rsa.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  *
   6  * As far as I am concerned, the code I have written for this software
   7  * can be used freely for any purpose.  Any derived versions of this
   8  * software must be clearly marked as such, and if the derived work is
   9  * incompatible with the protocol description in the RFC file, it must be
  10  * called by a name other than "ssh" or "Secure Shell".
  11  *
  12  *
  13  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  14  *
  15  * Redistribution and use in source and binary forms, with or without
  16  * modification, are permitted provided that the following conditions
  17  * are met:
  18  * 1. Redistributions of source code must retain the above copyright
  19  *    notice, this list of conditions and the following disclaimer.
  20  * 2. Redistributions in binary form must reproduce the above copyright
  21  *    notice, this list of conditions and the following disclaimer in the
  22  *    documentation and/or other materials provided with the distribution.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  27  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  28  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  29  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  30  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  31  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  32  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  33  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  34  *
  35  *
  36  * Description of the RSA algorithm can be found e.g. from the following
  37  * sources:
  38  *
  39  *   Bruce Schneier: Applied Cryptography.  John Wiley & Sons, 1994.
  40  *
  41  *   Jennifer Seberry and Josed Pieprzyk: Cryptography: An Introduction to
  42  *   Computer Security.  Prentice-Hall, 1989.
  43  *
  44  *   Man Young Rhee: Cryptography and Secure Data Communications.  McGraw-Hill,
  45  *   1994.
  46  *
  47  *   R. Rivest, A. Shamir, and L. M. Adleman: Cryptographic Communications
  48  *   System and Method.  US Patent 4,405,829, 1983.
  49  *
  50  *   Hans Riesel: Prime Numbers and Computer Methods for Factorization.
  51  *   Birkhauser, 1994.
  52  *
  53  *   The RSA Frequently Asked Questions document by RSA Data Security,
  54  *   Inc., 1995.
  55  *
  56  *   RSA in 3 lines of perl by Adam Back <aba@atlax.ex.ac.uk>, 1995, as
  57  * included below:
  58  *
  59  *     [gone - had to be deleted - what a pity]
  60  */
  61
  62 #include "includes.h"
  63 RCSID("$OpenBSD: rsa.c,v 1.24 2001/12/27 18:22:16 markus Exp $");
  64
  65 #include "rsa.h"
  66 #include "log.h"
  67 #include "xmalloc.h"
  68
  69 void
  70 rsa_public_encrypt(BIGNUM *out, BIGNUM *in, RSA *key)
  71 {
  72         u_char *inbuf, *outbuf;
  73         int len, ilen, olen;
  74
  75         if (BN_num_bits(key->e) < 2 || !BN_is_odd(key->e))
  76                 fatal("rsa_public_encrypt() exponent too small or not odd");
  77
  78         olen = BN_num_bytes(key->n);
  79         outbuf = xmalloc(olen);
  80
  81         ilen = BN_num_bytes(in);
  82         inbuf = xmalloc(ilen);
  83         BN_bn2bin(in, inbuf);
  84
  85         if ((len = RSA_public_encrypt(ilen, inbuf, outbuf, key,
  86             RSA_PKCS1_PADDING)) <= 0)
  87                 fatal("rsa_public_encrypt() failed");
  88
  89         BN_bin2bn(outbuf, len, out);
  90
  91         memset(outbuf, 0, olen);
  92         memset(inbuf, 0, ilen);
  93         xfree(outbuf);
  94         xfree(inbuf);
  95 }
  96
  97 int
  98 rsa_private_decrypt(BIGNUM *out, BIGNUM *in, RSA *key)
  99 {
 100         u_char *inbuf, *outbuf;
 101         int len, ilen, olen;
 102
 103         olen = BN_num_bytes(key->n);
 104         outbuf = xmalloc(olen);
 105
 106         ilen = BN_num_bytes(in);
 107         inbuf = xmalloc(ilen);
 108         BN_bn2bin(in, inbuf);
 109
 110         if ((len = RSA_private_decrypt(ilen, inbuf, outbuf, key,
 111             RSA_PKCS1_PADDING)) <= 0) {
 112                 error("rsa_private_decrypt() failed");
 113         } else {
 114                 BN_bin2bn(outbuf, len, out);
 115         }
 116         memset(outbuf, 0, olen);
 117         memset(inbuf, 0, ilen);
 118         xfree(outbuf);
 119         xfree(inbuf);
 120         return len;
 121 }
 122
 123 /* calculate p-1 and q-1 */
 124 void
 125 rsa_generate_additional_parameters(RSA *rsa)
 126 {
 127         BIGNUM *aux;
 128         BN_CTX *ctx;
 129
 130         if ((aux = BN_new()) == NULL)
 131                 fatal("rsa_generate_additional_parameters: BN_new failed");
 132         if ((ctx = BN_CTX_new()) == NULL)
 133                 fatal("rsa_generate_additional_parameters: BN_CTX_new failed");
 134
 135         BN_sub(aux, rsa->q, BN_value_one());
 136         BN_mod(rsa->dmq1, rsa->d, aux, ctx);
 137
 138         BN_sub(aux, rsa->p, BN_value_one());
 139         BN_mod(rsa->dmp1, rsa->d, aux, ctx);
 140
 141         BN_clear_free(aux);
 142         BN_CTX_free(ctx);
 143 }
 144