[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 1.14 2002/02/28 15:46:33 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;
	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 %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;
	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 %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
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"
e9a17296	26	RCSID("$OpenBSD: ssh-dss.c,v 1.14 2002/02/28 15:46:33 markus 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"
	37	#include "ssh-dss.h"
	38
	39	#define INTBLOB_LEN 20
	40	#define SIGBLOB_LEN (2*INTBLOB_LEN)
	41
	42	int
	43	ssh_dss_sign(
	44	Key *key,
e9a17296	45	u_char *sigp, u_int lenp,
e9a17296	46	u_char *data, u_int datalen)
3c0ef626	47	{
3c0ef626	48	DSA_SIG *sig;
e9a17296	49	const EVP_MD *evp_md = EVP_sha1();
3c0ef626	50	EVP_MD_CTX md;
e9a17296	51	u_char *ret, digest[EVP_MAX_MD_SIZE], sigblob[SIGBLOB_LEN];
3c0ef626	52	u_int rlen, slen, len, dlen;
	53	Buffer b;
	54
	55	if (key == NULL \|\| key->type != KEY_DSA \|\| key->dsa == NULL) {
	56	error("ssh_dss_sign: no DSA key");
	57	return -1;
	58	}
3c0ef626	59	EVP_DigestInit(&md, evp_md);
3c0ef626	60	EVP_DigestUpdate(&md, data, datalen);
e9a17296	61	EVP_DigestFinal(&md, digest, &dlen);
3c0ef626	62
3c0ef626	63	sig = DSA_do_sign(digest, dlen, key->dsa);
e9a17296	64	memset(digest, 'd', sizeof(digest));
3c0ef626	65
3c0ef626	66	if (sig == NULL) {
	67	error("ssh_dss_sign: sign failed");
	68	return -1;
	69	}
	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	}
	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
	83	if (datafellows & SSH_BUG_SIGBLOB) {
	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);
	93	buffer_put_cstring(&b, "ssh-dss");
	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
	107	ssh_dss_verify(
	108	Key *key,
e9a17296	109	u_char *signature, u_int signaturelen,
e9a17296	110	u_char *data, u_int datalen)
3c0ef626	111	{
3c0ef626	112	DSA_SIG *sig;
e9a17296	113	const EVP_MD *evp_md = EVP_sha1();
3c0ef626	114	EVP_MD_CTX md;
e9a17296	115	u_char digest[EVP_MAX_MD_SIZE], *sigblob;
3c0ef626	116	u_int len, dlen;
	117	int rlen, ret;
	118	Buffer b;
	119
	120	if (key == NULL \|\| key->type != KEY_DSA \|\| key->dsa == NULL) {
	121	error("ssh_dss_verify: no DSA key");
	122	return -1;
	123	}
	124
	125	/* fetch signature */
	126	if (datafellows & SSH_BUG_SIGBLOB) {
	127	sigblob = signature;
	128	len = signaturelen;
	129	} else {
	130	/* ietf-drafts */
	131	char *ktype;
	132	buffer_init(&b);
	133	buffer_append(&b, signature, signaturelen);
	134	ktype = buffer_get_string(&b, NULL);
	135	if (strcmp("ssh-dss", ktype) != 0) {
	136	error("ssh_dss_verify: cannot handle type %s", ktype);
	137	buffer_free(&b);
	138	xfree(ktype);
	139	return -1;
	140	}
	141	xfree(ktype);
	142	sigblob = buffer_get_string(&b, &len);
	143	rlen = buffer_len(&b);
	144	buffer_free(&b);
e9a17296	145	if (rlen != 0) {
3c0ef626	146	error("ssh_dss_verify: "
	147	"remaining bytes in signature %d", rlen);
	148	xfree(sigblob);
	149	return -1;
	150	}
	151	}
	152
	153	if (len != SIGBLOB_LEN) {
	154	fatal("bad sigbloblen %d != SIGBLOB_LEN", len);
	155	}
	156
	157	/* parse signature */
e9a17296	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");
3c0ef626	164	BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
	165	BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
	166
	167	if (!(datafellows & SSH_BUG_SIGBLOB)) {
	168	memset(sigblob, 0, len);
	169	xfree(sigblob);
	170	}
	171
	172	/* sha1 the data */
3c0ef626	173	EVP_DigestInit(&md, evp_md);
3c0ef626	174	EVP_DigestUpdate(&md, data, datalen);
e9a17296	175	EVP_DigestFinal(&md, digest, &dlen);
3c0ef626	176
3c0ef626	177	ret = DSA_do_verify(digest, dlen, sig, key->dsa);
e9a17296	178	memset(digest, 'd', sizeof(digest));
3c0ef626	179
3c0ef626	180	DSA_SIG_free(sig);
	181
	182	debug("ssh_dss_verify: signature %s",
	183	ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");
	184	return ret;
	185	}