Annotation of src/usr.bin/ssh/ssh-rsa.c, Revision 1.5
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"
1.5 ! markus 26: RCSID("$OpenBSD: ssh-rsa.c,v 1.4 2001/01/16 19:20:06 markus Exp $");
! 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"
36:
37: /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
38: int
39: ssh_rsa_sign(
40: Key *key,
1.2 markus 41: u_char **sigp, int *lenp,
42: u_char *data, int datalen)
1.1 markus 43: {
44: EVP_MD *evp_md = EVP_sha1();
45: EVP_MD_CTX md;
1.2 markus 46: u_char *digest, *sig, *ret;
47: u_int slen, dlen, len;
1.1 markus 48: int ok;
49: Buffer b;
50:
51: if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) {
52: error("ssh_rsa_sign: no RSA key");
53: return -1;
54: }
55: slen = RSA_size(key->rsa);
56: sig = xmalloc(slen);
57:
58: dlen = evp_md->md_size;
59: digest = xmalloc(dlen);
60: EVP_DigestInit(&md, evp_md);
61: EVP_DigestUpdate(&md, data, datalen);
62: EVP_DigestFinal(&md, digest, NULL);
63:
64: ok = RSA_sign(NID_sha1, digest, dlen, sig, &len, key->rsa);
65: memset(digest, 'd', dlen);
66: xfree(digest);
67:
68: if (ok != 1) {
69: int ecode = ERR_get_error();
70: error("ssh_rsa_sign: RSA_sign failed: %s", ERR_error_string(ecode, NULL));
71: xfree(sig);
72: return -1;
73: }
74: if (len < slen) {
75: int diff = slen - len;
76: debug("slen %d > len %d", slen, len);
77: memmove(sig + diff, sig, len);
78: memset(sig, 0, diff);
79: } else if (len > slen) {
80: error("ssh_rsa_sign: slen %d slen2 %d", slen, len);
81: xfree(sig);
82: return -1;
83: }
84: /* encode signature */
85: buffer_init(&b);
86: buffer_put_cstring(&b, "ssh-rsa");
87: buffer_put_string(&b, sig, slen);
88: len = buffer_len(&b);
89: ret = xmalloc(len);
90: memcpy(ret, buffer_ptr(&b), len);
91: buffer_free(&b);
92: memset(sig, 's', slen);
93: xfree(sig);
94:
95: if (lenp != NULL)
96: *lenp = len;
97: if (sigp != NULL)
98: *sigp = ret;
99: debug2("ssh_rsa_sign: done");
100: return 0;
101: }
102:
103: int
104: ssh_rsa_verify(
105: Key *key,
1.2 markus 106: u_char *signature, int signaturelen,
107: u_char *data, int datalen)
1.1 markus 108: {
109: Buffer b;
110: EVP_MD *evp_md = EVP_sha1();
111: EVP_MD_CTX md;
112: char *ktype;
1.2 markus 113: u_char *sigblob, *digest;
114: u_int len, dlen;
1.1 markus 115: int rlen;
116: int ret;
117:
118: if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) {
119: error("ssh_rsa_verify: no RSA key");
1.4 markus 120: return -1;
121: }
122: if (BN_num_bits(key->rsa->n) < 768) {
123: error("ssh_rsa_verify: n too small: %d bits",
124: BN_num_bits(key->rsa->n));
1.1 markus 125: return -1;
126: }
127: buffer_init(&b);
128: buffer_append(&b, (char *) signature, signaturelen);
129: ktype = buffer_get_string(&b, NULL);
130: if (strcmp("ssh-rsa", ktype) != 0) {
131: error("ssh_rsa_verify: cannot handle type %s", ktype);
132: buffer_free(&b);
133: xfree(ktype);
134: return -1;
135: }
136: xfree(ktype);
1.2 markus 137: sigblob = (u_char *)buffer_get_string(&b, &len);
1.1 markus 138: rlen = buffer_len(&b);
139: buffer_free(&b);
140: if(rlen != 0) {
141: error("ssh_rsa_verify: remaining bytes in signature %d", rlen);
142: return -1;
143: }
144:
145: dlen = evp_md->md_size;
146: digest = xmalloc(dlen);
147: EVP_DigestInit(&md, evp_md);
148: EVP_DigestUpdate(&md, data, datalen);
149: EVP_DigestFinal(&md, digest, NULL);
150:
151: ret = RSA_verify(NID_sha1, digest, dlen, sigblob, len, key->rsa);
152: memset(digest, 'd', dlen);
153: xfree(digest);
154: memset(sigblob, 's', len);
155: xfree(sigblob);
156: if (ret == 0) {
157: int ecode = ERR_get_error();
158: error("ssh_rsa_verify: RSA_verify failed: %s", ERR_error_string(ecode, NULL));
159: }
160: debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : "");
161: return ret;
162: }
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