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 1.14 2001/12/05 10:06:12 deraadt 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 if (datafellows & SSH_BUG_SIGBLOB) { 58 error("ssh_rsa_sign: SSH_BUG_SIGBLOB not supported"); 59 return -1; 60 } 61 nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1; 62 if ((evp_md = EVP_get_digestbynid(nid)) == NULL) { 63 error("ssh_rsa_sign: EVP_get_digestbynid %d failed", nid); 64 return -1; 65 } 66 dlen = evp_md->md_size; 67 digest = xmalloc(dlen); 68 EVP_DigestInit(&md, evp_md); 69 EVP_DigestUpdate(&md, data, datalen); 70 EVP_DigestFinal(&md, digest, NULL); 71 72 slen = RSA_size(key->rsa); 73 sig = xmalloc(slen); 74 75 ok = RSA_sign(nid, digest, dlen, sig, &len, key->rsa); 76 memset(digest, 'd', dlen); 77 xfree(digest); 78 79 if (ok != 1) { 80 int ecode = ERR_get_error(); 81 error("ssh_rsa_sign: RSA_sign failed: %s", ERR_error_string(ecode, NULL)); 82 xfree(sig); 83 return -1; 84 } 85 if (len < slen) { 86 int diff = slen - len; 87 debug("slen %d > len %d", slen, len); 88 memmove(sig + diff, sig, len); 89 memset(sig, 0, diff); 90 } else if (len > slen) { 91 error("ssh_rsa_sign: slen %d slen2 %d", slen, len); 92 xfree(sig); 93 return -1; 94 } 95 /* encode signature */ 96 buffer_init(&b); 97 buffer_put_cstring(&b, "ssh-rsa"); 98 buffer_put_string(&b, sig, slen); 99 len = buffer_len(&b); 100 ret = xmalloc(len); 101 memcpy(ret, buffer_ptr(&b), len); 102 buffer_free(&b); 103 memset(sig, 's', slen); 104 xfree(sig); 105 106 if (lenp != NULL) 107 *lenp = len; 108 if (sigp != NULL) 109 *sigp = ret; 110 return 0; 111 } 112 113 int 114 ssh_rsa_verify( 115 Key *key, 116 u_char *signature, int signaturelen, 117 u_char *data, int datalen) 118 { 119 Buffer b; 120 const EVP_MD *evp_md; 121 EVP_MD_CTX md; 122 char *ktype; 123 u_char *sigblob, *digest; 124 u_int len, dlen; 125 int rlen, ret, nid; 126 127 if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) { 128 error("ssh_rsa_verify: no RSA key"); 129 return -1; 130 } 131 if (datafellows & SSH_BUG_SIGBLOB) { 132 error("ssh_rsa_verify: SSH_BUG_SIGBLOB not supported"); 133 return -1; 134 } 135 if (BN_num_bits(key->rsa->n) < 768) { 136 error("ssh_rsa_verify: n too small: %d bits", 137 BN_num_bits(key->rsa->n)); 138 return -1; 139 } 140 buffer_init(&b); 141 buffer_append(&b, signature, signaturelen); 142 ktype = buffer_get_string(&b, NULL); 143 if (strcmp("ssh-rsa", ktype) != 0) { 144 error("ssh_rsa_verify: cannot handle type %s", ktype); 145 buffer_free(&b); 146 xfree(ktype); 147 return -1; 148 } 149 xfree(ktype); 150 sigblob = buffer_get_string(&b, &len); 151 rlen = buffer_len(&b); 152 buffer_free(&b); 153 if (rlen != 0) { 154 error("ssh_rsa_verify: remaining bytes in signature %d", rlen); 155 xfree(sigblob); 156 return -1; 157 } 158 nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1; 159 if ((evp_md = EVP_get_digestbynid(nid)) == NULL) { 160 error("ssh_rsa_verify: EVP_get_digestbynid %d failed", nid); 161 xfree(sigblob); 162 return -1; 163 } 164 dlen = evp_md->md_size; 165 digest = xmalloc(dlen); 166 EVP_DigestInit(&md, evp_md); 167 EVP_DigestUpdate(&md, data, datalen); 168 EVP_DigestFinal(&md, digest, NULL); 169 170 ret = RSA_verify(nid, digest, dlen, sigblob, len, key->rsa); 171 memset(digest, 'd', dlen); 172 xfree(digest); 173 memset(sigblob, 's', len); 174 xfree(sigblob); 175 if (ret == 0) { 176 int ecode = ERR_get_error(); 177 error("ssh_rsa_verify: RSA_verify failed: %s", ERR_error_string(ecode, NULL)); 178 } 179 debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : ""); 180 return ret; 181 } 182