Annotation of src/usr.bin/ssh/ssh-rsa.c, Revision 1.25
1.1 markus 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"
1.25 ! markus 26: RCSID("$OpenBSD: ssh-rsa.c,v 1.24 2002/08/02 21:23:41 markus Exp $");
1.5 markus 27:
28: #include <openssl/evp.h>
29: #include <openssl/err.h>
1.1 markus 30:
31: #include "xmalloc.h"
1.5 markus 32: #include "log.h"
1.1 markus 33: #include "buffer.h"
34: #include "bufaux.h"
35: #include "key.h"
1.6 itojun 36: #include "ssh-rsa.h"
1.8 markus 37: #include "compat.h"
1.17 stevesk 38: #include "ssh.h"
1.1 markus 39:
1.25 ! markus 40: static int openssh_RSA_verify(int, u_char *, u_int, u_char *, u_int , RSA *);
! 41:
1.1 markus 42: /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
43: int
1.21 deraadt 44: ssh_rsa_sign(Key *key, u_char **sigp, u_int *lenp,
1.16 markus 45: u_char *data, u_int datalen)
1.1 markus 46: {
1.7 markus 47: const EVP_MD *evp_md;
1.1 markus 48: EVP_MD_CTX md;
1.23 markus 49: u_char digest[EVP_MAX_MD_SIZE], *sig;
1.2 markus 50: u_int slen, dlen, len;
1.7 markus 51: int ok, nid;
1.1 markus 52: Buffer b;
53:
54: if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) {
55: error("ssh_rsa_sign: no RSA key");
56: return -1;
57: }
1.8 markus 58: nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
1.7 markus 59: if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
60: error("ssh_rsa_sign: EVP_get_digestbynid %d failed", nid);
61: return -1;
62: }
1.1 markus 63: EVP_DigestInit(&md, evp_md);
64: EVP_DigestUpdate(&md, data, datalen);
1.15 markus 65: EVP_DigestFinal(&md, digest, &dlen);
1.1 markus 66:
1.7 markus 67: slen = RSA_size(key->rsa);
68: sig = xmalloc(slen);
69:
70: ok = RSA_sign(nid, digest, dlen, sig, &len, key->rsa);
1.15 markus 71: memset(digest, 'd', sizeof(digest));
1.1 markus 72:
73: if (ok != 1) {
74: int ecode = ERR_get_error();
1.21 deraadt 75: error("ssh_rsa_sign: RSA_sign failed: %s",
76: ERR_error_string(ecode, NULL));
1.1 markus 77: xfree(sig);
78: return -1;
79: }
80: if (len < slen) {
1.24 markus 81: u_int diff = slen - len;
1.21 deraadt 82: debug("slen %u > len %u", slen, len);
1.1 markus 83: memmove(sig + diff, sig, len);
84: memset(sig, 0, diff);
85: } else if (len > slen) {
1.21 deraadt 86: error("ssh_rsa_sign: slen %u slen2 %u", slen, len);
1.1 markus 87: xfree(sig);
88: return -1;
89: }
90: /* encode signature */
91: buffer_init(&b);
92: buffer_put_cstring(&b, "ssh-rsa");
93: buffer_put_string(&b, sig, slen);
94: len = buffer_len(&b);
1.23 markus 95: if (lenp != NULL)
96: *lenp = len;
97: if (sigp != NULL) {
98: *sigp = xmalloc(len);
99: memcpy(*sigp, buffer_ptr(&b), len);
100: }
1.1 markus 101: buffer_free(&b);
102: memset(sig, 's', slen);
103: xfree(sig);
104:
105: return 0;
106: }
107:
108: int
1.21 deraadt 109: ssh_rsa_verify(Key *key, u_char *signature, u_int signaturelen,
1.16 markus 110: u_char *data, u_int datalen)
1.1 markus 111: {
112: Buffer b;
1.7 markus 113: const EVP_MD *evp_md;
1.1 markus 114: EVP_MD_CTX md;
115: char *ktype;
1.15 markus 116: u_char digest[EVP_MAX_MD_SIZE], *sigblob;
1.19 markus 117: u_int len, dlen, modlen;
1.7 markus 118: int rlen, ret, nid;
1.1 markus 119:
120: if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) {
121: error("ssh_rsa_verify: no RSA key");
1.4 markus 122: return -1;
123: }
1.17 stevesk 124: if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) {
1.20 stevesk 125: error("ssh_rsa_verify: RSA modulus too small: %d < minimum %d bits",
126: BN_num_bits(key->rsa->n), SSH_RSA_MINIMUM_MODULUS_SIZE);
1.1 markus 127: return -1;
128: }
129: buffer_init(&b);
1.10 stevesk 130: buffer_append(&b, signature, signaturelen);
1.1 markus 131: ktype = buffer_get_string(&b, NULL);
132: if (strcmp("ssh-rsa", ktype) != 0) {
133: error("ssh_rsa_verify: cannot handle type %s", ktype);
134: buffer_free(&b);
135: xfree(ktype);
136: return -1;
137: }
138: xfree(ktype);
1.10 stevesk 139: sigblob = buffer_get_string(&b, &len);
1.1 markus 140: rlen = buffer_len(&b);
141: buffer_free(&b);
1.14 deraadt 142: if (rlen != 0) {
1.12 markus 143: error("ssh_rsa_verify: remaining bytes in signature %d", rlen);
1.7 markus 144: xfree(sigblob);
1.1 markus 145: return -1;
1.19 markus 146: }
147: /* RSA_verify expects a signature of RSA_size */
148: modlen = RSA_size(key->rsa);
149: if (len > modlen) {
1.21 deraadt 150: error("ssh_rsa_verify: len %u > modlen %u", len, modlen);
1.19 markus 151: xfree(sigblob);
152: return -1;
153: } else if (len < modlen) {
1.24 markus 154: u_int diff = modlen - len;
1.21 deraadt 155: debug("ssh_rsa_verify: add padding: modlen %u > len %u",
1.19 markus 156: modlen, len);
157: sigblob = xrealloc(sigblob, modlen);
158: memmove(sigblob + diff, sigblob, len);
159: memset(sigblob, 0, diff);
160: len = modlen;
1.1 markus 161: }
1.8 markus 162: nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
1.7 markus 163: if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
1.12 markus 164: error("ssh_rsa_verify: EVP_get_digestbynid %d failed", nid);
1.7 markus 165: xfree(sigblob);
166: return -1;
167: }
1.1 markus 168: EVP_DigestInit(&md, evp_md);
169: EVP_DigestUpdate(&md, data, datalen);
1.15 markus 170: EVP_DigestFinal(&md, digest, &dlen);
1.1 markus 171:
1.25 ! markus 172: ret = openssh_RSA_verify(nid, digest, dlen, sigblob, len, key->rsa);
1.15 markus 173: memset(digest, 'd', sizeof(digest));
1.1 markus 174: memset(sigblob, 's', len);
175: xfree(sigblob);
176: debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : "");
1.25 ! markus 177: return ret;
! 178: }
! 179:
! 180: /*
! 181: * See:
! 182: * http://www.rsasecurity.com/rsalabs/pkcs/pkcs-1/
! 183: * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.asn
! 184: */
! 185: /*
! 186: * id-sha1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
! 187: * oiw(14) secsig(3) algorithms(2) 26 }
! 188: */
! 189: static const u_char id_sha1[] = {
! 190: 0x30, 0x21, /* type Sequence, length 0x21 (33) */
! 191: 0x30, 0x09, /* type Sequence, length 0x09 */
! 192: 0x06, 0x05, /* type OID, length 0x05 */
! 193: 0x2b, 0x0e, 0x03, 0x02, 0x1a, /* id-sha1 OID */
! 194: 0x05, 0x00, /* NULL */
! 195: 0x04, 0x14 /* Octet string, length 0x14 (20), followed by sha1 hash */
! 196: };
! 197: /*
! 198: * id-md5 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
! 199: * rsadsi(113549) digestAlgorithm(2) 5 }
! 200: */
! 201: static const u_char id_md5[] = {
! 202: 0x30, 0x20, /* type Sequence, length 0x20 (32) */
! 203: 0x30, 0x0c, /* type Sequence, length 0x09 */
! 204: 0x06, 0x08, /* type OID, length 0x05 */
! 205: 0x2a, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x02, 0x05, /* id-md5 */
! 206: 0x05, 0x00, /* NULL */
! 207: 0x04, 0x10 /* Octet string, length 0x10 (16), followed by md5 hash */
! 208: };
! 209:
! 210: static int
! 211: openssh_RSA_verify(int type, u_char *hash, u_int hashlen,
! 212: u_char *sigbuf, u_int siglen, RSA *rsa)
! 213: {
! 214: u_int ret, rsasize, len, oidlen = 0, hlen = 0;
! 215: const u_char *oid = NULL;
! 216: u_char *decrypted = NULL;
! 217:
! 218: ret = 0;
! 219: switch (type) {
! 220: case NID_sha1:
! 221: oid = id_sha1;
! 222: oidlen = sizeof(id_sha1);
! 223: hlen = 20;
! 224: break;
! 225: case NID_md5:
! 226: oid = id_md5;
! 227: oidlen = sizeof(id_md5);
! 228: hlen = 16;
! 229: break;
! 230: default:
! 231: goto done;
! 232: break;
! 233: }
! 234: if (hashlen != hlen) {
! 235: error("bad hashlen");
! 236: goto done;
! 237: }
! 238: rsasize = RSA_size(rsa);
! 239: if (siglen == 0 || siglen > rsasize) {
! 240: error("bad siglen");
! 241: goto done;
! 242: }
! 243: decrypted = xmalloc(rsasize);
! 244: if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa,
! 245: RSA_PKCS1_PADDING)) < 0) {
! 246: error("RSA_public_decrypt failed: %s",
! 247: ERR_error_string(ERR_get_error(), NULL));
! 248: goto done;
! 249: }
! 250: if (len != hlen + oidlen) {
! 251: error("bad decrypted len: %d != %d + %d", len, hlen, oidlen);
! 252: goto done;
! 253: }
! 254: if (memcmp(decrypted, oid, oidlen) != 0) {
! 255: error("oid mismatch");
! 256: goto done;
! 257: }
! 258: if (memcmp(decrypted + oidlen, hash, hlen) != 0) {
! 259: error("hash mismatch");
! 260: goto done;
! 261: }
! 262: ret = 1;
! 263: done:
! 264: if (decrypted)
! 265: xfree(decrypted);
1.1 markus 266: return ret;
267: }
![[BACK]](/icons/back.gif){kind=icon}
Return to ssh-rsa.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh