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Member "nettle-3.7.3/rsa-decrypt.c" (6 Jun 2021, 1718 Bytes) of package /linux/privat/nettle-3.7.3.tar.gz:


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    1 /* rsa-decrypt.c
    2 
    3    The RSA publickey algorithm. PKCS#1 encryption.
    4 
    5    Copyright (C) 2001, 2012 Niels Möller
    6 
    7    This file is part of GNU Nettle.
    8 
    9    GNU Nettle is free software: you can redistribute it and/or
   10    modify it under the terms of either:
   11 
   12      * the GNU Lesser General Public License as published by the Free
   13        Software Foundation; either version 3 of the License, or (at your
   14        option) any later version.
   15 
   16    or
   17 
   18      * the GNU General Public License as published by the Free
   19        Software Foundation; either version 2 of the License, or (at your
   20        option) any later version.
   21 
   22    or both in parallel, as here.
   23 
   24    GNU Nettle is distributed in the hope that it will be useful,
   25    but WITHOUT ANY WARRANTY; without even the implied warranty of
   26    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   27    General Public License for more details.
   28 
   29    You should have received copies of the GNU General Public License and
   30    the GNU Lesser General Public License along with this program.  If
   31    not, see http://www.gnu.org/licenses/.
   32 */
   33 
   34 #if HAVE_CONFIG_H
   35 # include "config.h"
   36 #endif
   37 
   38 #include "rsa.h"
   39 
   40 #include "pkcs1.h"
   41 
   42 int
   43 rsa_decrypt(const struct rsa_private_key *key,
   44         size_t *length, uint8_t *message,
   45         const mpz_t gibberish)
   46 {
   47   mpz_t m;
   48   int res;
   49 
   50   mpz_init(m);
   51 
   52   /* First check that input is in range. Since we don't have the
   53      public key available here, we need to reconstruct n. */
   54   mpz_mul (m, key->p, key->q);
   55   if (mpz_sgn (gibberish) < 0 || mpz_cmp (gibberish, m) >= 0)
   56     {
   57       mpz_clear (m);
   58       return 0;
   59     }
   60 
   61   rsa_compute_root(key, m, gibberish);
   62 
   63   res = pkcs1_decrypt (key->size, m, length, message);
   64   mpz_clear(m);
   65   return res;
   66 }