3 * The compression function of the sha256 hash function.
6 /* nettle, low-level cryptographics library
8 * Copyright (C) 2001, 2010 Niels Möller
10 * The nettle library is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU Lesser General Public License as published by
12 * the Free Software Foundation; either version 2.1 of the License, or (at your
13 * option) any later version.
15 * The nettle library is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
17 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
18 * License for more details.
20 * You should have received a copy of the GNU Lesser General Public License
21 * along with the nettle library; see the file COPYING.LIB. If not, write to
22 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
38 /* A block, treated as a sequence of 32-bit words. */
39 #define SHA256_DATA_LENGTH 16
41 #define ROTR(n,x) ((x)>>(n) | ((x)<<(32-(n))))
42 #define SHR(n,x) ((x)>>(n))
44 /* The SHA256 functions. The Choice function is the same as the SHA1
45 function f1, and the majority function is the same as the SHA1 f3
46 function. They can be optimized to save one boolean operation each
47 - thanks to Rich Schroeppel, rcs@cs.arizona.edu for discovering
50 /* #define Choice(x,y,z) ( ( (x) & (y) ) | ( ~(x) & (z) ) ) */
51 #define Choice(x,y,z) ( (z) ^ ( (x) & ( (y) ^ (z) ) ) )
52 /* #define Majority(x,y,z) ( ((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)) ) */
53 #define Majority(x,y,z) ( ((x) & (y)) ^ ((z) & ((x) ^ (y))) )
55 #define S0(x) (ROTR(2,(x)) ^ ROTR(13,(x)) ^ ROTR(22,(x)))
56 #define S1(x) (ROTR(6,(x)) ^ ROTR(11,(x)) ^ ROTR(25,(x)))
58 #define s0(x) (ROTR(7,(x)) ^ ROTR(18,(x)) ^ SHR(3,(x)))
59 #define s1(x) (ROTR(17,(x)) ^ ROTR(19,(x)) ^ SHR(10,(x)))
61 /* The initial expanding function. The hash function is defined over an
62 64-word expanded input array W, where the first 16 are copies of the input
63 data, and the remaining 64 are defined by
65 W[ t ] = s1(W[t-2]) + W[t-7] + s0(W[i-15]) + W[i-16]
67 This implementation generates these values on the fly in a circular
68 buffer - thanks to Colin Plumb, colin@nyx10.cs.du.edu for this
73 ( W[(i) & 15 ] += (s1(W[((i)-2) & 15]) + W[((i)-7) & 15] + s0(W[((i)-15) & 15])) )
75 /* The prototype SHA sub-round. The fundamental sub-round is:
77 T1 = h + S1(e) + Choice(e,f,g) + K[t] + W[t]
78 T2 = S0(a) + Majority(a,b,c)
88 but this is implemented by unrolling the loop 8 times and renaming
90 ( h, a, b, c, d, e, f, g ) = ( a, b, c, d, e, f, g, h ) each
93 /* It's crucial that DATA is only used once, as that argument will
94 * have side effects. */
95 #define ROUND(a,b,c,d,e,f,g,h,k,data) do { \
96 uint32_t T = h + S1(e) + Choice(e,f,g) + k + data; \
98 h = T + S0(a) + Majority(a,b,c); \
102 _nettle_sha256_compress(uint32_t *state, const uint8_t *input, const uint32_t *k)
104 uint32_t data[SHA256_DATA_LENGTH];
105 uint32_t A, B, C, D, E, F, G, H; /* Local vars */
109 for (i = 0; i < SHA256_DATA_LENGTH; i++, input+= 4)
111 data[i] = READ_UINT32(input);
114 /* Set up first buffer and local data buffer */
125 /* First 16 subrounds that act on the original data */
127 for (i = 0, d = data; i<16; i+=8, k += 8, d+= 8)
129 ROUND(A, B, C, D, E, F, G, H, k[0], d[0]);
130 ROUND(H, A, B, C, D, E, F, G, k[1], d[1]);
131 ROUND(G, H, A, B, C, D, E, F, k[2], d[2]);
132 ROUND(F, G, H, A, B, C, D, E, k[3], d[3]);
133 ROUND(E, F, G, H, A, B, C, D, k[4], d[4]);
134 ROUND(D, E, F, G, H, A, B, C, k[5], d[5]);
135 ROUND(C, D, E, F, G, H, A, B, k[6], d[6]);
136 ROUND(B, C, D, E, F, G, H, A, k[7], d[7]);
139 for (; i<64; i += 16, k+= 16)
141 ROUND(A, B, C, D, E, F, G, H, k[ 0], EXPAND(data, 0));
142 ROUND(H, A, B, C, D, E, F, G, k[ 1], EXPAND(data, 1));
143 ROUND(G, H, A, B, C, D, E, F, k[ 2], EXPAND(data, 2));
144 ROUND(F, G, H, A, B, C, D, E, k[ 3], EXPAND(data, 3));
145 ROUND(E, F, G, H, A, B, C, D, k[ 4], EXPAND(data, 4));
146 ROUND(D, E, F, G, H, A, B, C, k[ 5], EXPAND(data, 5));
147 ROUND(C, D, E, F, G, H, A, B, k[ 6], EXPAND(data, 6));
148 ROUND(B, C, D, E, F, G, H, A, k[ 7], EXPAND(data, 7));
149 ROUND(A, B, C, D, E, F, G, H, k[ 8], EXPAND(data, 8));
150 ROUND(H, A, B, C, D, E, F, G, k[ 9], EXPAND(data, 9));
151 ROUND(G, H, A, B, C, D, E, F, k[10], EXPAND(data, 10));
152 ROUND(F, G, H, A, B, C, D, E, k[11], EXPAND(data, 11));
153 ROUND(E, F, G, H, A, B, C, D, k[12], EXPAND(data, 12));
154 ROUND(D, E, F, G, H, A, B, C, k[13], EXPAND(data, 13));
155 ROUND(C, D, E, F, G, H, A, B, k[14], EXPAND(data, 14));
156 ROUND(B, C, D, E, F, G, H, A, k[15], EXPAND(data, 15));