linux/lib/halfmd4.c
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   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}
  66EXPORT_SYMBOL(half_md4_transform);
  67
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