1/* Functions to compute SHA256 message digest of files or memory blocks.
2 according to the definition of SHA256 in FIPS 180-2.
3 Copyright (C) 2007-2022 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20
21#ifdef HAVE_CONFIG_H
22# include <config.h>
23#endif
24
25#include <endian.h>
26#include <stdlib.h>
27#include <string.h>
28#include <stdint.h>
29#include <sys/types.h>
30
31#include "sha256.h"
32
33#if __BYTE_ORDER == __LITTLE_ENDIAN
34# ifdef _LIBC
35# include <byteswap.h>
36# define SWAP(n) bswap_32 (n)
37# define SWAP64(n) bswap_64 (n)
38# else
39# define SWAP(n) \
40 (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
41# define SWAP64(n) \
42 (((n) << 56) \
43 | (((n) & 0xff00) << 40) \
44 | (((n) & 0xff0000) << 24) \
45 | (((n) & 0xff000000) << 8) \
46 | (((n) >> 8) & 0xff000000) \
47 | (((n) >> 24) & 0xff0000) \
48 | (((n) >> 40) & 0xff00) \
49 | ((n) >> 56))
50# endif
51#else
52# define SWAP(n) (n)
53# define SWAP64(n) (n)
54#endif
55
56
57/* This array contains the bytes used to pad the buffer to the next
58 64-byte boundary. (FIPS 180-2:5.1.1) */
59static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ... */ };
60
61
62/* Constants for SHA256 from FIPS 180-2:4.2.2. */
63static const uint32_t K[64] =
64 {
65 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
66 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
67 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
68 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
69 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
70 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
71 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
72 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
73 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
74 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
75 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
76 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
77 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
78 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
79 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
80 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
81 };
82
83void __sha256_process_block (const void *, size_t, struct sha256_ctx *);
84
85/* Initialize structure containing state of computation.
86 (FIPS 180-2:5.3.2) */
87void
88__sha256_init_ctx (struct sha256_ctx *ctx)
89{
90 ctx->H[0] = 0x6a09e667;
91 ctx->H[1] = 0xbb67ae85;
92 ctx->H[2] = 0x3c6ef372;
93 ctx->H[3] = 0xa54ff53a;
94 ctx->H[4] = 0x510e527f;
95 ctx->H[5] = 0x9b05688c;
96 ctx->H[6] = 0x1f83d9ab;
97 ctx->H[7] = 0x5be0cd19;
98
99 ctx->total64 = 0;
100 ctx->buflen = 0;
101}
102
103
104/* Process the remaining bytes in the internal buffer and the usual
105 prolog according to the standard and write the result to RESBUF.
106
107 IMPORTANT: On some systems it is required that RESBUF is correctly
108 aligned for a 32 bits value. */
109void *
110__sha256_finish_ctx (struct sha256_ctx *ctx, void *resbuf)
111{
112 /* Take yet unprocessed bytes into account. */
113 uint32_t bytes = ctx->buflen;
114 size_t pad;
115
116 /* Now count remaining bytes. */
117 ctx->total64 += bytes;
118
119 pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
120 memcpy (&ctx->buffer[bytes], fillbuf, pad);
121
122 /* Put the 64-bit file length in *bits* at the end of the buffer. */
123#if _STRING_ARCH_unaligned
124 ctx->buffer64[(bytes + pad) / 8] = SWAP64 (ctx->total64 << 3);
125#else
126 ctx->buffer32[(bytes + pad + 4) / 4] = SWAP (ctx->total[TOTAL64_low] << 3);
127 ctx->buffer32[(bytes + pad) / 4] = SWAP ((ctx->total[TOTAL64_high] << 3)
128 | (ctx->total[TOTAL64_low] >> 29));
129#endif
130
131 /* Process last bytes. */
132 __sha256_process_block (ctx->buffer, bytes + pad + 8, ctx);
133
134 /* Put result from CTX in first 32 bytes following RESBUF. */
135 for (unsigned int i = 0; i < 8; ++i)
136 ((uint32_t *) resbuf)[i] = SWAP (ctx->H[i]);
137
138 return resbuf;
139}
140
141
142void
143__sha256_process_bytes (const void *buffer, size_t len, struct sha256_ctx *ctx)
144{
145 /* When we already have some bits in our internal buffer concatenate
146 both inputs first. */
147 if (ctx->buflen != 0)
148 {
149 size_t left_over = ctx->buflen;
150 size_t add = 128 - left_over > len ? len : 128 - left_over;
151
152 memcpy (&ctx->buffer[left_over], buffer, add);
153 ctx->buflen += add;
154
155 if (ctx->buflen > 64)
156 {
157 __sha256_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
158
159 ctx->buflen &= 63;
160 /* The regions in the following copy operation cannot overlap. */
161 memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
162 ctx->buflen);
163 }
164
165 buffer = (const char *) buffer + add;
166 len -= add;
167 }
168
169 /* Process available complete blocks. */
170 if (len >= 64)
171 {
172#if !_STRING_ARCH_unaligned
173/* To check alignment gcc has an appropriate operator. Other
174 compilers don't. */
175# if __GNUC__ >= 2
176# define UNALIGNED_P(p) (((uintptr_t) p) % __alignof__ (uint32_t) != 0)
177# else
178# define UNALIGNED_P(p) (((uintptr_t) p) % sizeof (uint32_t) != 0)
179# endif
180 if (UNALIGNED_P (buffer))
181 while (len > 64)
182 {
183 __sha256_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
184 buffer = (const char *) buffer + 64;
185 len -= 64;
186 }
187 else
188#endif
189 {
190 __sha256_process_block (buffer, len & ~63, ctx);
191 buffer = (const char *) buffer + (len & ~63);
192 len &= 63;
193 }
194 }
195
196 /* Move remaining bytes into internal buffer. */
197 if (len > 0)
198 {
199 size_t left_over = ctx->buflen;
200
201 memcpy (&ctx->buffer[left_over], buffer, len);
202 left_over += len;
203 if (left_over >= 64)
204 {
205 __sha256_process_block (ctx->buffer, 64, ctx);
206 left_over -= 64;
207 memcpy (ctx->buffer, &ctx->buffer[64], left_over);
208 }
209 ctx->buflen = left_over;
210 }
211}
212
213#include <sha256-block.c>
214

source code of glibc/crypt/sha256.c