rsa.c revision 264377 
1/* $OpenBSD: rsa.c,v 1.31 2014/02/02 03:44:31 djm 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 "includes.h"
64
65#include <sys/types.h>
66
67#include <stdarg.h>
68#include <string.h>
69
70#include "xmalloc.h"
71#include "rsa.h"
72#include "log.h"
73
74void
75rsa_public_encrypt(BIGNUM *out, BIGNUM *in, RSA *key)
76{
77	u_char *inbuf, *outbuf;
78	int len, ilen, olen;
79
80	if (BN_num_bits(key->e) < 2 || !BN_is_odd(key->e))
81		fatal("rsa_public_encrypt() exponent too small or not odd");
82
83	olen = BN_num_bytes(key->n);
84	outbuf = xmalloc(olen);
85
86	ilen = BN_num_bytes(in);
87	inbuf = xmalloc(ilen);
88	BN_bn2bin(in, inbuf);
89
90	if ((len = RSA_public_encrypt(ilen, inbuf, outbuf, key,
91	    RSA_PKCS1_PADDING)) <= 0)
92		fatal("rsa_public_encrypt() failed");
93
94	if (BN_bin2bn(outbuf, len, out) == NULL)
95		fatal("rsa_public_encrypt: BN_bin2bn failed");
96
97	explicit_bzero(outbuf, olen);
98	explicit_bzero(inbuf, ilen);
99	free(outbuf);
100	free(inbuf);
101}
102
103int
104rsa_private_decrypt(BIGNUM *out, BIGNUM *in, RSA *key)
105{
106	u_char *inbuf, *outbuf;
107	int len, ilen, olen;
108
109	olen = BN_num_bytes(key->n);
110	outbuf = xmalloc(olen);
111
112	ilen = BN_num_bytes(in);
113	inbuf = xmalloc(ilen);
114	BN_bn2bin(in, inbuf);
115
116	if ((len = RSA_private_decrypt(ilen, inbuf, outbuf, key,
117	    RSA_PKCS1_PADDING)) <= 0) {
118		error("rsa_private_decrypt() failed");
119	} else {
120		if (BN_bin2bn(outbuf, len, out) == NULL)
121			fatal("rsa_private_decrypt: BN_bin2bn failed");
122	}
123	explicit_bzero(outbuf, olen);
124	explicit_bzero(inbuf, ilen);
125	free(outbuf);
126	free(inbuf);
127	return len;
128}
129
130/* calculate p-1 and q-1 */
131void
132rsa_generate_additional_parameters(RSA *rsa)
133{
134	BIGNUM *aux;
135	BN_CTX *ctx;
136
137	if ((aux = BN_new()) == NULL)
138		fatal("rsa_generate_additional_parameters: BN_new failed");
139	if ((ctx = BN_CTX_new()) == NULL)
140		fatal("rsa_generate_additional_parameters: BN_CTX_new failed");
141
142	if ((BN_sub(aux, rsa->q, BN_value_one()) == 0) ||
143	    (BN_mod(rsa->dmq1, rsa->d, aux, ctx) == 0) ||
144	    (BN_sub(aux, rsa->p, BN_value_one()) == 0) ||
145	    (BN_mod(rsa->dmp1, rsa->d, aux, ctx) == 0))
146		fatal("rsa_generate_additional_parameters: BN_sub/mod failed");
147
148	BN_clear_free(aux);
149	BN_CTX_free(ctx);
150}
151
152