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" 26 RCSID("$OpenBSD: ssh-rsa.c,v 1.8 2001/03/27 10:57:00 markus Exp $"); 27 28 #include <openssl/evp.h> 29 #include <openssl/err.h> 30 31 #include "xmalloc.h" 32 #include "log.h" 33 #include "buffer.h" 34 #include "bufaux.h" 35 #include "key.h" 36 #include "ssh-rsa.h" 37 #include "compat.h" 38 39 /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */ 40 int 41 ssh_rsa_sign( 42 Key *key, 43 u_char **sigp, int *lenp, 44 u_char *data, int datalen) 45 { 46 const EVP_MD *evp_md; 47 EVP_MD_CTX md; 48 u_char *digest, *sig, *ret; 49 u_int slen, dlen, len; 50 int ok, nid; 51 Buffer b; 52 53 if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) { 54 error("ssh_rsa_sign: no RSA key"); 55 return -1; 56 } 57 nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1; 58 if ((evp_md = EVP_get_digestbynid(nid)) == NULL) { 59 error("ssh_rsa_sign: EVP_get_digestbynid %d failed", nid); 60 return -1; 61 } 62 dlen = evp_md->md_size; 63 digest = xmalloc(dlen); 64 EVP_DigestInit(&md, evp_md); 65 EVP_DigestUpdate(&md, data, datalen); 66 EVP_DigestFinal(&md, digest, NULL); 67 68 slen = RSA_size(key->rsa); 69 sig = xmalloc(slen); 70 71 ok = RSA_sign(nid, digest, dlen, sig, &len, key->rsa); 72 memset(digest, 'd', dlen); 73 xfree(digest); 74 75 if (ok != 1) { 76 int ecode = ERR_get_error(); 77 error("ssh_rsa_sign: RSA_sign failed: %s", ERR_error_string(ecode, NULL)); 78 xfree(sig); 79 return -1; 80 } 81 if (len < slen) { 82 int diff = slen - len; 83 debug("slen %d > len %d", slen, len); 84 memmove(sig + diff, sig, len); 85 memset(sig, 0, diff); 86 } else if (len > slen) { 87 error("ssh_rsa_sign: slen %d slen2 %d", slen, len); 88 xfree(sig); 89 return -1; 90 } 91 /* encode signature */ 92 buffer_init(&b); 93 buffer_put_cstring(&b, "ssh-rsa"); 94 buffer_put_string(&b, sig, slen); 95 len = buffer_len(&b); 96 ret = xmalloc(len); 97 memcpy(ret, buffer_ptr(&b), len); 98 buffer_free(&b); 99 memset(sig, 's', slen); 100 xfree(sig); 101 102 if (lenp != NULL) 103 *lenp = len; 104 if (sigp != NULL) 105 *sigp = ret; 106 debug2("ssh_rsa_sign: done"); 107 return 0; 108 } 109 110 int 111 ssh_rsa_verify( 112 Key *key, 113 u_char *signature, int signaturelen, 114 u_char *data, int datalen) 115 { 116 Buffer b; 117 const EVP_MD *evp_md; 118 EVP_MD_CTX md; 119 char *ktype; 120 u_char *sigblob, *digest; 121 u_int len, dlen; 122 int rlen, ret, nid; 123 124 if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) { 125 error("ssh_rsa_verify: no RSA key"); 126 return -1; 127 } 128 if (BN_num_bits(key->rsa->n) < 768) { 129 error("ssh_rsa_verify: n too small: %d bits", 130 BN_num_bits(key->rsa->n)); 131 return -1; 132 } 133 buffer_init(&b); 134 buffer_append(&b, (char *) signature, signaturelen); 135 ktype = buffer_get_string(&b, NULL); 136 if (strcmp("ssh-rsa", ktype) != 0) { 137 error("ssh_rsa_verify: cannot handle type %s", ktype); 138 buffer_free(&b); 139 xfree(ktype); 140 return -1; 141 } 142 xfree(ktype); 143 sigblob = (u_char *)buffer_get_string(&b, &len); 144 rlen = buffer_len(&b); 145 buffer_free(&b); 146 if(rlen != 0) { 147 xfree(sigblob); 148 error("ssh_rsa_verify: remaining bytes in signature %d", rlen); 149 return -1; 150 } 151 nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1; 152 if ((evp_md = EVP_get_digestbynid(nid)) == NULL) { 153 xfree(sigblob); 154 error("ssh_rsa_verify: EVP_get_digestbynid %d failed", nid); 155 return -1; 156 } 157 dlen = evp_md->md_size; 158 digest = xmalloc(dlen); 159 EVP_DigestInit(&md, evp_md); 160 EVP_DigestUpdate(&md, data, datalen); 161 EVP_DigestFinal(&md, digest, NULL); 162 163 ret = RSA_verify(nid, digest, dlen, sigblob, len, key->rsa); 164 memset(digest, 'd', dlen); 165 xfree(digest); 166 memset(sigblob, 's', len); 167 xfree(sigblob); 168 if (ret == 0) { 169 int ecode = ERR_get_error(); 170 error("ssh_rsa_verify: RSA_verify failed: %s", ERR_error_string(ecode, NULL)); 171 } 172 debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : ""); 173 return ret; 174 } 175