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/* hash-common.c - Common code for hash algorithms
* Copyright (C) 2008 Free Software Foundation, Inc.
*
* This file is part of Libgcrypt.
*
* Libgcrypt 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.
*
* Libgcrypt 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
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef HAVE_STDINT_H
# include <stdint.h>
#endif
#include "g10lib.h"
#include "bufhelp.h"
#include "hash-common.h"
/* Run a selftest for hash algorithm ALGO. If the resulting digest
matches EXPECT/EXPECTLEN and everything else is fine as well,
return NULL. If an error occurs, return a static text string
describing the error.
DATAMODE controls what will be hashed according to this table:
0 - Hash the supplied DATA of DATALEN.
1 - Hash one million times a 'a'. DATA and DATALEN are ignored.
*/
const char *
_gcry_hash_selftest_check_one (int algo,
int datamode, const void *data, size_t datalen,
const void *expect, size_t expectlen)
{
const char *result = NULL;
gcry_error_t err = 0;
gcry_md_hd_t hd;
unsigned char *digest;
char aaa[1000];
int xof = 0;
if (_gcry_md_get_algo_dlen (algo) == 0)
xof = 1;
else if (_gcry_md_get_algo_dlen (algo) != expectlen)
return "digest size does not match expected size";
err = _gcry_md_open (&hd, algo, 0);
if (err)
return "gcry_md_open failed";
switch (datamode)
{
case 0:
_gcry_md_write (hd, data, datalen);
break;
case 1: /* Hash one million times an "a". */
{
int i;
/* Write in odd size chunks so that we test the buffering. */
memset (aaa, 'a', 1000);
for (i = 0; i < 1000; i++)
_gcry_md_write (hd, aaa, 1000);
}
break;
default:
result = "invalid DATAMODE";
}
if (!result)
{
if (!xof)
{
digest = _gcry_md_read (hd, algo);
if ( memcmp (digest, expect, expectlen) )
result = "digest mismatch";
}
else
{
gcry_assert(expectlen <= sizeof(aaa));
err = _gcry_md_extract (hd, algo, aaa, expectlen);
if (err)
result = "error extracting output from XOF";
else if ( memcmp (aaa, expect, expectlen) )
result = "digest mismatch";
}
}
_gcry_md_close (hd);
return result;
}
/* Common function to write a chunk of data to the transform function
of a hash algorithm. Note that the use of the term "block" does
not imply a fixed size block. Note that we explicitly allow to use
this function after the context has been finalized; the result does
not have any meaning but writing after finalize is sometimes
helpful to mitigate timing attacks. */
void
_gcry_md_block_write (void *context, const void *inbuf_arg, size_t inlen)
{
const unsigned char *inbuf = inbuf_arg;
gcry_md_block_ctx_t *hd = context;
unsigned int stack_burn = 0;
unsigned int nburn;
const unsigned int blocksize_shift = hd->blocksize_shift;
const unsigned int blocksize = 1 << blocksize_shift;
size_t inblocks;
size_t copylen;
if (sizeof(hd->buf) < blocksize)
BUG();
if (!hd->bwrite)
return;
if (hd->count > blocksize)
{
/* This happens only when gcry_md_write is called after final.
* Writing after final is used for mitigating timing attacks. */
hd->count = 0;
}
while (hd->count)
{
if (hd->count == blocksize) /* Flush the buffer. */
{
nburn = hd->bwrite (hd, hd->buf, 1);
stack_burn = nburn > stack_burn ? nburn : stack_burn;
hd->count = 0;
if (!++hd->nblocks)
hd->nblocks_high++;
}
else
{
copylen = inlen;
if (copylen > blocksize - hd->count)
copylen = blocksize - hd->count;
if (copylen == 0)
break;
buf_cpy (&hd->buf[hd->count], inbuf, copylen);
hd->count += copylen;
inbuf += copylen;
inlen -= copylen;
}
}
if (inlen == 0)
return;
if (inlen >= blocksize)
{
inblocks = inlen >> blocksize_shift;
nburn = hd->bwrite (hd, inbuf, inblocks);
stack_burn = nburn > stack_burn ? nburn : stack_burn;
hd->count = 0;
hd->nblocks_high += (hd->nblocks + inblocks < inblocks);
hd->nblocks += inblocks;
inlen -= inblocks << blocksize_shift;
inbuf += inblocks << blocksize_shift;
}
if (inlen)
{
buf_cpy (hd->buf, inbuf, inlen);
hd->count = inlen;
}
if (stack_burn > 0)
_gcry_burn_stack (stack_burn);
}