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- /* Functions to compute SHA256 message digest of files or memory blocks.
- according to the definition of SHA256 in FIPS 180-2.
- Copyright (C) 2007 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
- The GNU C Library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public
- License as published by the Free Software Foundation; either
- version 2.1 of the License, or (at your option) any later version.
- The GNU C Library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
- You should have received a copy of the GNU Lesser General Public
- License along with the GNU C Library; if not, see
- <http://www.gnu.org/licenses/>. */
- /* Written by Ulrich Drepper <drepper@redhat.com>, 2007. */
- #ifdef HAVE_CONFIG_H
- # include <config.h>
- #endif
- #include <endian.h>
- #include <stdlib.h>
- #include <string.h>
- #include <sys/types.h>
- #include "sha256.h"
- #if __BYTE_ORDER == __LITTLE_ENDIAN
- # ifdef _LIBC
- # include <byteswap.h>
- # define SWAP(n) bswap_32 (n)
- # else
- # define SWAP(n) \
- (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
- # endif
- #else
- # define SWAP(n) (n)
- #endif
- /* This array contains the bytes used to pad the buffer to the next
- 64-byte boundary. (FIPS 180-2:5.1.1) */
- static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ... */ };
- /* Constants for SHA256 from FIPS 180-2:4.2.2. */
- static const uint32_t K[64] =
- {
- 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
- 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
- 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
- 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
- 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
- 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
- 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
- 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
- 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
- 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
- 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
- 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
- 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
- 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
- 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
- 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
- };
- /* Process LEN bytes of BUFFER, accumulating context into CTX.
- It is assumed that LEN % 64 == 0. */
- static void
- sha256_process_block (const void *buffer, size_t len, struct sha256_ctx *ctx)
- {
- const uint32_t *words = buffer;
- size_t nwords = len / sizeof (uint32_t);
- uint32_t a = ctx->H[0];
- uint32_t b = ctx->H[1];
- uint32_t c = ctx->H[2];
- uint32_t d = ctx->H[3];
- uint32_t e = ctx->H[4];
- uint32_t f = ctx->H[5];
- uint32_t g = ctx->H[6];
- uint32_t h = ctx->H[7];
- /* First increment the byte count. FIPS 180-2 specifies the possible
- length of the file up to 2^64 bits. Here we only compute the
- number of bytes. Do a double word increment. */
- ctx->total[0] += len;
- if (ctx->total[0] < len)
- ++ctx->total[1];
- /* Process all bytes in the buffer with 64 bytes in each round of
- the loop. */
- while (nwords > 0)
- {
- uint32_t W[64];
- uint32_t a_save = a;
- uint32_t b_save = b;
- uint32_t c_save = c;
- uint32_t d_save = d;
- uint32_t e_save = e;
- uint32_t f_save = f;
- uint32_t g_save = g;
- uint32_t h_save = h;
- /* Operators defined in FIPS 180-2:4.1.2. */
- #define _Ch(x, y, z) ((x & y) ^ (~x & z))
- #define _Maj(x, y, z) ((x & y) ^ (x & z) ^ (y & z))
- #define _S0(x) (CYCLIC (x, 2) ^ CYCLIC (x, 13) ^ CYCLIC (x, 22))
- #define _S1(x) (CYCLIC (x, 6) ^ CYCLIC (x, 11) ^ CYCLIC (x, 25))
- #define _R0(x) (CYCLIC (x, 7) ^ CYCLIC (x, 18) ^ (x >> 3))
- #define _R1(x) (CYCLIC (x, 17) ^ CYCLIC (x, 19) ^ (x >> 10))
- /* It is unfortunate that C does not provide an operator for
- cyclic rotation. Hope the C compiler is smart enough. */
- #define CYCLIC(w, s) ((w >> s) | (w << (32 - s)))
- /* Compute the message schedule according to FIPS 180-2:6.2.2 step 2. */
- for (unsigned int t = 0; t < 16; ++t)
- {
- W[t] = SWAP (*words);
- ++words;
- }
- for (unsigned int t = 16; t < 64; ++t)
- W[t] = _R1 (W[t - 2]) + W[t - 7] + _R0 (W[t - 15]) + W[t - 16];
- /* The actual computation according to FIPS 180-2:6.2.2 step 3. */
- for (unsigned int t = 0; t < 64; ++t)
- {
- uint32_t T1 = h + _S1 (e) + _Ch (e, f, g) + K[t] + W[t];
- uint32_t T2 = _S0 (a) + _Maj (a, b, c);
- h = g;
- g = f;
- f = e;
- e = d + T1;
- d = c;
- c = b;
- b = a;
- a = T1 + T2;
- }
- /* Add the starting values of the context according to FIPS 180-2:6.2.2
- step 4. */
- a += a_save;
- b += b_save;
- c += c_save;
- d += d_save;
- e += e_save;
- f += f_save;
- g += g_save;
- h += h_save;
- /* Prepare for the next round. */
- nwords -= 16;
- }
- /* Put checksum in context given as argument. */
- ctx->H[0] = a;
- ctx->H[1] = b;
- ctx->H[2] = c;
- ctx->H[3] = d;
- ctx->H[4] = e;
- ctx->H[5] = f;
- ctx->H[6] = g;
- ctx->H[7] = h;
- }
- /* Initialize structure containing state of computation.
- (FIPS 180-2:5.3.2) */
- void
- __sha256_init_ctx (struct sha256_ctx *ctx)
- {
- ctx->H[0] = 0x6a09e667;
- ctx->H[1] = 0xbb67ae85;
- ctx->H[2] = 0x3c6ef372;
- ctx->H[3] = 0xa54ff53a;
- ctx->H[4] = 0x510e527f;
- ctx->H[5] = 0x9b05688c;
- ctx->H[6] = 0x1f83d9ab;
- ctx->H[7] = 0x5be0cd19;
- ctx->total[0] = ctx->total[1] = 0;
- ctx->buflen = 0;
- }
- /* Process the remaining bytes in the internal buffer and the usual
- prolog according to the standard and write the result to RESBUF.
- IMPORTANT: On some systems it is required that RESBUF is correctly
- aligned for a 32 bits value. */
- void *
- __sha256_finish_ctx (struct sha256_ctx *ctx, void *resbuf)
- {
- /* Take yet unprocessed bytes into account. */
- uint32_t bytes = ctx->buflen;
- size_t pad;
- /* Now count remaining bytes. */
- ctx->total[0] += bytes;
- if (ctx->total[0] < bytes)
- ++ctx->total[1];
- pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
- memcpy (&ctx->buffer[bytes], fillbuf, pad);
- /* Put the 64-bit file length in *bits* at the end of the buffer. */
- *(uint32_t *) &ctx->buffer[bytes + pad + 4] = SWAP (ctx->total[0] << 3);
- *(uint32_t *) &ctx->buffer[bytes + pad] = SWAP ((ctx->total[1] << 3) |
- (ctx->total[0] >> 29));
- /* Process last bytes. */
- sha256_process_block (ctx->buffer, bytes + pad + 8, ctx);
- /* Put result from CTX in first 32 bytes following RESBUF. */
- for (unsigned int i = 0; i < 8; ++i)
- ((uint32_t *) resbuf)[i] = SWAP (ctx->H[i]);
- return resbuf;
- }
- void
- __sha256_process_bytes (const void *buffer, size_t len, struct sha256_ctx *ctx)
- {
- /* When we already have some bits in our internal buffer concatenate
- both inputs first. */
- if (ctx->buflen != 0)
- {
- size_t left_over = ctx->buflen;
- size_t add = 128 - left_over > len ? len : 128 - left_over;
- memcpy (&ctx->buffer[left_over], buffer, add);
- ctx->buflen += add;
- if (ctx->buflen > 64)
- {
- sha256_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
- ctx->buflen &= 63;
- /* The regions in the following copy operation cannot overlap. */
- memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
- ctx->buflen);
- }
- buffer = (const char *) buffer + add;
- len -= add;
- }
- /* Process available complete blocks. */
- if (len >= 64)
- {
- #if __GNUC__ >= 2
- # define UNALIGNED_P(p) (((uintptr_t) p) % __alignof__ (uint32_t) != 0)
- #else
- # define UNALIGNED_P(p) (((uintptr_t) p) % sizeof (uint32_t) != 0)
- #endif
- if (UNALIGNED_P (buffer))
- while (len > 64)
- {
- sha256_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
- buffer = (const char *) buffer + 64;
- len -= 64;
- }
- else
- {
- sha256_process_block (buffer, len & ~63, ctx);
- buffer = (const char *) buffer + (len & ~63);
- len &= 63;
- }
- }
- /* Move remaining bytes into internal buffer. */
- if (len > 0)
- {
- size_t left_over = ctx->buflen;
- memcpy (&ctx->buffer[left_over], buffer, len);
- left_over += len;
- if (left_over >= 64)
- {
- sha256_process_block (ctx->buffer, 64, ctx);
- left_over -= 64;
- memcpy (ctx->buffer, &ctx->buffer[64], left_over);
- }
- ctx->buflen = left_over;
- }
- }
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