[openssh.git] / ssh-rsa.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-rsa.c,v 1.23 2002/07/04 10:41:47 markus Exp $");

#include <openssl/evp.h>
#include <openssl/err.h>

#include "xmalloc.h"
#include "log.h"
#include "buffer.h"
#include "bufaux.h"
#include "key.h"
#include "ssh-rsa.h"
#include "compat.h"
#include "ssh.h"

/* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
int
ssh_rsa_sign(Key *key, u_char **sigp, u_int *lenp,
    u_char *data, u_int datalen)
{
	const EVP_MD *evp_md;
	EVP_MD_CTX md;
	u_char digest[EVP_MAX_MD_SIZE], *sig;
	u_int slen, dlen, len;
	int ok, nid;
	Buffer b;

	if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) {
		error("ssh_rsa_sign: no RSA key");
		return -1;
	}
	nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
	if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
		error("ssh_rsa_sign: EVP_get_digestbynid %d failed", nid);
		return -1;
	}
	EVP_DigestInit(&md, evp_md);
	EVP_DigestUpdate(&md, data, datalen);
	EVP_DigestFinal(&md, digest, &dlen);

	slen = RSA_size(key->rsa);
	sig = xmalloc(slen);

	ok = RSA_sign(nid, digest, dlen, sig, &len, key->rsa);
	memset(digest, 'd', sizeof(digest));

	if (ok != 1) {
		int ecode = ERR_get_error();
		error("ssh_rsa_sign: RSA_sign failed: %s",
		    ERR_error_string(ecode, NULL));
		xfree(sig);
		return -1;
	}
	if (len < slen) {
		int diff = slen - len;
		debug("slen %u > len %u", slen, len);
		memmove(sig + diff, sig, len);
		memset(sig, 0, diff);
	} else if (len > slen) {
		error("ssh_rsa_sign: slen %u slen2 %u", slen, len);
		xfree(sig);
		return -1;
	}
	/* encode signature */
	buffer_init(&b);
	buffer_put_cstring(&b, "ssh-rsa");
	buffer_put_string(&b, sig, slen);
	len = buffer_len(&b);
	if (lenp != NULL)
		*lenp = len;
	if (sigp != NULL) {
		*sigp = xmalloc(len);
		memcpy(*sigp, buffer_ptr(&b), len);
	}
	buffer_free(&b);
	memset(sig, 's', slen);
	xfree(sig);

	return 0;
}

int
ssh_rsa_verify(Key *key, u_char *signature, u_int signaturelen,
    u_char *data, u_int datalen)
{
	Buffer b;
	const EVP_MD *evp_md;
	EVP_MD_CTX md;
	char *ktype;
	u_char digest[EVP_MAX_MD_SIZE], *sigblob;
	u_int len, dlen, modlen;
	int rlen, ret, nid;

	if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) {
		error("ssh_rsa_verify: no RSA key");
		return -1;
	}
	if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) {
		error("ssh_rsa_verify: RSA modulus too small: %d < minimum %d bits",
		    BN_num_bits(key->rsa->n), SSH_RSA_MINIMUM_MODULUS_SIZE);
		return -1;
	}
	buffer_init(&b);
	buffer_append(&b, signature, signaturelen);
	ktype = buffer_get_string(&b, NULL);
	if (strcmp("ssh-rsa", ktype) != 0) {
		error("ssh_rsa_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_rsa_verify: remaining bytes in signature %d", rlen);
		xfree(sigblob);
		return -1;
	}
	/* RSA_verify expects a signature of RSA_size */
	modlen = RSA_size(key->rsa);
	if (len > modlen) {
		error("ssh_rsa_verify: len %u > modlen %u", len, modlen);
		xfree(sigblob);
		return -1;
	} else if (len < modlen) {
		int diff = modlen - len;
		debug("ssh_rsa_verify: add padding: modlen %u > len %u",
		    modlen, len);
		sigblob = xrealloc(sigblob, modlen);
		memmove(sigblob + diff, sigblob, len);
		memset(sigblob, 0, diff);
		len = modlen;
	}
	nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
	if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
		error("ssh_rsa_verify: EVP_get_digestbynid %d failed", nid);
		xfree(sigblob);
		return -1;
	}
	EVP_DigestInit(&md, evp_md);
	EVP_DigestUpdate(&md, data, datalen);
	EVP_DigestFinal(&md, digest, &dlen);

	ret = RSA_verify(nid, digest, dlen, sigblob, len, key->rsa);
	memset(digest, 'd', sizeof(digest));
	memset(sigblob, 's', len);
	xfree(sigblob);
	if (ret == 0) {
		int ecode = ERR_get_error();
		error("ssh_rsa_verify: RSA_verify failed: %s",
		    ERR_error_string(ecode, NULL));
	}
	debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : "");
	return ret;
}
Commit	Line	Data
fa08c86b	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"
eb9f2fab	26	RCSID("$OpenBSD: ssh-rsa.c,v 1.23 2002/07/04 10:41:47 markus Exp $");
fa08c86b	27
fa08c86b	28	#include <openssl/evp.h>
fa08c86b	29	#include <openssl/err.h>
fa08c86b	30
42f11eb2	31	#include "xmalloc.h"
	32	#include "log.h"
	33	#include "buffer.h"
	34	#include "bufaux.h"
fa08c86b	35	#include "key.h"
5ca51e19	36	#include "ssh-rsa.h"
a4da628b	37	#include "compat.h"
82b00264	38	#include "ssh.h"
fa08c86b	39
fa08c86b	40	/* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
fa08c86b	41	int
d6133f43	42	ssh_rsa_sign(Key key, u_char sigp, u_int lenp,
c66f9d0e	43	u_char *data, u_int datalen)
fa08c86b	44	{
1a92bd7e	45	const EVP_MD *evp_md;
fa08c86b	46	EVP_MD_CTX md;
eb9f2fab	47	u_char digest[EVP_MAX_MD_SIZE], *sig;
1e3b8b07	48	u_int slen, dlen, len;
1a92bd7e	49	int ok, nid;
fa08c86b	50	Buffer b;
	51
	52	if (key == NULL \|\| key->type != KEY_RSA \|\| key->rsa == NULL) {
	53	error("ssh_rsa_sign: no RSA key");
	54	return -1;
	55	}
a4da628b	56	nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
1a92bd7e	57	if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
	58	error("ssh_rsa_sign: EVP_get_digestbynid %d failed", nid);
	59	return -1;
	60	}
fa08c86b	61	EVP_DigestInit(&md, evp_md);
fa08c86b	62	EVP_DigestUpdate(&md, data, datalen);
087dea86	63	EVP_DigestFinal(&md, digest, &dlen);
fa08c86b	64
1a92bd7e	65	slen = RSA_size(key->rsa);
	66	sig = xmalloc(slen);
	67
	68	ok = RSA_sign(nid, digest, dlen, sig, &len, key->rsa);
087dea86	69	memset(digest, 'd', sizeof(digest));
fa08c86b	70
	71	if (ok != 1) {
	72	int ecode = ERR_get_error();
d6133f43	73	error("ssh_rsa_sign: RSA_sign failed: %s",
d6133f43	74	ERR_error_string(ecode, NULL));
fa08c86b	75	xfree(sig);
	76	return -1;
	77	}
	78	if (len < slen) {
	79	int diff = slen - len;
d6133f43	80	debug("slen %u > len %u", slen, len);
fa08c86b	81	memmove(sig + diff, sig, len);
	82	memset(sig, 0, diff);
	83	} else if (len > slen) {
d6133f43	84	error("ssh_rsa_sign: slen %u slen2 %u", slen, len);
fa08c86b	85	xfree(sig);
	86	return -1;
	87	}
	88	/* encode signature */
	89	buffer_init(&b);
	90	buffer_put_cstring(&b, "ssh-rsa");
	91	buffer_put_string(&b, sig, slen);
	92	len = buffer_len(&b);
eb9f2fab	93	if (lenp != NULL)
	94	*lenp = len;
	95	if (sigp != NULL) {
	96	*sigp = xmalloc(len);
	97	memcpy(*sigp, buffer_ptr(&b), len);
	98	}
fa08c86b	99	buffer_free(&b);
	100	memset(sig, 's', slen);
	101	xfree(sig);
	102
fa08c86b	103	return 0;
	104	}
	105
	106	int
d6133f43	107	ssh_rsa_verify(Key key, u_char signature, u_int signaturelen,
c66f9d0e	108	u_char *data, u_int datalen)
fa08c86b	109	{
fa08c86b	110	Buffer b;
1a92bd7e	111	const EVP_MD *evp_md;
fa08c86b	112	EVP_MD_CTX md;
fa08c86b	113	char *ktype;
087dea86	114	u_char digest[EVP_MAX_MD_SIZE], *sigblob;
88f24e9d	115	u_int len, dlen, modlen;
1a92bd7e	116	int rlen, ret, nid;
fa08c86b	117
	118	if (key == NULL \|\| key->type != KEY_RSA \|\| key->rsa == NULL) {
	119	error("ssh_rsa_verify: no RSA key");
	120	return -1;
	121	}
82b00264	122	if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) {
b7ced7d1	123	error("ssh_rsa_verify: RSA modulus too small: %d < minimum %d bits",
b7ced7d1	124	BN_num_bits(key->rsa->n), SSH_RSA_MINIMUM_MODULUS_SIZE);
b5c334cc	125	return -1;
b5c334cc	126	}
fa08c86b	127	buffer_init(&b);
cf54363d	128	buffer_append(&b, signature, signaturelen);
fa08c86b	129	ktype = buffer_get_string(&b, NULL);
	130	if (strcmp("ssh-rsa", ktype) != 0) {
	131	error("ssh_rsa_verify: cannot handle type %s", ktype);
	132	buffer_free(&b);
	133	xfree(ktype);
	134	return -1;
	135	}
	136	xfree(ktype);
cf54363d	137	sigblob = buffer_get_string(&b, &len);
fa08c86b	138	rlen = buffer_len(&b);
fa08c86b	139	buffer_free(&b);
6aacefa7	140	if (rlen != 0) {
fa08c86b	141	error("ssh_rsa_verify: remaining bytes in signature %d", rlen);
abc4e9a7	142	xfree(sigblob);
fa08c86b	143	return -1;
fa08c86b	144	}
88f24e9d	145	/* RSA_verify expects a signature of RSA_size */
	146	modlen = RSA_size(key->rsa);
	147	if (len > modlen) {
d6133f43	148	error("ssh_rsa_verify: len %u > modlen %u", len, modlen);
88f24e9d	149	xfree(sigblob);
	150	return -1;
	151	} else if (len < modlen) {
	152	int diff = modlen - len;
d6133f43	153	debug("ssh_rsa_verify: add padding: modlen %u > len %u",
88f24e9d	154	modlen, len);
	155	sigblob = xrealloc(sigblob, modlen);
	156	memmove(sigblob + diff, sigblob, len);
	157	memset(sigblob, 0, diff);
	158	len = modlen;
	159	}
a4da628b	160	nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
1a92bd7e	161	if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
1a92bd7e	162	error("ssh_rsa_verify: EVP_get_digestbynid %d failed", nid);
abc4e9a7	163	xfree(sigblob);
1a92bd7e	164	return -1;
1a92bd7e	165	}
fa08c86b	166	EVP_DigestInit(&md, evp_md);
fa08c86b	167	EVP_DigestUpdate(&md, data, datalen);
087dea86	168	EVP_DigestFinal(&md, digest, &dlen);
fa08c86b	169
1a92bd7e	170	ret = RSA_verify(nid, digest, dlen, sigblob, len, key->rsa);
087dea86	171	memset(digest, 'd', sizeof(digest));
fa08c86b	172	memset(sigblob, 's', len);
	173	xfree(sigblob);
	174	if (ret == 0) {
	175	int ecode = ERR_get_error();
d6133f43	176	error("ssh_rsa_verify: RSA_verify failed: %s",
d6133f43	177	ERR_error_string(ecode, NULL));
fa08c86b	178	}
	179	debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : "");
	180	return ret;
	181	}