380 lines
11 KiB
C
380 lines
11 KiB
C
/* Functions to compute MD4 message digest of files or memory blocks.
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according to the definition of MD4 in RFC 1320 from April 1992.
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Copyright (C) 1995-1997, 1999-2003, 2005-2006, 2008-2011 Free Software
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Foundation, Inc.
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This program is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2, or (at your option) any
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later version.
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This program 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
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
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/* Adapted by Simon Josefsson from gnulib md5.? and Libgcrypt
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cipher/md4.c . */
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#include "md4.h"
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#include <stdalign.h>
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#include <stdlib.h>
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#include <string.h>
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#if USE_UNLOCKED_IO
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# include "unlocked-io.h"
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#endif
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#ifdef WORDS_BIGENDIAN
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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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#define BLOCKSIZE 32768
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#if BLOCKSIZE % 64 != 0
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# error "invalid BLOCKSIZE"
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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 1320, 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 1320, 3.3: Step 3) */
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void
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md4_init_ctx (struct md4_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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/* Copy the 4 byte value from v into the memory location pointed to by *cp,
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If your architecture allows unaligned access this is equivalent to
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* (uint32_t *) cp = v */
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static inline void
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set_uint32 (char *cp, uint32_t v)
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{
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memcpy (cp, &v, sizeof v);
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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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void *
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md4_read_ctx (const struct md4_ctx *ctx, void *resbuf)
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{
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char *r = resbuf;
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set_uint32 (r + 0 * sizeof ctx->A, SWAP (ctx->A));
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set_uint32 (r + 1 * sizeof ctx->B, SWAP (ctx->B));
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set_uint32 (r + 2 * sizeof ctx->C, SWAP (ctx->C));
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set_uint32 (r + 3 * sizeof ctx->D, 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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void *
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md4_finish_ctx (struct md4_ctx *ctx, 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->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 (&((char*)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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ctx->buffer[(bytes + pad) / 4] = SWAP (ctx->total[0] << 3);
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ctx->buffer[(bytes + pad) / 4 + 1] = SWAP ((ctx->total[1] << 3) |
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(ctx->total[0] >> 29));
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/* Process last bytes. */
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md4_process_block (ctx->buffer, bytes + pad + 8, ctx);
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return md4_read_ctx (ctx, resbuf);
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}
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/* Compute MD4 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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md4_stream (FILE * stream, void *resblock)
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{
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struct md4_ctx ctx;
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size_t sum;
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char *buffer = malloc (BLOCKSIZE + 72);
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if (!buffer)
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return 1;
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/* Initialize the computation context. */
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md4_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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while (1)
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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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if (sum == BLOCKSIZE)
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break;
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if (n == 0)
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{
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/* Check for the error flag IFF N == 0, so that we don't
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exit the loop after a partial read due to e.g., EAGAIN
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or EWOULDBLOCK. */
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if (ferror (stream))
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{
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free (buffer);
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return 1;
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}
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goto process_partial_block;
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}
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/* We've read at least one byte, so ignore errors. But always
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check for EOF, since feof may be true even though N > 0.
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Otherwise, we could end up calling fread after EOF. */
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if (feof (stream))
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goto process_partial_block;
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}
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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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md4_process_block (buffer, BLOCKSIZE, &ctx);
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}
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process_partial_block:;
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/* Process any remaining bytes. */
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if (sum > 0)
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md4_process_bytes (buffer, sum, &ctx);
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/* Construct result in desired memory. */
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md4_finish_ctx (&ctx, resblock);
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free (buffer);
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return 0;
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}
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/* Compute MD4 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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md4_buffer (const char *buffer, size_t len, void *resblock)
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{
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struct md4_ctx ctx;
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/* Initialize the computation context. */
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md4_init_ctx (&ctx);
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/* Process whole buffer but last len % 64 bytes. */
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md4_process_bytes (buffer, len, &ctx);
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/* Put result in desired memory area. */
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return md4_finish_ctx (&ctx, resblock);
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}
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void
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md4_process_bytes (const void *buffer, size_t len, struct md4_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 (&((char*)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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md4_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, &((char*)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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# define UNALIGNED_P(p) ((uintptr_t) (p) % alignof (uint32_t) != 0)
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if (UNALIGNED_P (buffer))
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while (len > 64)
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{
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md4_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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md4_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 in 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 (&((char*)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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md4_process_block (ctx->buffer, 64, ctx);
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left_over -= 64;
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memcpy (ctx->buffer, &ctx->buffer[16], 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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/* --- Code below is the primary difference between md5.c and md4.c --- */
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/* MD4 round constants */
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#define K1 0x5a827999
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#define K2 0x6ed9eba1
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/* Round functions. */
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#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
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#define G(x, y, z) (((x) & (y)) | ((x) & (z)) | ((y) & (z)))
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#define H(x, y, z) ((x) ^ (y) ^ (z))
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#define rol(x, n) (((x) << (n)) | ((uint32_t) (x) >> (32 - (n))))
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#define R1(a,b,c,d,k,s) a=rol(a+F(b,c,d)+x[k],s);
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#define R2(a,b,c,d,k,s) a=rol(a+G(b,c,d)+x[k]+K1,s);
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#define R3(a,b,c,d,k,s) a=rol(a+H(b,c,d)+x[k]+K2,s);
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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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md4_process_block (const void *buffer, size_t len, struct md4_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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const uint32_t *endp = words + nwords;
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uint32_t x[16];
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uint32_t A = ctx->A;
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uint32_t B = ctx->B;
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uint32_t C = ctx->C;
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uint32_t D = ctx->D;
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/* First increment the byte count. RFC 1320 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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int t;
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for (t = 0; t < 16; t++)
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{
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x[t] = SWAP (*words);
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words++;
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}
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/* Round 1. */
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R1 (A, B, C, D, 0, 3);
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R1 (D, A, B, C, 1, 7);
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R1 (C, D, A, B, 2, 11);
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R1 (B, C, D, A, 3, 19);
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R1 (A, B, C, D, 4, 3);
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R1 (D, A, B, C, 5, 7);
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R1 (C, D, A, B, 6, 11);
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R1 (B, C, D, A, 7, 19);
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R1 (A, B, C, D, 8, 3);
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R1 (D, A, B, C, 9, 7);
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R1 (C, D, A, B, 10, 11);
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R1 (B, C, D, A, 11, 19);
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R1 (A, B, C, D, 12, 3);
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R1 (D, A, B, C, 13, 7);
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R1 (C, D, A, B, 14, 11);
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R1 (B, C, D, A, 15, 19);
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/* Round 2. */
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R2 (A, B, C, D, 0, 3);
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R2 (D, A, B, C, 4, 5);
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R2 (C, D, A, B, 8, 9);
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R2 (B, C, D, A, 12, 13);
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R2 (A, B, C, D, 1, 3);
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R2 (D, A, B, C, 5, 5);
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R2 (C, D, A, B, 9, 9);
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R2 (B, C, D, A, 13, 13);
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R2 (A, B, C, D, 2, 3);
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R2 (D, A, B, C, 6, 5);
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R2 (C, D, A, B, 10, 9);
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R2 (B, C, D, A, 14, 13);
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R2 (A, B, C, D, 3, 3);
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R2 (D, A, B, C, 7, 5);
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R2 (C, D, A, B, 11, 9);
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R2 (B, C, D, A, 15, 13);
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/* Round 3. */
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R3 (A, B, C, D, 0, 3);
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R3 (D, A, B, C, 8, 9);
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R3 (C, D, A, B, 4, 11);
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R3 (B, C, D, A, 12, 15);
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R3 (A, B, C, D, 2, 3);
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R3 (D, A, B, C, 10, 9);
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R3 (C, D, A, B, 6, 11);
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R3 (B, C, D, A, 14, 15);
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R3 (A, B, C, D, 1, 3);
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R3 (D, A, B, C, 9, 9);
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R3 (C, D, A, B, 5, 11);
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R3 (B, C, D, A, 13, 15);
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R3 (A, B, C, D, 3, 3);
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R3 (D, A, B, C, 11, 9);
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R3 (C, D, A, B, 7, 11);
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R3 (B, C, D, A, 15, 15);
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A = ctx->A += A;
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B = ctx->B += B;
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C = ctx->C += C;
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D = ctx->D += D;
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}
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}
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