(H, b, c, d, a, in[6] + K3, 15);
  55         ROUND(H, a, b, c, d, in[1] + K3,  3);
  56         ROUND(H, d, a, b, c, in[5] + K3,  9);
  57         ROUND(H, c, d, a, b, in[0] + K3, 11);
  58         ROUND(H, b, c, d, a, in[4] + K3, 15);
  59
  60         buf[0] += a;
  61         buf[1] += b;
  62         buf[2] += c;
  63         buf[3] += d;
  64
  65         return buf[1]; /* "most hashed" word */
  66 }
  67 EXPORT_SYMBOL(half_md4_transform);