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1 | /* |
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2 | * SHA core transform algorithm, used here solely as a `stirring' |
3 | * function for the PuTTY random number pool. Implemented directly |
4 | * from the specification by Simon Tatham. |
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5 | */ |
6 | |
7 | #include "ssh.h" |
8 | |
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9 | #define rol(x,y) ( ((x) << (y)) | (((word32)x) >> (32-y)) ) |
10 | |
11 | void SHATransform(word32 *digest, word32 *block) { |
12 | word32 w[80]; |
13 | word32 a,b,c,d,e; |
14 | int t; |
15 | |
16 | for (t = 0; t < 16; t++) |
17 | w[t] = block[t]; |
18 | |
19 | for (t = 16; t < 80; t++) { |
20 | word32 tmp = w[t-3] ^ w[t-8] ^ w[t-14] ^ w[t-16]; |
21 | w[t] = rol(tmp, 1); |
22 | } |
23 | |
24 | a = digest[0]; |
25 | b = digest[1]; |
26 | c = digest[2]; |
27 | d = digest[3]; |
28 | e = digest[4]; |
29 | |
30 | for (t = 0; t < 20; t++) { |
31 | word32 tmp = rol(a, 5) + ( (b&c) | (d&~b) ) + e + w[t] + 0x5a827999; |
32 | e = d; d = c; c = rol(b, 30); b = a; a = tmp; |
33 | } |
34 | for (t = 20; t < 40; t++) { |
35 | word32 tmp = rol(a, 5) + (b^c^d) + e + w[t] + 0x6ed9eba1; |
36 | e = d; d = c; c = rol(b, 30); b = a; a = tmp; |
37 | } |
38 | for (t = 40; t < 60; t++) { |
39 | word32 tmp = rol(a, 5) + ( (b&c) | (b&d) | (c&d) ) + e + w[t] + 0x8f1bbcdc; |
40 | e = d; d = c; c = rol(b, 30); b = a; a = tmp; |
41 | } |
42 | for (t = 60; t < 80; t++) { |
43 | word32 tmp = rol(a, 5) + (b^c^d) + e + w[t] + 0xca62c1d6; |
44 | e = d; d = c; c = rol(b, 30); b = a; a = tmp; |
45 | } |
46 | |
47 | digest[0] += a; |
48 | digest[1] += b; |
49 | digest[2] += c; |
50 | digest[3] += d; |
51 | digest[4] += e; |
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52 | } |