lib/halfmd4.c

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