| /* |
| * 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 1.24 2002/08/02 21:23:41 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) { |
| u_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) { |
| u_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; |
| } |