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/*
* 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 1.18 2002/04/02 20:11:38 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, *ret;
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 %d > len %d", slen, len);
memmove(sig + diff, sig, len);
memset(sig, 0, diff);
} else if (len > slen) {
error("ssh_rsa_sign: slen %d slen2 %d", 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);
ret = xmalloc(len);
memcpy(ret, buffer_ptr(&b), len);
buffer_free(&b);
memset(sig, 's', slen);
xfree(sig);
if (lenp != NULL)
*lenp = len;
if (sigp != NULL)
*sigp = ret;
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;
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: n too small: %d bits",
BN_num_bits(key->rsa->n));
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;
}
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;
}
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