[gssapi-openssh.git] / openssh / 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 1.19 2003/11/10 16:23:41 jakob 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"

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

int
ssh_dss_sign(const Key *key, u_char **sigp, u_int *lenp,
    const 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[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) {
		if (lenp != NULL)
			*lenp = SIGBLOB_LEN;
		if (sigp != NULL) {
			*sigp = xmalloc(SIGBLOB_LEN);
			memcpy(*sigp, sigblob, SIGBLOB_LEN);
		}
	} else {
		/* ietf-drafts */
		buffer_init(&b);
		buffer_put_cstring(&b, "ssh-dss");
		buffer_put_string(&b, sigblob, SIGBLOB_LEN);
		len = buffer_len(&b);
		if (lenp != NULL)
			*lenp = len;
		if (sigp != NULL) {
			*sigp = xmalloc(len);
			memcpy(*sigp, buffer_ptr(&b), len);
		}
		buffer_free(&b);
	}
	return 0;
}
int
ssh_dss_verify(const Key *key, const u_char *signature, u_int signaturelen,
    const 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 = xmalloc(signaturelen);
		memcpy(sigblob, signature, signaturelen);
		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);

	/* clean up */
	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
3c0ef626	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.
	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"
12408a1b	26	RCSID("$OpenBSD: ssh-dss.c,v 1.19 2003/11/10 16:23:41 jakob Exp $");
3c0ef626	27
	28	#include <openssl/bn.h>
	29	#include <openssl/evp.h>
	30
	31	#include "xmalloc.h"
	32	#include "buffer.h"
	33	#include "bufaux.h"
	34	#include "compat.h"
	35	#include "log.h"
	36	#include "key.h"
3c0ef626	37
	38	#define INTBLOB_LEN 20
	39	#define SIGBLOB_LEN (2*INTBLOB_LEN)
	40
	41	int
12408a1b	42	ssh_dss_sign(const Key key, u_char sigp, u_int lenp,
12408a1b	43	const u_char *data, u_int datalen)
3c0ef626	44	{
3c0ef626	45	DSA_SIG *sig;
e9a17296	46	const EVP_MD *evp_md = EVP_sha1();
3c0ef626	47	EVP_MD_CTX md;
41b2f314	48	u_char digest[EVP_MAX_MD_SIZE], sigblob[SIGBLOB_LEN];
3c0ef626	49	u_int rlen, slen, len, dlen;
	50	Buffer b;
	51
	52	if (key == NULL \|\| key->type != KEY_DSA \|\| key->dsa == NULL) {
	53	error("ssh_dss_sign: no DSA key");
	54	return -1;
	55	}
3c0ef626	56	EVP_DigestInit(&md, evp_md);
3c0ef626	57	EVP_DigestUpdate(&md, data, datalen);
e9a17296	58	EVP_DigestFinal(&md, digest, &dlen);
3c0ef626	59
3c0ef626	60	sig = DSA_do_sign(digest, dlen, key->dsa);
e9a17296	61	memset(digest, 'd', sizeof(digest));
3c0ef626	62
3c0ef626	63	if (sig == NULL) {
	64	error("ssh_dss_sign: sign failed");
	65	return -1;
	66	}
	67
	68	rlen = BN_num_bytes(sig->r);
	69	slen = BN_num_bytes(sig->s);
	70	if (rlen > INTBLOB_LEN \|\| slen > INTBLOB_LEN) {
680cee3b	71	error("bad sig size %u %u", rlen, slen);
3c0ef626	72	DSA_SIG_free(sig);
	73	return -1;
	74	}
	75	memset(sigblob, 0, SIGBLOB_LEN);
	76	BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
	77	BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
	78	DSA_SIG_free(sig);
	79
	80	if (datafellows & SSH_BUG_SIGBLOB) {
3c0ef626	81	if (lenp != NULL)
3c0ef626	82	*lenp = SIGBLOB_LEN;
41b2f314	83	if (sigp != NULL) {
	84	*sigp = xmalloc(SIGBLOB_LEN);
	85	memcpy(*sigp, sigblob, SIGBLOB_LEN);
	86	}
3c0ef626	87	} else {
	88	/* ietf-drafts */
	89	buffer_init(&b);
	90	buffer_put_cstring(&b, "ssh-dss");
	91	buffer_put_string(&b, sigblob, SIGBLOB_LEN);
	92	len = buffer_len(&b);
3c0ef626	93	if (lenp != NULL)
3c0ef626	94	*lenp = len;
41b2f314	95	if (sigp != NULL) {
	96	*sigp = xmalloc(len);
	97	memcpy(*sigp, buffer_ptr(&b), len);
	98	}
	99	buffer_free(&b);
3c0ef626	100	}
	101	return 0;
	102	}
	103	int
12408a1b	104	ssh_dss_verify(const Key key, const u_char signature, u_int signaturelen,
12408a1b	105	const u_char *data, u_int datalen)
3c0ef626	106	{
3c0ef626	107	DSA_SIG *sig;
e9a17296	108	const EVP_MD *evp_md = EVP_sha1();
3c0ef626	109	EVP_MD_CTX md;
e9a17296	110	u_char digest[EVP_MAX_MD_SIZE], *sigblob;
3c0ef626	111	u_int len, dlen;
	112	int rlen, ret;
	113	Buffer b;
	114
	115	if (key == NULL \|\| key->type != KEY_DSA \|\| key->dsa == NULL) {
	116	error("ssh_dss_verify: no DSA key");
	117	return -1;
	118	}
	119
	120	/* fetch signature */
	121	if (datafellows & SSH_BUG_SIGBLOB) {
12408a1b	122	sigblob = xmalloc(signaturelen);
12408a1b	123	memcpy(sigblob, signature, signaturelen);
3c0ef626	124	len = signaturelen;
	125	} else {
	126	/* ietf-drafts */
	127	char *ktype;
	128	buffer_init(&b);
	129	buffer_append(&b, signature, signaturelen);
	130	ktype = buffer_get_string(&b, NULL);
	131	if (strcmp("ssh-dss", ktype) != 0) {
	132	error("ssh_dss_verify: cannot handle type %s", ktype);
	133	buffer_free(&b);
	134	xfree(ktype);
	135	return -1;
	136	}
	137	xfree(ktype);
	138	sigblob = buffer_get_string(&b, &len);
	139	rlen = buffer_len(&b);
	140	buffer_free(&b);
e9a17296	141	if (rlen != 0) {
3c0ef626	142	error("ssh_dss_verify: "
	143	"remaining bytes in signature %d", rlen);
	144	xfree(sigblob);
	145	return -1;
	146	}
	147	}
	148
	149	if (len != SIGBLOB_LEN) {
680cee3b	150	fatal("bad sigbloblen %u != SIGBLOB_LEN", len);
3c0ef626	151	}
	152
	153	/* parse signature */
e9a17296	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");
3c0ef626	160	BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
	161	BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
	162
12408a1b	163	/* clean up */
	164	memset(sigblob, 0, len);
	165	xfree(sigblob);
3c0ef626	166
3c0ef626	167	/* sha1 the data */
3c0ef626	168	EVP_DigestInit(&md, evp_md);
3c0ef626	169	EVP_DigestUpdate(&md, data, datalen);
e9a17296	170	EVP_DigestFinal(&md, digest, &dlen);
3c0ef626	171
3c0ef626	172	ret = DSA_do_verify(digest, dlen, sig, key->dsa);
e9a17296	173	memset(digest, 'd', sizeof(digest));
3c0ef626	174
3c0ef626	175	DSA_SIG_free(sig);
	176
	177	debug("ssh_dss_verify: signature %s",
	178	ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");
	179	return ret;
	180	}