403 lines
12 KiB
C
Executable File
403 lines
12 KiB
C
Executable File
/* md5.c - Functions to compute MD5 message digest of files or memory blocks
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according to the definition of MD5 in RFC 1321 from April 1992.
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Copyright (C) 1995, 1996 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 Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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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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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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/* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995. */
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#ifdef USE_MD5
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#include <stdlib.h>
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#ifdef HAVE_STRING_H
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# include <string.h>
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#else
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# include <strings.h>
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#endif
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#include "md5.h"
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#ifdef _LIBC
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# include <endian.h>
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# if __BYTE_ORDER == __BIG_ENDIAN
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# define WORDS_BIGENDIAN 1
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# endif
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#endif
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#if defined(WORDS_BIGENDIAN) || defined(_BIG_ENDIAN)
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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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#else
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# define SWAP(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. (RFC 1321, 3.1: Step 1) */
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static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ... */ };
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/* Initialize structure containing state of computation.
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(RFC 1321, 3.3: Step 3) */
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void
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md5_init_ctx (struct md5_ctx *ctx)
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{
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ctx->A = 0x67452301;
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ctx->B = 0xefcdab89;
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ctx->C = 0x98badcfe;
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ctx->D = 0x10325476;
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ctx->total[0] = ctx->total[1] = 0;
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ctx->buflen = 0;
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}
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/* Put result from CTX in first 16 bytes following RESBUF. The result
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must be in little endian byte order.
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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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md5_read_ctx (const struct md5_ctx *ctx, void *resbuf)
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{
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((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
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((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
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((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
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((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
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return resbuf;
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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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md5_finish_ctx (struct md5_ctx *ctx, void *resbuf)
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{
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/* Take yet unprocessed bytes into account. */
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md5_uint32 bytes = ctx->buflen;
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size_t pad;
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/* Now count remaining bytes. */
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ctx->total[0] += bytes;
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if (ctx->total[0] < bytes)
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++ctx->total[1];
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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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*(md5_uint32 *) &ctx->buffer[bytes + pad] = SWAP (ctx->total[0] << 3);
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*(md5_uint32 *) &ctx->buffer[bytes + pad + 4] = SWAP ((ctx->total[1] << 3) |
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(ctx->total[0] >> 29));
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/* Process last bytes. */
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md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
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return md5_read_ctx (ctx, resbuf);
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}
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/* Compute MD5 message digest for bytes read from STREAM. The
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resulting message digest number will be written into the 16 bytes
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beginning at RESBLOCK. */
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int
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md5_stream (FILE *stream, void *resblock)
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{
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/* Important: BLOCKSIZE must be a multiple of 64. */
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#define BLOCKSIZE 4096
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struct md5_ctx ctx;
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char buffer[BLOCKSIZE + 72];
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size_t sum;
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/* Initialize the computation context. */
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md5_init_ctx (&ctx);
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/* Iterate over full file contents. */
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while (1)
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{
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/* We read the file in blocks of BLOCKSIZE bytes. One call of the
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computation function processes the whole buffer so that with the
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next round of the loop another block can be read. */
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size_t n;
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sum = 0;
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/* Read block. Take care for partial reads. */
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do
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{
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n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
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sum += n;
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}
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while (sum < BLOCKSIZE && n != 0);
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if (n == 0 && ferror (stream))
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return 1;
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/* If end of file is reached, end the loop. */
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if (n == 0)
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break;
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/* Process buffer with BLOCKSIZE bytes. Note that
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BLOCKSIZE % 64 == 0
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*/
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md5_process_block (buffer, BLOCKSIZE, &ctx);
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}
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/* Add the last bytes if necessary. */
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if (sum > 0)
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md5_process_bytes (buffer, sum, &ctx);
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/* Construct result in desired memory. */
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md5_finish_ctx (&ctx, resblock);
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return 0;
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}
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/* Compute MD5 message digest for LEN bytes beginning at BUFFER. The
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result is always in little endian byte order, so that a byte-wise
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output yields to the wanted ASCII representation of the message
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digest. */
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void *
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md5_buffer (const char *buffer, size_t len, void *resblock)
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{
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struct md5_ctx ctx;
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/* Initialize the computation context. */
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md5_init_ctx (&ctx);
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/* Process whole buffer but last len % 64 bytes. */
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md5_process_bytes (buffer, len, &ctx);
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/* Put result in desired memory area. */
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return md5_finish_ctx (&ctx, resblock);
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}
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void
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md5_process_bytes (const void *buffer, size_t len, struct md5_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 (left_over + add > 64)
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{
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md5_process_block (ctx->buffer, (left_over + add) & ~63, ctx);
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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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(left_over + add) & 63);
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ctx->buflen = (left_over + add) & 63;
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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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md5_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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/* Move remaining bytes in internal buffer. */
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if (len > 0)
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{
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memcpy (ctx->buffer, buffer, len);
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ctx->buflen = len;
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}
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}
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/* These are the four functions used in the four steps of the MD5 algorithm
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and defined in the RFC 1321. The first function is a little bit optimized
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(as found in Colin Plumbs public domain implementation). */
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/* #define FF(b, c, d) ((b & c) | (~b & d)) */
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#define FF(b, c, d) (d ^ (b & (c ^ d)))
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#define FG(b, c, d) FF (d, b, c)
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#define FH(b, c, d) (b ^ c ^ d)
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#define FI(b, c, d) (c ^ (b | ~d))
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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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void
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md5_process_block (const void *buffer, size_t len, struct md5_ctx *ctx)
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{
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md5_uint32 correct_words[16];
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const md5_uint32 *words = buffer;
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size_t nwords = len / sizeof (md5_uint32);
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const md5_uint32 *endp = words + nwords;
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md5_uint32 A = ctx->A;
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md5_uint32 B = ctx->B;
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md5_uint32 C = ctx->C;
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md5_uint32 D = ctx->D;
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/* First increment the byte count. RFC 1321 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. Do a double word increment. */
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ctx->total[0] += len;
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if (ctx->total[0] < len)
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++ctx->total[1];
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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 (words < endp)
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{
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md5_uint32 *cwp = correct_words;
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md5_uint32 A_save = A;
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md5_uint32 B_save = B;
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md5_uint32 C_save = C;
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md5_uint32 D_save = D;
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/* First round: using the given function, the context and a constant
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the next context is computed. Because the algorithms processing
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unit is a 32-bit word and it is determined to work on words in
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little endian byte order we perhaps have to change the byte order
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before the computation. To reduce the work for the next steps
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we store the swapped words in the array CORRECT_WORDS. */
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#define OP(a, b, c, d, s, T) \
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do \
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{ \
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a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T; \
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++words; \
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CYCLIC (a, s); \
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a += b; \
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} \
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while (0)
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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 = (w << s) | (w >> (32 - s)))
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/* Before we start, one word to the strange constants.
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They are defined in RFC 1321 as
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T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
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*/
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/* Round 1. */
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OP (A, B, C, D, 7, 0xd76aa478);
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OP (D, A, B, C, 12, 0xe8c7b756);
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OP (C, D, A, B, 17, 0x242070db);
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OP (B, C, D, A, 22, 0xc1bdceee);
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OP (A, B, C, D, 7, 0xf57c0faf);
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OP (D, A, B, C, 12, 0x4787c62a);
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OP (C, D, A, B, 17, 0xa8304613);
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OP (B, C, D, A, 22, 0xfd469501);
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OP (A, B, C, D, 7, 0x698098d8);
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OP (D, A, B, C, 12, 0x8b44f7af);
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OP (C, D, A, B, 17, 0xffff5bb1);
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OP (B, C, D, A, 22, 0x895cd7be);
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OP (A, B, C, D, 7, 0x6b901122);
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OP (D, A, B, C, 12, 0xfd987193);
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OP (C, D, A, B, 17, 0xa679438e);
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OP (B, C, D, A, 22, 0x49b40821);
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/* For the second to fourth round we have the possibly swapped words
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in CORRECT_WORDS. Redefine the macro to take an additional first
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argument specifying the function to use. */
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#undef OP
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#define OP(f, a, b, c, d, k, s, T) \
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do \
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{ \
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a += f (b, c, d) + correct_words[k] + T; \
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CYCLIC (a, s); \
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a += b; \
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} \
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while (0)
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/* Round 2. */
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OP (FG, A, B, C, D, 1, 5, 0xf61e2562);
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OP (FG, D, A, B, C, 6, 9, 0xc040b340);
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OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
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OP (FG, B, C, D, A, 0, 20, 0xe9b6c7aa);
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OP (FG, A, B, C, D, 5, 5, 0xd62f105d);
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OP (FG, D, A, B, C, 10, 9, 0x02441453);
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OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
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OP (FG, B, C, D, A, 4, 20, 0xe7d3fbc8);
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OP (FG, A, B, C, D, 9, 5, 0x21e1cde6);
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OP (FG, D, A, B, C, 14, 9, 0xc33707d6);
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OP (FG, C, D, A, B, 3, 14, 0xf4d50d87);
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OP (FG, B, C, D, A, 8, 20, 0x455a14ed);
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OP (FG, A, B, C, D, 13, 5, 0xa9e3e905);
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OP (FG, D, A, B, C, 2, 9, 0xfcefa3f8);
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OP (FG, C, D, A, B, 7, 14, 0x676f02d9);
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OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
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/* Round 3. */
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OP (FH, A, B, C, D, 5, 4, 0xfffa3942);
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OP (FH, D, A, B, C, 8, 11, 0x8771f681);
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OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
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OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
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OP (FH, A, B, C, D, 1, 4, 0xa4beea44);
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OP (FH, D, A, B, C, 4, 11, 0x4bdecfa9);
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OP (FH, C, D, A, B, 7, 16, 0xf6bb4b60);
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OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
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OP (FH, A, B, C, D, 13, 4, 0x289b7ec6);
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OP (FH, D, A, B, C, 0, 11, 0xeaa127fa);
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OP (FH, C, D, A, B, 3, 16, 0xd4ef3085);
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OP (FH, B, C, D, A, 6, 23, 0x04881d05);
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OP (FH, A, B, C, D, 9, 4, 0xd9d4d039);
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OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
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OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
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OP (FH, B, C, D, A, 2, 23, 0xc4ac5665);
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/* Round 4. */
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OP (FI, A, B, C, D, 0, 6, 0xf4292244);
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OP (FI, D, A, B, C, 7, 10, 0x432aff97);
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OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
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OP (FI, B, C, D, A, 5, 21, 0xfc93a039);
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OP (FI, A, B, C, D, 12, 6, 0x655b59c3);
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OP (FI, D, A, B, C, 3, 10, 0x8f0ccc92);
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OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
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OP (FI, B, C, D, A, 1, 21, 0x85845dd1);
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OP (FI, A, B, C, D, 8, 6, 0x6fa87e4f);
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OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
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OP (FI, C, D, A, B, 6, 15, 0xa3014314);
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OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
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OP (FI, A, B, C, D, 4, 6, 0xf7537e82);
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OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
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OP (FI, C, D, A, B, 2, 15, 0x2ad7d2bb);
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OP (FI, B, C, D, A, 9, 21, 0xeb86d391);
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/* Add the starting values of the context. */
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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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}
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/* Put checksum in context given as argument. */
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ctx->A = A;
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ctx->B = B;
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ctx->C = C;
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ctx->D = D;
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}
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#endif
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