[openssh.git] / dsa.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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Markus Friedl.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * 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: dsa.c,v 1.9 2000/06/20 01:39:41 markus Exp $");

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

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

#include <openssl/hmac.h>
#include "kex.h"
#include "key.h"
#include "uuencode.h"

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

Key *
dsa_key_from_blob(
    char *blob, int blen)
{
	Buffer b;
	char *ktype;
	int rlen;
	DSA *dsa;
	Key *key;

#ifdef DEBUG_DSS
	dump_base64(stderr, blob, blen);
#endif
	/* fetch & parse DSA/DSS pubkey */
	key = key_new(KEY_DSA);
	dsa = key->dsa;
	buffer_init(&b);
	buffer_append(&b, blob, blen);
	ktype = buffer_get_string(&b, NULL);
	if (strcmp(KEX_DSS, ktype) != 0) {
		error("dsa_key_from_blob: cannot handle type %s", ktype);
		key_free(key);
		return NULL;
	}
	buffer_get_bignum2(&b, dsa->p);
	buffer_get_bignum2(&b, dsa->q);
	buffer_get_bignum2(&b, dsa->g);
	buffer_get_bignum2(&b, dsa->pub_key);
	rlen = buffer_len(&b);
	if(rlen != 0)
		error("dsa_key_from_blob: remaining bytes in key blob %d", rlen);
	buffer_free(&b);

	debug("keytype %s", ktype);
#ifdef DEBUG_DSS
	DSA_print_fp(stderr, dsa, 8);
#endif
	return key;
}
int
dsa_make_key_blob(Key *key, unsigned char **blobp, unsigned int *lenp)
{
	Buffer b;
	int len;
	unsigned char *buf;

	if (key == NULL || key->type != KEY_DSA)
		return 0;
	buffer_init(&b);
	buffer_put_cstring(&b, KEX_DSS);
	buffer_put_bignum2(&b, key->dsa->p);
	buffer_put_bignum2(&b, key->dsa->q);
	buffer_put_bignum2(&b, key->dsa->g);
	buffer_put_bignum2(&b, key->dsa->pub_key);
	len = buffer_len(&b);
	buf = xmalloc(len);
	memcpy(buf, buffer_ptr(&b), len);
	memset(buffer_ptr(&b), 0, len);
	buffer_free(&b);
	if (lenp != NULL)
		*lenp = len;
	if (blobp != NULL)
		*blobp = buf;
	return len;
}
int
dsa_sign(
    Key *key,
    unsigned char **sigp, int *lenp,
    unsigned char *data, int datalen)
{
	unsigned char *digest;
	unsigned char *ret;
	DSA_SIG *sig;
	EVP_MD *evp_md = EVP_sha1();
	EVP_MD_CTX md;
	unsigned int rlen;
	unsigned int slen;
	unsigned int len;
	unsigned char sigblob[SIGBLOB_LEN];
	Buffer b;

	if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
		error("dsa_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("dsa_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, KEX_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
dsa_verify(
    Key *key,
    unsigned char *signature, int signaturelen,
    unsigned char *data, int datalen)
{
	Buffer b;
	unsigned char *digest;
	DSA_SIG *sig;
	EVP_MD *evp_md = EVP_sha1();
	EVP_MD_CTX md;
	unsigned char *sigblob;
	char *txt;
	unsigned int len;
	int rlen;
	int ret;

	if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
		error("dsa_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(KEX_DSS, ktype) != 0) {
			error("dsa_verify: cannot handle type %s", ktype);
			buffer_free(&b);
			return -1;
		}
		sigblob = (unsigned 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 */
	digest = xmalloc(evp_md->md_size);
	EVP_DigestInit(&md, evp_md);
	EVP_DigestUpdate(&md, data, datalen);
	EVP_DigestFinal(&md, digest, NULL);

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

	memset(digest, 0, evp_md->md_size);
	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("dsa_verify: signature %s", txt);
	return ret;
}

Key *
dsa_generate_key(unsigned int bits)
{
	DSA *dsa = DSA_generate_parameters(bits, NULL, 0, NULL, NULL, NULL, NULL);
	Key *k;
	if (dsa == NULL) {
		fatal("DSA_generate_parameters failed");
	}
	if (!DSA_generate_key(dsa)) {
		fatal("DSA_generate_keys failed");
	}

	k = key_new(KEY_EMPTY);
	k->type = KEY_DSA;
	k->dsa = dsa;
	return k;
}
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.
	12	* 3. All advertising materials mentioning features or use of this software
	13	* must display the following acknowledgement:
	14	* This product includes software developed by Markus Friedl.
	15	* 4. The name of the author may not be used to endorse or promote products
	16	* derived from this software without specific prior written permission.
	17	*
	18	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	19	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	20	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	21	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	22	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	23	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	24	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	25	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	26	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	27	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	28	*/
	29
	30	#include "includes.h"
74fc9186	31	RCSID("$OpenBSD: dsa.c,v 1.9 2000/06/20 01:39:41 markus Exp $");
4f8c6159	32
	33	#include "ssh.h"
	34	#include "xmalloc.h"
	35	#include "buffer.h"
	36	#include "bufaux.h"
	37	#include "compat.h"
	38
	39	#include <openssl/bn.h>
	40	#include <openssl/dh.h>
	41	#include <openssl/rsa.h>
	42	#include <openssl/dsa.h>
	43	#include <openssl/evp.h>
	44	#include <openssl/bio.h>
	45	#include <openssl/pem.h>
	46
	47	#include <openssl/hmac.h>
	48	#include "kex.h"
	49	#include "key.h"
a306f2dd	50	#include "uuencode.h"
4f8c6159	51
	52	#define INTBLOB_LEN 20
	53	#define SIGBLOB_LEN (2*INTBLOB_LEN)
	54
	55	Key *
a306f2dd	56	dsa_key_from_blob(
a306f2dd	57	char *blob, int blen)
4f8c6159	58	{
	59	Buffer b;
	60	char *ktype;
	61	int rlen;
	62	DSA *dsa;
	63	Key *key;
	64
a306f2dd	65	#ifdef DEBUG_DSS
1d1ffb87	66	dump_base64(stderr, blob, blen);
a306f2dd	67	#endif
4f8c6159	68	/* fetch & parse DSA/DSS pubkey */
	69	key = key_new(KEY_DSA);
	70	dsa = key->dsa;
	71	buffer_init(&b);
a306f2dd	72	buffer_append(&b, blob, blen);
4f8c6159	73	ktype = buffer_get_string(&b, NULL);
4f8c6159	74	if (strcmp(KEX_DSS, ktype) != 0) {
74fc9186	75	error("dsa_key_from_blob: cannot handle type %s", ktype);
4f8c6159	76	key_free(key);
	77	return NULL;
	78	}
	79	buffer_get_bignum2(&b, dsa->p);
	80	buffer_get_bignum2(&b, dsa->q);
	81	buffer_get_bignum2(&b, dsa->g);
	82	buffer_get_bignum2(&b, dsa->pub_key);
	83	rlen = buffer_len(&b);
	84	if(rlen != 0)
a306f2dd	85	error("dsa_key_from_blob: remaining bytes in key blob %d", rlen);
4f8c6159	86	buffer_free(&b);
	87
	88	debug("keytype %s", ktype);
	89	#ifdef DEBUG_DSS
	90	DSA_print_fp(stderr, dsa, 8);
	91	#endif
	92	return key;
	93	}
4f8c6159	94	int
a306f2dd	95	dsa_make_key_blob(Key key, unsigned char blobp, unsigned int lenp)
4f8c6159	96	{
	97	Buffer b;
	98	int len;
	99	unsigned char *buf;
	100
	101	if (key == NULL \|\| key->type != KEY_DSA)
	102	return 0;
	103	buffer_init(&b);
	104	buffer_put_cstring(&b, KEX_DSS);
	105	buffer_put_bignum2(&b, key->dsa->p);
	106	buffer_put_bignum2(&b, key->dsa->q);
	107	buffer_put_bignum2(&b, key->dsa->g);
	108	buffer_put_bignum2(&b, key->dsa->pub_key);
	109	len = buffer_len(&b);
	110	buf = xmalloc(len);
	111	memcpy(buf, buffer_ptr(&b), len);
	112	memset(buffer_ptr(&b), 0, len);
	113	buffer_free(&b);
	114	if (lenp != NULL)
	115	*lenp = len;
	116	if (blobp != NULL)
	117	*blobp = buf;
	118	return len;
	119	}
	120	int
	121	dsa_sign(
	122	Key *key,
	123	unsigned char *sigp, int lenp,
a306f2dd	124	unsigned char *data, int datalen)
4f8c6159	125	{
	126	unsigned char *digest;
	127	unsigned char *ret;
	128	DSA_SIG *sig;
	129	EVP_MD *evp_md = EVP_sha1();
	130	EVP_MD_CTX md;
	131	unsigned int rlen;
	132	unsigned int slen;
	133	unsigned int len;
	134	unsigned char sigblob[SIGBLOB_LEN];
	135	Buffer b;
	136
	137	if (key == NULL \|\| key->type != KEY_DSA \|\| key->dsa == NULL) {
	138	error("dsa_sign: no DSA key");
	139	return -1;
	140	}
	141	digest = xmalloc(evp_md->md_size);
	142	EVP_DigestInit(&md, evp_md);
a306f2dd	143	EVP_DigestUpdate(&md, data, datalen);
4f8c6159	144	EVP_DigestFinal(&md, digest, NULL);
	145
	146	sig = DSA_do_sign(digest, evp_md->md_size, key->dsa);
a306f2dd	147	if (sig == NULL) {
	148	fatal("dsa_sign: cannot sign");
	149	}
4f8c6159	150
	151	rlen = BN_num_bytes(sig->r);
	152	slen = BN_num_bytes(sig->s);
	153	if (rlen > INTBLOB_LEN \|\| slen > INTBLOB_LEN) {
	154	error("bad sig size %d %d", rlen, slen);
	155	DSA_SIG_free(sig);
	156	return -1;
	157	}
	158	debug("sig size %d %d", rlen, slen);
	159
	160	memset(sigblob, 0, SIGBLOB_LEN);
	161	BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
	162	BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
	163	DSA_SIG_free(sig);
	164
d0c832f3	165	if (datafellows & SSH_BUG_SIGBLOB) {
4f8c6159	166	debug("datafellows");
	167	ret = xmalloc(SIGBLOB_LEN);
	168	memcpy(ret, sigblob, SIGBLOB_LEN);
	169	if (lenp != NULL)
	170	*lenp = SIGBLOB_LEN;
	171	if (sigp != NULL)
	172	*sigp = ret;
	173	} else {
	174	/* ietf-drafts */
	175	buffer_init(&b);
	176	buffer_put_cstring(&b, KEX_DSS);
	177	buffer_put_string(&b, sigblob, SIGBLOB_LEN);
	178	len = buffer_len(&b);
	179	ret = xmalloc(len);
	180	memcpy(ret, buffer_ptr(&b), len);
	181	buffer_free(&b);
	182	if (lenp != NULL)
	183	*lenp = len;
	184	if (sigp != NULL)
	185	*sigp = ret;
	186	}
	187	return 0;
	188	}
	189	int
	190	dsa_verify(
	191	Key *key,
	192	unsigned char *signature, int signaturelen,
a306f2dd	193	unsigned char *data, int datalen)
4f8c6159	194	{
	195	Buffer b;
	196	unsigned char *digest;
	197	DSA_SIG *sig;
	198	EVP_MD *evp_md = EVP_sha1();
	199	EVP_MD_CTX md;
4f8c6159	200	unsigned char *sigblob;
	201	char *txt;
	202	unsigned int len;
	203	int rlen;
	204	int ret;
	205
	206	if (key == NULL \|\| key->type != KEY_DSA \|\| key->dsa == NULL) {
	207	error("dsa_verify: no DSA key");
	208	return -1;
	209	}
	210
d0c832f3	211	if (!(datafellows & SSH_BUG_SIGBLOB) &&
	212	signaturelen == SIGBLOB_LEN) {
	213	datafellows \|= ~SSH_BUG_SIGBLOB;
	214	log("autodetect SSH_BUG_SIGBLOB");
	215	} else if ((datafellows & SSH_BUG_SIGBLOB) &&
	216	signaturelen != SIGBLOB_LEN) {
	217	log("autoremove SSH_BUG_SIGBLOB");
	218	datafellows &= ~SSH_BUG_SIGBLOB;
4f8c6159	219	}
	220
	221	debug("len %d datafellows %d", signaturelen, datafellows);
	222
	223	/* fetch signature */
d0c832f3	224	if (datafellows & SSH_BUG_SIGBLOB) {
4f8c6159	225	sigblob = signature;
	226	len = signaturelen;
	227	} else {
	228	/* ietf-drafts */
74fc9186	229	char *ktype;
4f8c6159	230	buffer_init(&b);
	231	buffer_append(&b, (char *) signature, signaturelen);
	232	ktype = buffer_get_string(&b, NULL);
74fc9186	233	if (strcmp(KEX_DSS, ktype) != 0) {
	234	error("dsa_verify: cannot handle type %s", ktype);
	235	buffer_free(&b);
	236	return -1;
	237	}
4f8c6159	238	sigblob = (unsigned char *)buffer_get_string(&b, &len);
4f8c6159	239	rlen = buffer_len(&b);
74fc9186	240	if(rlen != 0) {
4f8c6159	241	error("remaining bytes in signature %d", rlen);
74fc9186	242	buffer_free(&b);
	243	return -1;
	244	}
4f8c6159	245	buffer_free(&b);
74fc9186	246	xfree(ktype);
4f8c6159	247	}
	248
	249	if (len != SIGBLOB_LEN) {
	250	fatal("bad sigbloblen %d != SIGBLOB_LEN", len);
	251	}
	252
	253	/* parse signature */
	254	sig = DSA_SIG_new();
	255	sig->r = BN_new();
	256	sig->s = BN_new();
	257	BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
	258	BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
d0c832f3	259
d0c832f3	260	if (!(datafellows & SSH_BUG_SIGBLOB)) {
4f8c6159	261	memset(sigblob, 0, len);
	262	xfree(sigblob);
	263	}
	264
a306f2dd	265	/* sha1 the data */
4f8c6159	266	digest = xmalloc(evp_md->md_size);
4f8c6159	267	EVP_DigestInit(&md, evp_md);
a306f2dd	268	EVP_DigestUpdate(&md, data, datalen);
4f8c6159	269	EVP_DigestFinal(&md, digest, NULL);
	270
	271	ret = DSA_do_verify(digest, evp_md->md_size, sig, key->dsa);
	272
	273	memset(digest, 0, evp_md->md_size);
	274	xfree(digest);
	275	DSA_SIG_free(sig);
	276
	277	switch (ret) {
	278	case 1:
	279	txt = "correct";
	280	break;
	281	case 0:
	282	txt = "incorrect";
	283	break;
	284	case -1:
	285	default:
	286	txt = "error";
	287	break;
	288	}
	289	debug("dsa_verify: signature %s", txt);
	290	return ret;
	291	}
a306f2dd	292
	293	Key *
	294	dsa_generate_key(unsigned int bits)
	295	{
	296	DSA *dsa = DSA_generate_parameters(bits, NULL, 0, NULL, NULL, NULL, NULL);
	297	Key *k;
	298	if (dsa == NULL) {
	299	fatal("DSA_generate_parameters failed");
	300	}
	301	if (!DSA_generate_key(dsa)) {
	302	fatal("DSA_generate_keys failed");
	303	}
	304
	305	k = key_new(KEY_EMPTY);
	306	k->type = KEY_DSA;
	307	k->dsa = dsa;
	308	return k;
	309	}