rsa.c

   1 /* $OpenBSD: rsa.c,v 1.28 2006/08/03 03:34:42 deraadt 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 <string.h>
  68
  69 #include "xmalloc.h"
  70 #include "rsa.h"
  71 #include "log.h"
  72
  73 void
  74 rsa_public_encrypt(BIGNUM *out, BIGNUM *in, RSA *key)
  75 {
  76         u_char *inbuf, *outbuf;
  77         int len, ilen, olen;
  78
  79         if (BN_num_bits(key->e) < 2 || !BN_is_odd(key->e))
  80                 fatal("rsa_public_encrypt() exponent too small or not odd");
  81
  82         olen = BN_num_bytes(key->n);
  83         outbuf = xmalloc(olen);
  84
  85         ilen = BN_num_bytes(in);
  86         inbuf = xmalloc(ilen);
  87         BN_bn2bin(in, inbuf);
  88
  89         if ((len = RSA_public_encrypt(ilen, inbuf, outbuf, key,
  90             RSA_PKCS1_PADDING)) <= 0)
  91                 fatal("rsa_public_encrypt() failed");
  92
  93         BN_bin2bn(outbuf, len, out);
  94
  95         memset(outbuf, 0, olen);
  96         memset(inbuf, 0, ilen);
  97         xfree(outbuf);
  98         xfree(inbuf);
  99 }
 100
 101 int
 102 rsa_private_decrypt(BIGNUM *out, BIGNUM *in, RSA *key)
 103 {
 104         u_char *inbuf, *outbuf;
 105         int len, ilen, olen;
 106
 107         olen = BN_num_bytes(key->n);
 108         outbuf = xmalloc(olen);
 109
 110         ilen = BN_num_bytes(in);
 111         inbuf = xmalloc(ilen);
 112         BN_bn2bin(in, inbuf);
 113
 114         if ((len = RSA_private_decrypt(ilen, inbuf, outbuf, key,
 115             RSA_PKCS1_PADDING)) <= 0) {
 116                 error("rsa_private_decrypt() failed");
 117         } else {
 118                 BN_bin2bn(outbuf, len, out);
 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
 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         BN_sub(aux, rsa->q, BN_value_one());
 140         BN_mod(rsa->dmq1, rsa->d, aux, ctx);
 141
 142         BN_sub(aux, rsa->p, BN_value_one());
 143         BN_mod(rsa->dmp1, rsa->d, aux, ctx);
 144
 145         BN_clear_free(aux);
 146         BN_CTX_free(ctx);
 147 }
 148