[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 1.2 2000/12/19 23:17:58 markus Exp $");

#include "ssh.h"
#include "xmalloc.h"
#include "buffer.h"
#include "bufaux.h"
#include "compat.h"

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

#include "key.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)
{
	u_char *digest;
	u_char *ret;
	DSA_SIG *sig;
	EVP_MD *evp_md = EVP_sha1();
	EVP_MD_CTX md;
	u_int rlen;
	u_int slen;
	u_int len;
	u_char sigblob[SIGBLOB_LEN];
	Buffer b;

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

	sig = DSA_do_sign(digest, evp_md->md_size, key->dsa);
	if (sig == NULL) {
		fatal("ssh_dss_sign: cannot sign");
	}

	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;
	}
	debug("sig size %d %d", rlen, slen);

	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) {
		debug("datafellows");
		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)
{
	Buffer b;
	u_char *digest;
	DSA_SIG *sig;
	EVP_MD *evp_md = EVP_sha1();
	EVP_MD_CTX md;
	u_char *sigblob;
	char *txt;
	u_int len, dlen;
	int rlen;
	int ret;

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

	if (!(datafellows & SSH_BUG_SIGBLOB) &&
	    signaturelen == SIGBLOB_LEN) {
		datafellows |= ~SSH_BUG_SIGBLOB;
		log("autodetect SSH_BUG_SIGBLOB");
	} else if ((datafellows & SSH_BUG_SIGBLOB) &&
	    signaturelen != SIGBLOB_LEN) {
		log("autoremove SSH_BUG_SIGBLOB");
		datafellows &= ~SSH_BUG_SIGBLOB;
	}

	debug("len %d datafellows %d", signaturelen, datafellows);

	/* fetch signature */
	if (datafellows & SSH_BUG_SIGBLOB) {
		sigblob = signature;
		len = signaturelen;
	} else {
		/* ietf-drafts */
		char *ktype;
		buffer_init(&b);
		buffer_append(&b, (char *) 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);
			return -1;
		}
		sigblob = (u_char *)buffer_get_string(&b, &len);
		rlen = buffer_len(&b);
		if(rlen != 0) {
			error("remaining bytes in signature %d", rlen);
			buffer_free(&b);
			return -1;
		}
		buffer_free(&b);
		xfree(ktype);
	}

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

	/* parse signature */
	sig = DSA_SIG_new();
	sig->r = BN_new();
	sig->s = BN_new();
	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);

	switch (ret) {
	case 1:
		txt = "correct";
		break;
	case 0:
		txt = "incorrect";
		break;
	case -1:
	default:
		txt = "error";
		break;
	}
	debug("ssh_dss_verify: signature %s", txt);
	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"
1e3b8b07	26	RCSID("$OpenBSD: ssh-dss.c,v 1.2 2000/12/19 23:17:58 markus Exp $");
4f8c6159	27
	28	#include "ssh.h"
	29	#include "xmalloc.h"
	30	#include "buffer.h"
	31	#include "bufaux.h"
	32	#include "compat.h"
	33
	34	#include <openssl/bn.h>
4f8c6159	35	#include <openssl/rsa.h>
	36	#include <openssl/dsa.h>
	37	#include <openssl/evp.h>
4f8c6159	38
4f8c6159	39	#include "key.h"
	40
	41	#define INTBLOB_LEN 20
	42	#define SIGBLOB_LEN (2*INTBLOB_LEN)
	43
4f8c6159	44	int
fa08c86b	45	ssh_dss_sign(
4f8c6159	46	Key *key,
1e3b8b07	47	u_char *sigp, int lenp,
1e3b8b07	48	u_char *data, int datalen)
4f8c6159	49	{
1e3b8b07	50	u_char *digest;
1e3b8b07	51	u_char *ret;
4f8c6159	52	DSA_SIG *sig;
	53	EVP_MD *evp_md = EVP_sha1();
	54	EVP_MD_CTX md;
1e3b8b07	55	u_int rlen;
	56	u_int slen;
	57	u_int len;
	58	u_char sigblob[SIGBLOB_LEN];
4f8c6159	59	Buffer b;
	60
	61	if (key == NULL \|\| key->type != KEY_DSA \|\| key->dsa == NULL) {
fa08c86b	62	error("ssh_dss_sign: no DSA key");
4f8c6159	63	return -1;
	64	}
	65	digest = xmalloc(evp_md->md_size);
	66	EVP_DigestInit(&md, evp_md);
a306f2dd	67	EVP_DigestUpdate(&md, data, datalen);
4f8c6159	68	EVP_DigestFinal(&md, digest, NULL);
	69
	70	sig = DSA_do_sign(digest, evp_md->md_size, key->dsa);
a306f2dd	71	if (sig == NULL) {
fa08c86b	72	fatal("ssh_dss_sign: cannot sign");
a306f2dd	73	}
4f8c6159	74
	75	rlen = BN_num_bytes(sig->r);
	76	slen = BN_num_bytes(sig->s);
	77	if (rlen > INTBLOB_LEN \|\| slen > INTBLOB_LEN) {
	78	error("bad sig size %d %d", rlen, slen);
	79	DSA_SIG_free(sig);
	80	return -1;
	81	}
	82	debug("sig size %d %d", rlen, slen);
	83
	84	memset(sigblob, 0, SIGBLOB_LEN);
	85	BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
	86	BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
	87	DSA_SIG_free(sig);
	88
d0c832f3	89	if (datafellows & SSH_BUG_SIGBLOB) {
4f8c6159	90	debug("datafellows");
	91	ret = xmalloc(SIGBLOB_LEN);
	92	memcpy(ret, sigblob, SIGBLOB_LEN);
	93	if (lenp != NULL)
	94	*lenp = SIGBLOB_LEN;
	95	if (sigp != NULL)
	96	*sigp = ret;
	97	} else {
	98	/* ietf-drafts */
	99	buffer_init(&b);
fa08c86b	100	buffer_put_cstring(&b, "ssh-dss");
4f8c6159	101	buffer_put_string(&b, sigblob, SIGBLOB_LEN);
	102	len = buffer_len(&b);
	103	ret = xmalloc(len);
	104	memcpy(ret, buffer_ptr(&b), len);
	105	buffer_free(&b);
	106	if (lenp != NULL)
	107	*lenp = len;
	108	if (sigp != NULL)
	109	*sigp = ret;
	110	}
	111	return 0;
	112	}
	113	int
fa08c86b	114	ssh_dss_verify(
4f8c6159	115	Key *key,
1e3b8b07	116	u_char *signature, int signaturelen,
1e3b8b07	117	u_char *data, int datalen)
4f8c6159	118	{
4f8c6159	119	Buffer b;
1e3b8b07	120	u_char *digest;
4f8c6159	121	DSA_SIG *sig;
	122	EVP_MD *evp_md = EVP_sha1();
	123	EVP_MD_CTX md;
1e3b8b07	124	u_char *sigblob;
4f8c6159	125	char *txt;
1e3b8b07	126	u_int len, dlen;
4f8c6159	127	int rlen;
	128	int ret;
	129
	130	if (key == NULL \|\| key->type != KEY_DSA \|\| key->dsa == NULL) {
fa08c86b	131	error("ssh_dss_verify: no DSA key");
4f8c6159	132	return -1;
	133	}
	134
d0c832f3	135	if (!(datafellows & SSH_BUG_SIGBLOB) &&
	136	signaturelen == SIGBLOB_LEN) {
	137	datafellows \|= ~SSH_BUG_SIGBLOB;
	138	log("autodetect SSH_BUG_SIGBLOB");
	139	} else if ((datafellows & SSH_BUG_SIGBLOB) &&
	140	signaturelen != SIGBLOB_LEN) {
	141	log("autoremove SSH_BUG_SIGBLOB");
	142	datafellows &= ~SSH_BUG_SIGBLOB;
4f8c6159	143	}
	144
	145	debug("len %d datafellows %d", signaturelen, datafellows);
	146
	147	/* fetch signature */
d0c832f3	148	if (datafellows & SSH_BUG_SIGBLOB) {
4f8c6159	149	sigblob = signature;
	150	len = signaturelen;
	151	} else {
	152	/* ietf-drafts */
74fc9186	153	char *ktype;
4f8c6159	154	buffer_init(&b);
	155	buffer_append(&b, (char *) signature, signaturelen);
	156	ktype = buffer_get_string(&b, NULL);
fa08c86b	157	if (strcmp("ssh-dss", ktype) != 0) {
fa08c86b	158	error("ssh_dss_verify: cannot handle type %s", ktype);
74fc9186	159	buffer_free(&b);
	160	return -1;
	161	}
1e3b8b07	162	sigblob = (u_char *)buffer_get_string(&b, &len);
4f8c6159	163	rlen = buffer_len(&b);
74fc9186	164	if(rlen != 0) {
4f8c6159	165	error("remaining bytes in signature %d", rlen);
74fc9186	166	buffer_free(&b);
	167	return -1;
	168	}
4f8c6159	169	buffer_free(&b);
74fc9186	170	xfree(ktype);
4f8c6159	171	}
	172
	173	if (len != SIGBLOB_LEN) {
	174	fatal("bad sigbloblen %d != SIGBLOB_LEN", len);
	175	}
	176
	177	/* parse signature */
	178	sig = DSA_SIG_new();
	179	sig->r = BN_new();
	180	sig->s = BN_new();
	181	BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
	182	BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
d0c832f3	183
d0c832f3	184	if (!(datafellows & SSH_BUG_SIGBLOB)) {
4f8c6159	185	memset(sigblob, 0, len);
	186	xfree(sigblob);
	187	}
	188
a306f2dd	189	/* sha1 the data */
fa08c86b	190	dlen = evp_md->md_size;
fa08c86b	191	digest = xmalloc(dlen);
4f8c6159	192	EVP_DigestInit(&md, evp_md);
a306f2dd	193	EVP_DigestUpdate(&md, data, datalen);
4f8c6159	194	EVP_DigestFinal(&md, digest, NULL);
4f8c6159	195
fa08c86b	196	ret = DSA_do_verify(digest, dlen, sig, key->dsa);
4f8c6159	197
fa08c86b	198	memset(digest, 0, dlen);
4f8c6159	199	xfree(digest);
	200	DSA_SIG_free(sig);
	201
	202	switch (ret) {
	203	case 1:
	204	txt = "correct";
	205	break;
	206	case 0:
	207	txt = "incorrect";
	208	break;
	209	case -1:
	210	default:
	211	txt = "error";
	212	break;
	213	}
fa08c86b	214	debug("ssh_dss_verify: signature %s", txt);
4f8c6159	215	return ret;
4f8c6159	216	}