[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 1.15 2002/06/23 03:30:17 deraadt 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;
	const 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 %u %u", 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;
	const 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 %u != 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"
d6133f43	26	RCSID("$OpenBSD: ssh-dss.c,v 1.15 2002/06/23 03:30:17 deraadt 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
d6133f43	43	ssh_dss_sign(Key key, u_char sigp, u_int lenp,
c66f9d0e	44	u_char *data, u_int datalen)
4f8c6159	45	{
4f8c6159	46	DSA_SIG *sig;
714954dc	47	const EVP_MD *evp_md = EVP_sha1();
4f8c6159	48	EVP_MD_CTX md;
087dea86	49	u_char *ret, digest[EVP_MAX_MD_SIZE], sigblob[SIGBLOB_LEN];
d87596b0	50	u_int rlen, slen, len, dlen;
4f8c6159	51	Buffer b;
	52
	53	if (key == NULL \|\| key->type != KEY_DSA \|\| key->dsa == NULL) {
fa08c86b	54	error("ssh_dss_sign: no DSA key");
4f8c6159	55	return -1;
4f8c6159	56	}
4f8c6159	57	EVP_DigestInit(&md, evp_md);
a306f2dd	58	EVP_DigestUpdate(&md, data, datalen);
087dea86	59	EVP_DigestFinal(&md, digest, &dlen);
4f8c6159	60
42f11eb2	61	sig = DSA_do_sign(digest, dlen, key->dsa);
087dea86	62	memset(digest, 'd', sizeof(digest));
d87596b0	63
d87596b0	64	if (sig == NULL) {
	65	error("ssh_dss_sign: sign failed");
	66	return -1;
	67	}
4f8c6159	68
	69	rlen = BN_num_bytes(sig->r);
	70	slen = BN_num_bytes(sig->s);
	71	if (rlen > INTBLOB_LEN \|\| slen > INTBLOB_LEN) {
d6133f43	72	error("bad sig size %u %u", rlen, slen);
4f8c6159	73	DSA_SIG_free(sig);
	74	return -1;
	75	}
4f8c6159	76	memset(sigblob, 0, SIGBLOB_LEN);
	77	BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
	78	BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
	79	DSA_SIG_free(sig);
	80
d0c832f3	81	if (datafellows & SSH_BUG_SIGBLOB) {
4f8c6159	82	ret = xmalloc(SIGBLOB_LEN);
	83	memcpy(ret, sigblob, SIGBLOB_LEN);
	84	if (lenp != NULL)
	85	*lenp = SIGBLOB_LEN;
	86	if (sigp != NULL)
	87	*sigp = ret;
	88	} else {
	89	/* ietf-drafts */
	90	buffer_init(&b);
fa08c86b	91	buffer_put_cstring(&b, "ssh-dss");
4f8c6159	92	buffer_put_string(&b, sigblob, SIGBLOB_LEN);
	93	len = buffer_len(&b);
	94	ret = xmalloc(len);
	95	memcpy(ret, buffer_ptr(&b), len);
	96	buffer_free(&b);
	97	if (lenp != NULL)
	98	*lenp = len;
	99	if (sigp != NULL)
	100	*sigp = ret;
	101	}
	102	return 0;
	103	}
	104	int
d6133f43	105	ssh_dss_verify(Key key, u_char signature, u_int signaturelen,
c66f9d0e	106	u_char *data, u_int datalen)
4f8c6159	107	{
4f8c6159	108	DSA_SIG *sig;
714954dc	109	const EVP_MD *evp_md = EVP_sha1();
4f8c6159	110	EVP_MD_CTX md;
087dea86	111	u_char digest[EVP_MAX_MD_SIZE], *sigblob;
1e3b8b07	112	u_int len, dlen;
d87596b0	113	int rlen, ret;
d87596b0	114	Buffer b;
4f8c6159	115
4f8c6159	116	if (key == NULL \|\| key->type != KEY_DSA \|\| key->dsa == NULL) {
fa08c86b	117	error("ssh_dss_verify: no DSA key");
4f8c6159	118	return -1;
	119	}
	120
4f8c6159	121	/* fetch signature */
d0c832f3	122	if (datafellows & SSH_BUG_SIGBLOB) {
4f8c6159	123	sigblob = signature;
	124	len = signaturelen;
	125	} else {
	126	/* ietf-drafts */
74fc9186	127	char *ktype;
4f8c6159	128	buffer_init(&b);
cf54363d	129	buffer_append(&b, signature, signaturelen);
4f8c6159	130	ktype = buffer_get_string(&b, NULL);
fa08c86b	131	if (strcmp("ssh-dss", ktype) != 0) {
fa08c86b	132	error("ssh_dss_verify: cannot handle type %s", ktype);
74fc9186	133	buffer_free(&b);
abc4e9a7	134	xfree(ktype);
74fc9186	135	return -1;
74fc9186	136	}
abc4e9a7	137	xfree(ktype);
cf54363d	138	sigblob = buffer_get_string(&b, &len);
4f8c6159	139	rlen = buffer_len(&b);
abc4e9a7	140	buffer_free(&b);
6aacefa7	141	if (rlen != 0) {
abc4e9a7	142	error("ssh_dss_verify: "
	143	"remaining bytes in signature %d", rlen);
	144	xfree(sigblob);
74fc9186	145	return -1;
74fc9186	146	}
4f8c6159	147	}
	148
	149	if (len != SIGBLOB_LEN) {
d6133f43	150	fatal("bad sigbloblen %u != SIGBLOB_LEN", len);
4f8c6159	151	}
	152
	153	/* parse signature */
b775c6f2	154	if ((sig = DSA_SIG_new()) == NULL)
	155	fatal("ssh_dss_verify: DSA_SIG_new failed");
	156	if ((sig->r = BN_new()) == NULL)
	157	fatal("ssh_dss_verify: BN_new failed");
	158	if ((sig->s = BN_new()) == NULL)
	159	fatal("ssh_dss_verify: BN_new failed");
4f8c6159	160	BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
4f8c6159	161	BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
d0c832f3	162
d0c832f3	163	if (!(datafellows & SSH_BUG_SIGBLOB)) {
4f8c6159	164	memset(sigblob, 0, len);
	165	xfree(sigblob);
	166	}
2b87da3b	167
a306f2dd	168	/* sha1 the data */
4f8c6159	169	EVP_DigestInit(&md, evp_md);
a306f2dd	170	EVP_DigestUpdate(&md, data, datalen);
087dea86	171	EVP_DigestFinal(&md, digest, &dlen);
4f8c6159	172
fa08c86b	173	ret = DSA_do_verify(digest, dlen, sig, key->dsa);
087dea86	174	memset(digest, 'd', sizeof(digest));
4f8c6159	175
4f8c6159	176	DSA_SIG_free(sig);
4f8c6159	177
d87596b0	178	debug("ssh_dss_verify: signature %s",
d87596b0	179	ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");
4f8c6159	180	return ret;
4f8c6159	181	}