Root/lib/halfmd4.c

1#include <linux/kernel.h>
2#include <linux/module.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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