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318 lines
8.9 KiB
C
318 lines
8.9 KiB
C
/* Functions to compute SHA256 message digest of files or memory blocks.
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according to the definition of SHA256 in FIPS 180-2.
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Copyright (C) 2007, 2011 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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/* Written by Ulrich Drepper <drepper@redhat.com>, 2007. */
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <endian.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include "sha256.h"
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#if __BYTE_ORDER == __LITTLE_ENDIAN
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# ifdef _LIBC
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# include <byteswap.h>
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# define SWAP(n) bswap_32 (n)
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# define SWAP64(n) bswap_64 (n)
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# else
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# define SWAP(n) \
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(((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
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# define SWAP64(n) \
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(((n) << 56) \
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| (((n) & 0xff00) << 40) \
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| (((n) & 0xff0000) << 24) \
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| (((n) & 0xff000000) << 8) \
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| (((n) >> 8) & 0xff000000) \
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| (((n) >> 24) & 0xff0000) \
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| (((n) >> 40) & 0xff00) \
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| ((n) >> 56))
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# endif
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#else
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# define SWAP(n) (n)
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# define SWAP64(n) (n)
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#endif
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/* This array contains the bytes used to pad the buffer to the next
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64-byte boundary. (FIPS 180-2:5.1.1) */
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static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ... */ };
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/* Constants for SHA256 from FIPS 180-2:4.2.2. */
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static const uint32_t K[64] =
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{
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0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
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0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
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0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
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0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
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0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
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0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
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0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
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0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
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0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
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0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
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0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
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0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
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0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
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0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
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0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
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0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
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};
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/* Process LEN bytes of BUFFER, accumulating context into CTX.
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It is assumed that LEN % 64 == 0. */
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static void
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sha256_process_block (const void *buffer, size_t len, struct sha256_ctx *ctx)
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{
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const uint32_t *words = buffer;
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size_t nwords = len / sizeof (uint32_t);
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uint32_t a = ctx->H[0];
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uint32_t b = ctx->H[1];
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uint32_t c = ctx->H[2];
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uint32_t d = ctx->H[3];
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uint32_t e = ctx->H[4];
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uint32_t f = ctx->H[5];
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uint32_t g = ctx->H[6];
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uint32_t h = ctx->H[7];
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/* First increment the byte count. FIPS 180-2 specifies the possible
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length of the file up to 2^64 bits. Here we only compute the
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number of bytes. */
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ctx->total64 += len;
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/* Process all bytes in the buffer with 64 bytes in each round of
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the loop. */
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while (nwords > 0)
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{
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uint32_t W[64];
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uint32_t a_save = a;
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uint32_t b_save = b;
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uint32_t c_save = c;
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uint32_t d_save = d;
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uint32_t e_save = e;
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uint32_t f_save = f;
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uint32_t g_save = g;
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uint32_t h_save = h;
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/* Operators defined in FIPS 180-2:4.1.2. */
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#define Ch(x, y, z) ((x & y) ^ (~x & z))
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#define Maj(x, y, z) ((x & y) ^ (x & z) ^ (y & z))
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#define S0(x) (CYCLIC (x, 2) ^ CYCLIC (x, 13) ^ CYCLIC (x, 22))
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#define S1(x) (CYCLIC (x, 6) ^ CYCLIC (x, 11) ^ CYCLIC (x, 25))
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#define R0(x) (CYCLIC (x, 7) ^ CYCLIC (x, 18) ^ (x >> 3))
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#define R1(x) (CYCLIC (x, 17) ^ CYCLIC (x, 19) ^ (x >> 10))
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/* It is unfortunate that C does not provide an operator for
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cyclic rotation. Hope the C compiler is smart enough. */
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#define CYCLIC(w, s) ((w >> s) | (w << (32 - s)))
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/* Compute the message schedule according to FIPS 180-2:6.2.2 step 2. */
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for (unsigned int t = 0; t < 16; ++t)
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{
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W[t] = SWAP (*words);
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++words;
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}
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for (unsigned int t = 16; t < 64; ++t)
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W[t] = R1 (W[t - 2]) + W[t - 7] + R0 (W[t - 15]) + W[t - 16];
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/* The actual computation according to FIPS 180-2:6.2.2 step 3. */
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for (unsigned int t = 0; t < 64; ++t)
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{
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uint32_t T1 = h + S1 (e) + Ch (e, f, g) + K[t] + W[t];
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uint32_t T2 = S0 (a) + Maj (a, b, c);
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h = g;
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g = f;
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f = e;
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e = d + T1;
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d = c;
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c = b;
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b = a;
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a = T1 + T2;
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}
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/* Add the starting values of the context according to FIPS 180-2:6.2.2
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step 4. */
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a += a_save;
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b += b_save;
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c += c_save;
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d += d_save;
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e += e_save;
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f += f_save;
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g += g_save;
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h += h_save;
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/* Prepare for the next round. */
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nwords -= 16;
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}
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/* Put checksum in context given as argument. */
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ctx->H[0] = a;
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ctx->H[1] = b;
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ctx->H[2] = c;
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ctx->H[3] = d;
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ctx->H[4] = e;
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ctx->H[5] = f;
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ctx->H[6] = g;
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ctx->H[7] = h;
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}
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/* Initialize structure containing state of computation.
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(FIPS 180-2:5.3.2) */
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void
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__sha256_init_ctx (ctx)
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struct sha256_ctx *ctx;
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{
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ctx->H[0] = 0x6a09e667;
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ctx->H[1] = 0xbb67ae85;
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ctx->H[2] = 0x3c6ef372;
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ctx->H[3] = 0xa54ff53a;
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ctx->H[4] = 0x510e527f;
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ctx->H[5] = 0x9b05688c;
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ctx->H[6] = 0x1f83d9ab;
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ctx->H[7] = 0x5be0cd19;
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ctx->total64 = 0;
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ctx->buflen = 0;
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}
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/* Process the remaining bytes in the internal buffer and the usual
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prolog according to the standard and write the result to RESBUF.
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IMPORTANT: On some systems it is required that RESBUF is correctly
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aligned for a 32 bits value. */
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void *
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__sha256_finish_ctx (ctx, resbuf)
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struct sha256_ctx *ctx;
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void *resbuf;
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{
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/* Take yet unprocessed bytes into account. */
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uint32_t bytes = ctx->buflen;
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size_t pad;
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/* Now count remaining bytes. */
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ctx->total64 += bytes;
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pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
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memcpy (&ctx->buffer[bytes], fillbuf, pad);
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/* Put the 64-bit file length in *bits* at the end of the buffer. */
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#ifdef _STRING_ARCH_unaligned
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*(uint64_t *) &ctx->buffer[bytes + pad] = SWAP64 (ctx->total64 << 3);
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#else
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*(uint32_t *) &ctx->buffer[bytes + pad + 4]
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= SWAP (ctx->total[TOTAL64_low] << 3);
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*(uint32_t *) &ctx->buffer[bytes + pad]
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= SWAP ((ctx->total[TOTAL64_high] << 3) |
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(ctx->total[TOTAL64_low] >> 29));
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#endif
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/* Process last bytes. */
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sha256_process_block (ctx->buffer, bytes + pad + 8, ctx);
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/* Put result from CTX in first 32 bytes following RESBUF. */
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for (unsigned int i = 0; i < 8; ++i)
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((uint32_t *) resbuf)[i] = SWAP (ctx->H[i]);
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return resbuf;
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}
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void
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__sha256_process_bytes (buffer, len, ctx)
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const void *buffer;
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size_t len;
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struct sha256_ctx *ctx;
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{
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/* When we already have some bits in our internal buffer concatenate
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both inputs first. */
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if (ctx->buflen != 0)
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{
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size_t left_over = ctx->buflen;
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size_t add = 128 - left_over > len ? len : 128 - left_over;
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memcpy (&ctx->buffer[left_over], buffer, add);
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ctx->buflen += add;
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if (ctx->buflen > 64)
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{
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sha256_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
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ctx->buflen &= 63;
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/* The regions in the following copy operation cannot overlap. */
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memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
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ctx->buflen);
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}
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buffer = (const char *) buffer + add;
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len -= add;
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}
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/* Process available complete blocks. */
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if (len >= 64)
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{
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#if !_STRING_ARCH_unaligned
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/* To check alignment gcc has an appropriate operator. Other
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compilers don't. */
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# if __GNUC__ >= 2
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# define UNALIGNED_P(p) (((uintptr_t) p) % __alignof__ (uint32_t) != 0)
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# else
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# define UNALIGNED_P(p) (((uintptr_t) p) % sizeof (uint32_t) != 0)
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# endif
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if (UNALIGNED_P (buffer))
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while (len > 64)
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{
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sha256_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
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buffer = (const char *) buffer + 64;
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len -= 64;
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}
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else
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#endif
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{
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sha256_process_block (buffer, len & ~63, ctx);
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buffer = (const char *) buffer + (len & ~63);
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len &= 63;
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}
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}
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/* Move remaining bytes into internal buffer. */
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if (len > 0)
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{
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size_t left_over = ctx->buflen;
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memcpy (&ctx->buffer[left_over], buffer, len);
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left_over += len;
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if (left_over >= 64)
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{
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sha256_process_block (ctx->buffer, 64, ctx);
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left_over -= 64;
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memcpy (ctx->buffer, &ctx->buffer[64], left_over);
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}
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ctx->buflen = left_over;
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}
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}
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