[openssh.git] / ssh-dss.c

/*
 * Copyright (c) 2000 Markus Friedl.  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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 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 AUTHOR 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.
 */

#include "includes.h"
RCSID("$OpenBSD: ssh-dss.c,v 1.13 2002/02/24 19:14:59 markus Exp $");

#include <openssl/bn.h>
#include <openssl/evp.h>

#include "xmalloc.h"
#include "buffer.h"
#include "bufaux.h"
#include "compat.h"
#include "log.h"
#include "key.h"
#include "ssh-dss.h"

#define INTBLOB_LEN	20
#define SIGBLOB_LEN	(2*INTBLOB_LEN)

int
ssh_dss_sign(
    Key *key,
    u_char **sigp, u_int *lenp,
    u_char *data, u_int datalen)
{
	DSA_SIG *sig;
	EVP_MD *evp_md = EVP_sha1();
	EVP_MD_CTX md;
	u_char *ret, digest[EVP_MAX_MD_SIZE], sigblob[SIGBLOB_LEN];
	u_int rlen, slen, len, dlen;
	Buffer b;

	if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
		error("ssh_dss_sign: no DSA key");
		return -1;
	}
	EVP_DigestInit(&md, evp_md);
	EVP_DigestUpdate(&md, data, datalen);
	EVP_DigestFinal(&md, digest, &dlen);

	sig = DSA_do_sign(digest, dlen, key->dsa);
	memset(digest, 'd', sizeof(digest));

	if (sig == NULL) {
		error("ssh_dss_sign: sign failed");
		return -1;
	}

	rlen = BN_num_bytes(sig->r);
	slen = BN_num_bytes(sig->s);
	if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
		error("bad sig size %d %d", rlen, slen);
		DSA_SIG_free(sig);
		return -1;
	}
	memset(sigblob, 0, SIGBLOB_LEN);
	BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
	BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
	DSA_SIG_free(sig);

	if (datafellows & SSH_BUG_SIGBLOB) {
		ret = xmalloc(SIGBLOB_LEN);
		memcpy(ret, sigblob, SIGBLOB_LEN);
		if (lenp != NULL)
			*lenp = SIGBLOB_LEN;
		if (sigp != NULL)
			*sigp = ret;
	} else {
		/* ietf-drafts */
		buffer_init(&b);
		buffer_put_cstring(&b, "ssh-dss");
		buffer_put_string(&b, sigblob, SIGBLOB_LEN);
		len = buffer_len(&b);
		ret = xmalloc(len);
		memcpy(ret, buffer_ptr(&b), len);
		buffer_free(&b);
		if (lenp != NULL)
			*lenp = len;
		if (sigp != NULL)
			*sigp = ret;
	}
	return 0;
}
int
ssh_dss_verify(
    Key *key,
    u_char *signature, u_int signaturelen,
    u_char *data, u_int datalen)
{
	DSA_SIG *sig;
	EVP_MD *evp_md = EVP_sha1();
	EVP_MD_CTX md;
	u_char digest[EVP_MAX_MD_SIZE], *sigblob;
	u_int len, dlen;
	int rlen, ret;
	Buffer b;

	if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
		error("ssh_dss_verify: no DSA key");
		return -1;
	}

	/* fetch signature */
	if (datafellows & SSH_BUG_SIGBLOB) {
		sigblob = signature;
		len = signaturelen;
	} else {
		/* ietf-drafts */
		char *ktype;
		buffer_init(&b);
		buffer_append(&b, signature, signaturelen);
		ktype = buffer_get_string(&b, NULL);
		if (strcmp("ssh-dss", ktype) != 0) {
			error("ssh_dss_verify: cannot handle type %s", ktype);
			buffer_free(&b);
			xfree(ktype);
			return -1;
		}
		xfree(ktype);
		sigblob = buffer_get_string(&b, &len);
		rlen = buffer_len(&b);
		buffer_free(&b);
		if (rlen != 0) {
			error("ssh_dss_verify: "
			    "remaining bytes in signature %d", rlen);
			xfree(sigblob);
			return -1;
		}
	}

	if (len != SIGBLOB_LEN) {
		fatal("bad sigbloblen %d != SIGBLOB_LEN", len);
	}

	/* parse signature */
	if ((sig = DSA_SIG_new()) == NULL)
		fatal("ssh_dss_verify: DSA_SIG_new failed");
	if ((sig->r = BN_new()) == NULL)
		fatal("ssh_dss_verify: BN_new failed");
	if ((sig->s = BN_new()) == NULL)
		fatal("ssh_dss_verify: BN_new failed");
	BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
	BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);

	if (!(datafellows & SSH_BUG_SIGBLOB)) {
		memset(sigblob, 0, len);
		xfree(sigblob);
	}

	/* sha1 the data */
	EVP_DigestInit(&md, evp_md);
	EVP_DigestUpdate(&md, data, datalen);
	EVP_DigestFinal(&md, digest, &dlen);

	ret = DSA_do_verify(digest, dlen, sig, key->dsa);
	memset(digest, 'd', sizeof(digest));

	DSA_SIG_free(sig);

	debug("ssh_dss_verify: signature %s",
	    ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");
	return ret;
}
Commit	Line	Data
4f8c6159	1	/*
	2	* Copyright (c) 2000 Markus Friedl. All rights reserved.
	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	* 1. Redistributions of source code must retain the above copyright
	8	* notice, this list of conditions and the following disclaimer.
	9	* 2. Redistributions in binary form must reproduce the above copyright
	10	* notice, this list of conditions and the following disclaimer in the
	11	* documentation and/or other materials provided with the distribution.
4f8c6159	12	*
	13	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	14	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	15	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	16	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	17	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	18	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	19	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	20	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	21	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	22	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	23	*/
	24
	25	#include "includes.h"
c66f9d0e	26	RCSID("$OpenBSD: ssh-dss.c,v 1.13 2002/02/24 19:14:59 markus Exp $");
42f11eb2	27
	28	#include <openssl/bn.h>
	29	#include <openssl/evp.h>
4f8c6159	30
4f8c6159	31	#include "xmalloc.h"
	32	#include "buffer.h"
	33	#include "bufaux.h"
	34	#include "compat.h"
42f11eb2	35	#include "log.h"
4f8c6159	36	#include "key.h"
5ca51e19	37	#include "ssh-dss.h"
4f8c6159	38
	39	#define INTBLOB_LEN 20
	40	#define SIGBLOB_LEN (2*INTBLOB_LEN)
	41
4f8c6159	42	int
fa08c86b	43	ssh_dss_sign(
4f8c6159	44	Key *key,
c66f9d0e	45	u_char *sigp, u_int lenp,
c66f9d0e	46	u_char *data, u_int datalen)
4f8c6159	47	{
4f8c6159	48	DSA_SIG *sig;
	49	EVP_MD *evp_md = EVP_sha1();
	50	EVP_MD_CTX md;
087dea86	51	u_char *ret, digest[EVP_MAX_MD_SIZE], sigblob[SIGBLOB_LEN];
d87596b0	52	u_int rlen, slen, len, dlen;
4f8c6159	53	Buffer b;
	54
	55	if (key == NULL \|\| key->type != KEY_DSA \|\| key->dsa == NULL) {
fa08c86b	56	error("ssh_dss_sign: no DSA key");
4f8c6159	57	return -1;
4f8c6159	58	}
4f8c6159	59	EVP_DigestInit(&md, evp_md);
a306f2dd	60	EVP_DigestUpdate(&md, data, datalen);
087dea86	61	EVP_DigestFinal(&md, digest, &dlen);
4f8c6159	62
42f11eb2	63	sig = DSA_do_sign(digest, dlen, key->dsa);
087dea86	64	memset(digest, 'd', sizeof(digest));
d87596b0	65
d87596b0	66	if (sig == NULL) {
	67	error("ssh_dss_sign: sign failed");
	68	return -1;
	69	}
4f8c6159	70
	71	rlen = BN_num_bytes(sig->r);
	72	slen = BN_num_bytes(sig->s);
	73	if (rlen > INTBLOB_LEN \|\| slen > INTBLOB_LEN) {
	74	error("bad sig size %d %d", rlen, slen);
	75	DSA_SIG_free(sig);
	76	return -1;
	77	}
4f8c6159	78	memset(sigblob, 0, SIGBLOB_LEN);
	79	BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
	80	BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
	81	DSA_SIG_free(sig);
	82
d0c832f3	83	if (datafellows & SSH_BUG_SIGBLOB) {
4f8c6159	84	ret = xmalloc(SIGBLOB_LEN);
	85	memcpy(ret, sigblob, SIGBLOB_LEN);
	86	if (lenp != NULL)
	87	*lenp = SIGBLOB_LEN;
	88	if (sigp != NULL)
	89	*sigp = ret;
	90	} else {
	91	/* ietf-drafts */
	92	buffer_init(&b);
fa08c86b	93	buffer_put_cstring(&b, "ssh-dss");
4f8c6159	94	buffer_put_string(&b, sigblob, SIGBLOB_LEN);
	95	len = buffer_len(&b);
	96	ret = xmalloc(len);
	97	memcpy(ret, buffer_ptr(&b), len);
	98	buffer_free(&b);
	99	if (lenp != NULL)
	100	*lenp = len;
	101	if (sigp != NULL)
	102	*sigp = ret;
	103	}
	104	return 0;
	105	}
	106	int
fa08c86b	107	ssh_dss_verify(
4f8c6159	108	Key *key,
c66f9d0e	109	u_char *signature, u_int signaturelen,
c66f9d0e	110	u_char *data, u_int datalen)
4f8c6159	111	{
4f8c6159	112	DSA_SIG *sig;
	113	EVP_MD *evp_md = EVP_sha1();
	114	EVP_MD_CTX md;
087dea86	115	u_char digest[EVP_MAX_MD_SIZE], *sigblob;
1e3b8b07	116	u_int len, dlen;
d87596b0	117	int rlen, ret;
d87596b0	118	Buffer b;
4f8c6159	119
4f8c6159	120	if (key == NULL \|\| key->type != KEY_DSA \|\| key->dsa == NULL) {
fa08c86b	121	error("ssh_dss_verify: no DSA key");
4f8c6159	122	return -1;
	123	}
	124
4f8c6159	125	/* fetch signature */
d0c832f3	126	if (datafellows & SSH_BUG_SIGBLOB) {
4f8c6159	127	sigblob = signature;
	128	len = signaturelen;
	129	} else {
	130	/* ietf-drafts */
74fc9186	131	char *ktype;
4f8c6159	132	buffer_init(&b);
cf54363d	133	buffer_append(&b, signature, signaturelen);
4f8c6159	134	ktype = buffer_get_string(&b, NULL);
fa08c86b	135	if (strcmp("ssh-dss", ktype) != 0) {
fa08c86b	136	error("ssh_dss_verify: cannot handle type %s", ktype);
74fc9186	137	buffer_free(&b);
abc4e9a7	138	xfree(ktype);
74fc9186	139	return -1;
74fc9186	140	}
abc4e9a7	141	xfree(ktype);
cf54363d	142	sigblob = buffer_get_string(&b, &len);
4f8c6159	143	rlen = buffer_len(&b);
abc4e9a7	144	buffer_free(&b);
6aacefa7	145	if (rlen != 0) {
abc4e9a7	146	error("ssh_dss_verify: "
	147	"remaining bytes in signature %d", rlen);
	148	xfree(sigblob);
74fc9186	149	return -1;
74fc9186	150	}
4f8c6159	151	}
	152
	153	if (len != SIGBLOB_LEN) {
	154	fatal("bad sigbloblen %d != SIGBLOB_LEN", len);
	155	}
	156
	157	/* parse signature */
b775c6f2	158	if ((sig = DSA_SIG_new()) == NULL)
	159	fatal("ssh_dss_verify: DSA_SIG_new failed");
	160	if ((sig->r = BN_new()) == NULL)
	161	fatal("ssh_dss_verify: BN_new failed");
	162	if ((sig->s = BN_new()) == NULL)
	163	fatal("ssh_dss_verify: BN_new failed");
4f8c6159	164	BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
4f8c6159	165	BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
d0c832f3	166
d0c832f3	167	if (!(datafellows & SSH_BUG_SIGBLOB)) {
4f8c6159	168	memset(sigblob, 0, len);
	169	xfree(sigblob);
	170	}
2b87da3b	171
a306f2dd	172	/* sha1 the data */
4f8c6159	173	EVP_DigestInit(&md, evp_md);
a306f2dd	174	EVP_DigestUpdate(&md, data, datalen);
087dea86	175	EVP_DigestFinal(&md, digest, &dlen);
4f8c6159	176
fa08c86b	177	ret = DSA_do_verify(digest, dlen, sig, key->dsa);
087dea86	178	memset(digest, 'd', sizeof(digest));
4f8c6159	179
4f8c6159	180	DSA_SIG_free(sig);
4f8c6159	181
d87596b0	182	debug("ssh_dss_verify: signature %s",
d87596b0	183	ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");
4f8c6159	184	return ret;
4f8c6159	185	}