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/* Functions to compute MD2 message digest of files or memory blocks.
according to the definition of MD2 in RFC 1319 from April 1992.
Copyright (C) 1995-1997, 1999-2003, 2005-2006, 2008-2024 Free Software
Foundation, Inc.
This file 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.
This file 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 this program. If not, see <https://www.gnu.org/licenses/>. */
/* Adapted by Simon Josefsson from public domain Libtomcrypt 1.06 by
Tom St Denis. */
#include <config.h>
/* Specification. */
#include "md2.h"
#include <string.h>
#include <sys/types.h>
#include <minmax.h>
static void md2_update_chksum (struct md2_ctx *md);
static void md2_compress (struct md2_ctx *md);
/* Initialize structure containing state of computation.
(RFC 1319, 3.3: Step 3) */
void
md2_init_ctx (struct md2_ctx *ctx)
{
memset (ctx->X, 0, sizeof (ctx->X));
memset (ctx->chksum, 0, sizeof (ctx->chksum));
memset (ctx->buf, 0, sizeof (ctx->buf));
ctx->curlen = 0;
}
/* Put result from CTX in first 16 bytes following RESBUF. The result
must be in little endian byte order. */
void *
md2_read_ctx (const struct md2_ctx *ctx, void *resbuf)
{
memcpy (resbuf, ctx->X, 16);
return resbuf;
}
/* Process the remaining bytes in the internal buffer and the usual
prolog according to the standard and write the result to RESBUF. */
void *
md2_finish_ctx (struct md2_ctx *ctx, void *resbuf)
{
unsigned long i, k;
/* pad the message */
k = 16 - ctx->curlen;
for (i = ctx->curlen; i < 16; i++)
{
ctx->buf[i] = (unsigned char) k;
}
/* hash and update */
md2_compress (ctx);
md2_update_chksum (ctx);
/* hash checksum */
memcpy (ctx->buf, ctx->chksum, 16);
md2_compress (ctx);
return md2_read_ctx (ctx, resbuf);
}
/* Compute MD5 message digest for LEN bytes beginning at BUFFER. The
result is always in little endian byte order, so that a byte-wise
output yields to the wanted ASCII representation of the message
digest. */
void *
md2_buffer (const char *buffer, size_t len, void *resblock)
{
struct md2_ctx ctx;
/* Initialize the computation context. */
md2_init_ctx (&ctx);
/* Process whole buffer but last len % 64 bytes. */
md2_process_block (buffer, len, &ctx);
/* Put result in desired memory area. */
return md2_finish_ctx (&ctx, resblock);
}
void
md2_process_bytes (const void *buffer, size_t len, struct md2_ctx *ctx)
{
const char *in = buffer;
unsigned long n;
while (len > 0)
{
n = MIN (len, (16 - ctx->curlen));
memcpy (ctx->buf + ctx->curlen, in, (size_t) n);
ctx->curlen += n;
in += n;
len -= n;
/* is 16 bytes full? */
if (ctx->curlen == 16)
{
md2_compress (ctx);
md2_update_chksum (ctx);
ctx->curlen = 0;
}
}
}
static const unsigned char PI_SUBST[256] = {
41, 46, 67, 201, 162, 216, 124, 1, 61, 54, 84, 161, 236, 240, 6,
19, 98, 167, 5, 243, 192, 199, 115, 140, 152, 147, 43, 217, 188,
76, 130, 202, 30, 155, 87, 60, 253, 212, 224, 22, 103, 66, 111, 24,
138, 23, 229, 18, 190, 78, 196, 214, 218, 158, 222, 73, 160, 251,
245, 142, 187, 47, 238, 122, 169, 104, 121, 145, 21, 178, 7, 63,
148, 194, 16, 137, 11, 34, 95, 33, 128, 127, 93, 154, 90, 144, 50,
39, 53, 62, 204, 231, 191, 247, 151, 3, 255, 25, 48, 179, 72, 165,
181, 209, 215, 94, 146, 42, 172, 86, 170, 198, 79, 184, 56, 210,
150, 164, 125, 182, 118, 252, 107, 226, 156, 116, 4, 241, 69, 157,
112, 89, 100, 113, 135, 32, 134, 91, 207, 101, 230, 45, 168, 2, 27,
96, 37, 173, 174, 176, 185, 246, 28, 70, 97, 105, 52, 64, 126, 15,
85, 71, 163, 35, 221, 81, 175, 58, 195, 92, 249, 206, 186, 197,
234, 38, 44, 83, 13, 110, 133, 40, 132, 9, 211, 223, 205, 244, 65,
129, 77, 82, 106, 220, 55, 200, 108, 193, 171, 250, 36, 225, 123,
8, 12, 189, 177, 74, 120, 136, 149, 139, 227, 99, 232, 109, 233,
203, 213, 254, 59, 0, 29, 57, 242, 239, 183, 14, 102, 88, 208, 228,
166, 119, 114, 248, 235, 117, 75, 10, 49, 68, 80, 180, 143, 237,
31, 26, 219, 153, 141, 51, 159, 17, 131, 20
};
/* adds 16 bytes to the checksum */
static void
md2_update_chksum (struct md2_ctx *ctx)
{
int j;
unsigned char L;
L = ctx->chksum[15];
for (j = 0; j < 16; j++)
{
/* caution, the RFC says its "C[j] = S[M[i*16+j] xor L]" but the
reference source code [and test vectors] say otherwise. */
L = (ctx->chksum[j] ^= PI_SUBST[(int) (ctx->buf[j] ^ L)] & 255);
}
}
static void
md2_compress (struct md2_ctx *ctx)
{
size_t j, k;
unsigned char t;
/* copy block */
for (j = 0; j < 16; j++)
{
ctx->X[16 + j] = ctx->buf[j];
ctx->X[32 + j] = ctx->X[j] ^ ctx->X[16 + j];
}
t = (unsigned char) 0;
/* do 18 rounds */
for (j = 0; j < 18; j++)
{
for (k = 0; k < 48; k++)
{
t = (ctx->X[k] ^= PI_SUBST[(int) (t & 255)]);
}
t = (t + (unsigned char) j) & 255;
}
}
/* Process LEN bytes of BUFFER, accumulating context into CTX. */
void
md2_process_block (const void *buffer, size_t len, struct md2_ctx *ctx)
{
md2_process_bytes (buffer, len, ctx);
}
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