/* 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;
}
}