fips_dsa_sign.c
/* fips_dsa_sign.c */
/*
* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL project
* 2007.
*/
/* ====================================================================
* Copyright (c) 2007 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* licensing@OpenSSL.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com).
*
*/
#include <string.h>
#include <openssl/evp.h>
#include <openssl/dsa.h>
#include <openssl/err.h>
#include <openssl/sha.h>
#include <openssl/bn.h>
#ifdef OPENSSL_FIPS
/*
* FIPS versions of DSA_sign() and DSA_verify(). These include a tiny ASN1
* encoder/decoder to handle the specific case of a DSA signature.
*/
# if 0
int FIPS_dsa_size(DSA *r)
{
int ilen;
ilen = BN_num_bytes(r->q);
if (ilen > 20)
return -1;
/* If MSB set need padding byte */
ilen++;
/*
* Also need 2 bytes INTEGER header for r and s plus 2 bytes SEQUENCE
* header making 6 in total.
*/
return ilen * 2 + 6;
}
# endif
/*
* Tiny ASN1 encoder for DSA_SIG structure. We can assume r, s smaller than
* 0x80 octets as by the DSA standards they will be less than 2^160
*/
int FIPS_dsa_sig_encode(unsigned char *out, DSA_SIG *sig)
{
int rlen, slen, rpad, spad, seqlen;
rlen = BN_num_bytes(sig->r);
if (rlen > 20)
return -1;
if (BN_num_bits(sig->r) & 0x7)
rpad = 0;
else
rpad = 1;
slen = BN_num_bytes(sig->s);
if (slen > 20)
return -1;
if (BN_num_bits(sig->s) & 0x7)
spad = 0;
else
spad = 1;
/* Length of SEQUENCE, (1 tag + 1 len octet) * 2 + content octets */
seqlen = rlen + rpad + slen + spad + 4;
/* Actual encoded length: include SEQUENCE header */
if (!out)
return seqlen + 2;
/* Output SEQUENCE header */
*out++ = V_ASN1_SEQUENCE | V_ASN1_CONSTRUCTED;
*out++ = (unsigned char)seqlen;
/* Output r */
*out++ = V_ASN1_INTEGER;
*out++ = (unsigned char)(rlen + rpad);
if (rpad)
*out++ = 0;
BN_bn2bin(sig->r, out);
out += rlen;
/* Output s */
*out++ = V_ASN1_INTEGER;
*out++ = (unsigned char)(slen + spad);
if (spad)
*out++ = 0;
BN_bn2bin(sig->s, out);
return seqlen + 2;
}
/* Companion DSA_SIG decoder */
int FIPS_dsa_sig_decode(DSA_SIG *sig, const unsigned char *in, int inlen)
{
int seqlen, rlen, slen;
const unsigned char *rbin;
/* Sanity check */
/* Need SEQUENCE tag */
if (*in++ != (V_ASN1_SEQUENCE | V_ASN1_CONSTRUCTED))
return 0;
/* Get length octet */
seqlen = *in++;
/* Check sensible length value */
if (seqlen < 4 || seqlen > 0x7F)
return 0;
/* Check INTEGER tag */
if (*in++ != V_ASN1_INTEGER)
return 0;
rlen = *in++;
seqlen -= 2 + rlen;
/* Check sensible seqlen value */
if (seqlen < 2)
return 0;
rbin = in;
in += rlen;
/* Check INTEGER tag */
if (*in++ != V_ASN1_INTEGER)
return 0;
slen = *in++;
/*
* Remaining bytes of SEQUENCE should exactly match encoding of s
*/
if (seqlen != (slen + 2))
return 0;
if (!sig->r && !(sig->r = BN_new()))
return 0;
if (!sig->s && !(sig->s = BN_new()))
return 0;
if (!BN_bin2bn(rbin, rlen, sig->r))
return 0;
if (!BN_bin2bn(in, slen, sig->s))
return 0;
return 1;
}
static int fips_dsa_sign(int type, const unsigned char *x, int y,
unsigned char *sig, unsigned int *siglen,
EVP_MD_SVCTX * sv)
{
DSA *dsa = sv->key;
unsigned char dig[EVP_MAX_MD_SIZE];
unsigned int dlen;
DSA_SIG *s;
EVP_DigestFinal_ex(sv->mctx, dig, &dlen);
s = dsa->meth->dsa_do_sign(dig, dlen, dsa);
OPENSSL_cleanse(dig, dlen);
if (s == NULL) {
*siglen = 0;
return 0;
}
*siglen = FIPS_dsa_sig_encode(sig, s);
DSA_SIG_free(s);
if (*siglen < 0)
return 0;
return 1;
}
static int fips_dsa_verify(int type, const unsigned char *x, int y,
const unsigned char *sigbuf, unsigned int siglen,
EVP_MD_SVCTX * sv)
{
DSA *dsa = sv->key;
DSA_SIG *s;
int ret = -1;
unsigned char dig[EVP_MAX_MD_SIZE];
unsigned int dlen;
s = DSA_SIG_new();
if (s == NULL)
return ret;
if (!FIPS_dsa_sig_decode(s, sigbuf, siglen))
goto err;
EVP_DigestFinal_ex(sv->mctx, dig, &dlen);
ret = dsa->meth->dsa_do_verify(dig, dlen, s, dsa);
OPENSSL_cleanse(dig, dlen);
err:
DSA_SIG_free(s);
return ret;
}
static int init(EVP_MD_CTX *ctx)
{
return SHA1_Init(ctx->md_data);
}
static int update(EVP_MD_CTX *ctx, const void *data, size_t count)
{
return SHA1_Update(ctx->md_data, data, count);
}
static int final(EVP_MD_CTX *ctx, unsigned char *md)
{
return SHA1_Final(md, ctx->md_data);
}
static const EVP_MD dss1_md = {
NID_dsa,
NID_dsaWithSHA1,
SHA_DIGEST_LENGTH,
EVP_MD_FLAG_FIPS | EVP_MD_FLAG_SVCTX,
init,
update,
final,
NULL,
NULL,
(evp_sign_method *) fips_dsa_sign,
(evp_verify_method *) fips_dsa_verify,
{EVP_PKEY_DSA, EVP_PKEY_DSA2, EVP_PKEY_DSA3, EVP_PKEY_DSA4, 0},
SHA_CBLOCK,
sizeof(EVP_MD *) + sizeof(SHA_CTX),
};
const EVP_MD *EVP_dss1(void)
{
return (&dss1_md);
}
#endif
