[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 1.11 2001/12/27 18:22:16 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, int *lenp,
    u_char *data, int datalen)
{
	DSA_SIG *sig;
	EVP_MD *evp_md = EVP_sha1();
	EVP_MD_CTX md;
	u_char *digest, *ret, 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;
	}
	dlen = evp_md->md_size;
	digest = xmalloc(dlen);
	EVP_DigestInit(&md, evp_md);
	EVP_DigestUpdate(&md, data, datalen);
	EVP_DigestFinal(&md, digest, NULL);

	sig = DSA_do_sign(digest, dlen, key->dsa);

	memset(digest, 0, dlen);
	xfree(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, int signaturelen,
    u_char *data, int datalen)
{
	DSA_SIG *sig;
	EVP_MD *evp_md = EVP_sha1();
	EVP_MD_CTX md;
	u_char *digest, *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 */
	dlen = evp_md->md_size;
	digest = xmalloc(dlen);
	EVP_DigestInit(&md, evp_md);
	EVP_DigestUpdate(&md, data, datalen);
	EVP_DigestFinal(&md, digest, NULL);

	ret = DSA_do_verify(digest, dlen, sig, key->dsa);

	memset(digest, 0, dlen);
	xfree(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"
b775c6f2	26	RCSID("$OpenBSD: ssh-dss.c,v 1.11 2001/12/27 18:22:16 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,
1e3b8b07	45	u_char *sigp, int lenp,
1e3b8b07	46	u_char *data, int datalen)
4f8c6159	47	{
4f8c6159	48	DSA_SIG *sig;
	49	EVP_MD *evp_md = EVP_sha1();
	50	EVP_MD_CTX md;
d87596b0	51	u_char digest, ret, 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	}
42f11eb2	59	dlen = evp_md->md_size;
42f11eb2	60	digest = xmalloc(dlen);
4f8c6159	61	EVP_DigestInit(&md, evp_md);
a306f2dd	62	EVP_DigestUpdate(&md, data, datalen);
4f8c6159	63	EVP_DigestFinal(&md, digest, NULL);
4f8c6159	64
42f11eb2	65	sig = DSA_do_sign(digest, dlen, key->dsa);
d87596b0	66
42f11eb2	67	memset(digest, 0, dlen);
42f11eb2	68	xfree(digest);
d87596b0	69	if (sig == NULL) {
	70	error("ssh_dss_sign: sign failed");
	71	return -1;
	72	}
4f8c6159	73
	74	rlen = BN_num_bytes(sig->r);
	75	slen = BN_num_bytes(sig->s);
	76	if (rlen > INTBLOB_LEN \|\| slen > INTBLOB_LEN) {
	77	error("bad sig size %d %d", rlen, slen);
	78	DSA_SIG_free(sig);
	79	return -1;
	80	}
4f8c6159	81	memset(sigblob, 0, SIGBLOB_LEN);
	82	BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
	83	BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
	84	DSA_SIG_free(sig);
	85
d0c832f3	86	if (datafellows & SSH_BUG_SIGBLOB) {
4f8c6159	87	ret = xmalloc(SIGBLOB_LEN);
	88	memcpy(ret, sigblob, SIGBLOB_LEN);
	89	if (lenp != NULL)
	90	*lenp = SIGBLOB_LEN;
	91	if (sigp != NULL)
	92	*sigp = ret;
	93	} else {
	94	/* ietf-drafts */
	95	buffer_init(&b);
fa08c86b	96	buffer_put_cstring(&b, "ssh-dss");
4f8c6159	97	buffer_put_string(&b, sigblob, SIGBLOB_LEN);
	98	len = buffer_len(&b);
	99	ret = xmalloc(len);
	100	memcpy(ret, buffer_ptr(&b), len);
	101	buffer_free(&b);
	102	if (lenp != NULL)
	103	*lenp = len;
	104	if (sigp != NULL)
	105	*sigp = ret;
	106	}
	107	return 0;
	108	}
	109	int
fa08c86b	110	ssh_dss_verify(
4f8c6159	111	Key *key,
1e3b8b07	112	u_char *signature, int signaturelen,
1e3b8b07	113	u_char *data, int datalen)
4f8c6159	114	{
4f8c6159	115	DSA_SIG *sig;
	116	EVP_MD *evp_md = EVP_sha1();
	117	EVP_MD_CTX md;
d87596b0	118	u_char digest, sigblob;
1e3b8b07	119	u_int len, dlen;
d87596b0	120	int rlen, ret;
d87596b0	121	Buffer b;
4f8c6159	122
4f8c6159	123	if (key == NULL \|\| key->type != KEY_DSA \|\| key->dsa == NULL) {
fa08c86b	124	error("ssh_dss_verify: no DSA key");
4f8c6159	125	return -1;
	126	}
	127
4f8c6159	128	/* fetch signature */
d0c832f3	129	if (datafellows & SSH_BUG_SIGBLOB) {
4f8c6159	130	sigblob = signature;
	131	len = signaturelen;
	132	} else {
	133	/* ietf-drafts */
74fc9186	134	char *ktype;
4f8c6159	135	buffer_init(&b);
cf54363d	136	buffer_append(&b, signature, signaturelen);
4f8c6159	137	ktype = buffer_get_string(&b, NULL);
fa08c86b	138	if (strcmp("ssh-dss", ktype) != 0) {
fa08c86b	139	error("ssh_dss_verify: cannot handle type %s", ktype);
74fc9186	140	buffer_free(&b);
abc4e9a7	141	xfree(ktype);
74fc9186	142	return -1;
74fc9186	143	}
abc4e9a7	144	xfree(ktype);
cf54363d	145	sigblob = buffer_get_string(&b, &len);
4f8c6159	146	rlen = buffer_len(&b);
abc4e9a7	147	buffer_free(&b);
6aacefa7	148	if (rlen != 0) {
abc4e9a7	149	error("ssh_dss_verify: "
	150	"remaining bytes in signature %d", rlen);
	151	xfree(sigblob);
74fc9186	152	return -1;
74fc9186	153	}
4f8c6159	154	}
	155
	156	if (len != SIGBLOB_LEN) {
	157	fatal("bad sigbloblen %d != SIGBLOB_LEN", len);
	158	}
	159
	160	/* parse signature */
b775c6f2	161	if ((sig = DSA_SIG_new()) == NULL)
	162	fatal("ssh_dss_verify: DSA_SIG_new failed");
	163	if ((sig->r = BN_new()) == NULL)
	164	fatal("ssh_dss_verify: BN_new failed");
	165	if ((sig->s = BN_new()) == NULL)
	166	fatal("ssh_dss_verify: BN_new failed");
4f8c6159	167	BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
4f8c6159	168	BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
d0c832f3	169
d0c832f3	170	if (!(datafellows & SSH_BUG_SIGBLOB)) {
4f8c6159	171	memset(sigblob, 0, len);
	172	xfree(sigblob);
	173	}
2b87da3b	174
a306f2dd	175	/* sha1 the data */
fa08c86b	176	dlen = evp_md->md_size;
fa08c86b	177	digest = xmalloc(dlen);
4f8c6159	178	EVP_DigestInit(&md, evp_md);
a306f2dd	179	EVP_DigestUpdate(&md, data, datalen);
4f8c6159	180	EVP_DigestFinal(&md, digest, NULL);
4f8c6159	181
fa08c86b	182	ret = DSA_do_verify(digest, dlen, sig, key->dsa);
4f8c6159	183
fa08c86b	184	memset(digest, 0, dlen);
4f8c6159	185	xfree(digest);
	186	DSA_SIG_free(sig);
	187
d87596b0	188	debug("ssh_dss_verify: signature %s",
d87596b0	189	ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");
4f8c6159	190	return ret;
4f8c6159	191	}