1 /* $OpenBSD: rsa.c,v 1.29 2006/11/06 21:25:28 markus Exp $ */
2 /*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * All rights reserved
6 *
7 * As far as I am concerned, the code I have written for this software
8 * can be used freely for any purpose. Any derived versions of this
9 * software must be clearly marked as such, and if the derived work is
10 * incompatible with the protocol description in the RFC file, it must be
11 * called by a name other than "ssh" or "Secure Shell".
12 *
13 *
14 * Copyright (c) 1999 Niels Provos. All rights reserved.
15 *
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
18 * are met:
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer.
21 * 2. Redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35 *
36 *
37 * Description of the RSA algorithm can be found e.g. from the following
38 * sources:
39 *
40 * Bruce Schneier: Applied Cryptography. John Wiley & Sons, 1994.
41 *
42 * Jennifer Seberry and Josed Pieprzyk: Cryptography: An Introduction to
43 * Computer Security. Prentice-Hall, 1989.
44 *
45 * Man Young Rhee: Cryptography and Secure Data Communications. McGraw-Hill,
46 * 1994.
47 *
48 * R. Rivest, A. Shamir, and L. M. Adleman: Cryptographic Communications
49 * System and Method. US Patent 4,405,829, 1983.
50 *
51 * Hans Riesel: Prime Numbers and Computer Methods for Factorization.
52 * Birkhauser, 1994.
53 *
54 * The RSA Frequently Asked Questions document by RSA Data Security,
55 * Inc., 1995.
56 *
57 * RSA in 3 lines of perl by Adam Back <aba@atlax.ex.ac.uk>, 1995, as
58 * included below:
59 *
60 * [gone - had to be deleted - what a pity]
61 */
62
63 #include <sys/types.h>
64
65 #include <string.h>
66
67 #include "xmalloc.h"
68 #include "rsa.h"
69 #include "log.h"
70
71 void
rsa_public_encrypt(BIGNUM * out,BIGNUM * in,RSA * key)72 rsa_public_encrypt(BIGNUM *out, BIGNUM *in, RSA *key)
73 {
74 u_char *inbuf, *outbuf;
75 int len, ilen, olen;
76
77 if (BN_num_bits(key->e) < 2 || !BN_is_odd(key->e))
78 fatal("rsa_public_encrypt() exponent too small or not odd");
79
80 olen = BN_num_bytes(key->n);
81 outbuf = xmalloc(olen);
82
83 ilen = BN_num_bytes(in);
84 inbuf = xmalloc(ilen);
85 BN_bn2bin(in, inbuf);
86
87 if ((len = RSA_public_encrypt(ilen, inbuf, outbuf, key,
88 RSA_PKCS1_PADDING)) <= 0)
89 fatal("rsa_public_encrypt() failed");
90
91 if (BN_bin2bn(outbuf, len, out) == NULL)
92 fatal("rsa_public_encrypt: BN_bin2bn failed");
93
94 memset(outbuf, 0, olen);
95 memset(inbuf, 0, ilen);
96 xfree(outbuf);
97 xfree(inbuf);
98 }
99
100 int
rsa_private_decrypt(BIGNUM * out,BIGNUM * in,RSA * key)101 rsa_private_decrypt(BIGNUM *out, BIGNUM *in, RSA *key)
102 {
103 u_char *inbuf, *outbuf;
104 int len, ilen, olen;
105
106 olen = BN_num_bytes(key->n);
107 outbuf = xmalloc(olen);
108
109 ilen = BN_num_bytes(in);
110 inbuf = xmalloc(ilen);
111 BN_bn2bin(in, inbuf);
112
113 if ((len = RSA_private_decrypt(ilen, inbuf, outbuf, key,
114 RSA_PKCS1_PADDING)) <= 0) {
115 error("rsa_private_decrypt() failed");
116 } else {
117 if (BN_bin2bn(outbuf, len, out) == NULL)
118 fatal("rsa_private_decrypt: BN_bin2bn failed");
119 }
120 memset(outbuf, 0, olen);
121 memset(inbuf, 0, ilen);
122 xfree(outbuf);
123 xfree(inbuf);
124 return len;
125 }
126
127 /* calculate p-1 and q-1 */
128 void
rsa_generate_additional_parameters(RSA * rsa)129 rsa_generate_additional_parameters(RSA *rsa)
130 {
131 BIGNUM *aux;
132 BN_CTX *ctx;
133
134 if ((aux = BN_new()) == NULL)
135 fatal("rsa_generate_additional_parameters: BN_new failed");
136 if ((ctx = BN_CTX_new()) == NULL)
137 fatal("rsa_generate_additional_parameters: BN_CTX_new failed");
138
139 if ((BN_sub(aux, rsa->q, BN_value_one()) == 0) ||
140 (BN_mod(rsa->dmq1, rsa->d, aux, ctx) == 0) ||
141 (BN_sub(aux, rsa->p, BN_value_one()) == 0) ||
142 (BN_mod(rsa->dmp1, rsa->d, aux, ctx) == 0))
143 fatal("rsa_generate_additional_parameters: BN_sub/mod failed");
144
145 BN_clear_free(aux);
146 BN_CTX_free(ctx);
147 }
148
149