git.distorted.org.uk Git - u/mdw/catacomb/blob - rsa-pub.c

   1 /* -*-c-*-
   2  *
   3  * $Id: rsa-pub.c,v 1.2 2000/10/08 16:00:32 mdw Exp $
   4  *
   5  * [RSA encryption with padding *
   6  * (c) 2000 Straylight/Edgeware
   7  */
   8
   9 /*----- Licensing notice --------------------------------------------------*
  10  *
  11  * This file is part of Catacomb.
  12  *
  13  * Catacomb is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU Library General Public License as
  15  * published by the Free Software Foundation; either version 2 of the
  16  * License, or (at your option) any later version.
  17  *
  18  * Catacomb is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  * GNU Library General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU Library General Public
  24  * License along with Catacomb; if not, write to the Free
  25  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  26  * MA 02111-1307, USA.
  27  */
  28
  29 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: rsa-pub.c,v $
  32  * Revision 1.2  2000/10/08 16:00:32  mdw
  33  * Fix compiler warning.
  34  *
  35  * Revision 1.1  2000/07/01 11:23:52  mdw
  36  * Public-key operations, for symmetry with `rsa-priv.c'.  Functions for
  37  * doing padded RSA encryption and signature verification.
  38  *
  39  */
  40
  41 /*----- Header files ------------------------------------------------------*/
  42
  43 #include <mLib/alloc.h>
  44 #include <mLib/bits.h>
  45 #include <mLib/dstr.h>
  46
  47 #include "mp.h"
  48 #include "mpmont.h"
  49 #include "rsa.h"
  50
  51 /*----- Public key operations ---------------------------------------------*/
  52
  53 /* --- @rsa_pubcreate@ --- *
  54  *
  55  * Arguments:   @rsa_pubctx *rd@ = pointer to an RSA public key context
  56  *              @rsa_pub *rp@ = pointer to RSA public key
  57  *
  58  * Returns:     ---
  59  *
  60  * Use:         Initializes an RSA public-key context.
  61  */
  62
  63 void rsa_pubcreate(rsa_pubctx *rd, rsa_pub *rp)
  64 {
  65   rd->rp = rp;
  66   mpmont_create(&rd->mm, rp->n);
  67 }
  68
  69 /* --- @rsa_pubdestroy@ --- *
  70  *
  71  * Arguments:   @rsa_pubctx *rd@ = pointer to an RSA public key context
  72  *
  73  * Returns:     ---
  74  *
  75  * Use:         Destroys an RSA public-key context.
  76  */
  77
  78 void rsa_pubdestroy(rsa_pubctx *rd)
  79 {
  80   mpmont_destroy(&rd->mm);
  81 }
  82
  83 /* --- @rsa_pubop@ --- *
  84  *
  85  * Arguments:   @rsa_pubctx *rd@ = pointer to an RSA public key context
  86  *              @mp *d@ = destination
  87  *              @mp *p@ = input message
  88  *
  89  * Returns:     The transformed output message.
  90  *
  91  * Use:         Performs an RSA public key operation.
  92  */
  93
  94 mp *rsa_pubop(rsa_pubctx *rd, mp *d, mp *p)
  95 {
  96   return (mpmont_exp(&rd->mm, d, p, rd->rp->e));
  97 }
  98
  99 /* --- @rsa_qpubop@ --- *
 100  *
 101  * Arguments:   @rsa_pub *rp@ = pointer to RSA parameters
 102  *              @mp *d@ = destination
 103  *              @mp *p@ = input message
 104  *
 105  * Returns:     Correctly transformed output message.
 106  *
 107  * Use:         Performs an RSA public key operation.
 108  */
 109
 110 mp *rsa_qpubop(rsa_pub *rp, mp *d, mp *c)
 111 {
 112   rsa_pubctx rd;
 113   rsa_pubcreate(&rd, rp);
 114   d = rsa_pubop(&rd, d, c);
 115   rsa_pubdestroy(&rd);
 116   return (d);
 117 }
 118
 119 /*----- Operations with padding -------------------------------------------*/
 120
 121 /* --- @rsa_encrypt@ --- *
 122  *
 123  * Arguments:   @rsa_pubctx *rp@ = pointer to an RSA public key context
 124  *              @const void *m@ = pointer to input message
 125  *              @size_t sz@ = size of input message
 126  *              @dstr *d@ = pointer to output string
 127  *              @rsa_encodeproc e@ = encoding procedure
 128  *              @void *earg@ = argument pointer for encoding procedure
 129  *
 130  * Returns:     The length of the output string if successful, negative on
 131  *              failure.
 132  *
 133  * Use:         Does RSA encryption.
 134  */
 135
 136 int rsa_encrypt(rsa_pubctx *rp, const void *m, size_t sz,
 137                 dstr *d, rsa_encodeproc e, void *earg)
 138 {
 139   mp *x;
 140   size_t n = mp_octets(rp->rp->n);
 141   octet *p;
 142   int rc;
 143
 144   /* --- Sort out some space --- */
 145
 146   dstr_ensure(d, n);
 147   p = (octet *)d->buf + d->len;
 148   p[0] = 0;
 149
 150   /* --- Do the packing --- */
 151
 152   if ((rc = e(m, sz, p, n, earg)) < 0)
 153     return (rc);
 154
 155   /* --- Do the encryption --- */
 156
 157   x = mp_loadb(MP_NEWSEC, p, n);
 158   x = rsa_pubop(rp, x, x);
 159   mp_storeb(x, p, n);
 160   d->len += n;
 161   mp_drop(x);
 162   return (n);
 163 }
 164
 165 /* --- @rsa_verify@ --- *
 166  *
 167  * Arguments:   @rsa_pubctx *rp@ = pointer to an RSA public key context
 168  *              @const void *m@ = pointer to input message
 169  *              @size_t sz@ = size of input message
 170  *              @dstr *d@ = pointer to output string
 171  *              @rsa_decodeproc e@ = decoding procedure
 172  *              @void *earg@ = argument pointer for decoding procedure
 173  *
 174  * Returns:     The length of the output string if successful, negative on
 175  *              failure.
 176  *
 177  * Use:         Does RSA signature verification.
 178  */
 179
 180 int rsa_verify(rsa_pubctx *rp, const void *m, size_t sz,
 181                dstr *d, rsa_decodeproc e, void *earg)
 182 {
 183   mp *x;
 184   size_t n = mp_octets(rp->rp->n);
 185   octet *p;
 186   int rc;
 187
 188   /* --- Do the exponentiation --- */
 189
 190   p = x_alloc(d->a, n);
 191   x = mp_loadb(MP_NEW, m, sz);
 192   x = rsa_pubop(rp, x, x);
 193   mp_storeb(x, p, n);
 194   mp_drop(x);
 195
 196   /* --- Do the decoding --- */
 197
 198   rc = e(p, n, d, earg);
 199   x_free(d->a, p);
 200   return (rc);
 201 }
 202
 203 /*----- That's all, folks -------------------------------------------------*/