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Member "nettle-3.7.3/rsa-decrypt-tr.c" (6 Jun 2021, 2131 Bytes) of package /linux/privat/nettle-3.7.3.tar.gz:


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    1 /* rsa-decrypt-tr.c
    2 
    3    RSA decryption, using randomized RSA blinding to be more resistant
    4    to timing attacks.
    5 
    6    Copyright (C) 2001, 2012 Niels Möller, Nikos Mavrogiannopoulos
    7 
    8    This file is part of GNU Nettle.
    9 
   10    GNU Nettle is free software: you can redistribute it and/or
   11    modify it under the terms of either:
   12 
   13      * the GNU Lesser General Public License as published by the Free
   14        Software Foundation; either version 3 of the License, or (at your
   15        option) any later version.
   16 
   17    or
   18 
   19      * the GNU General Public License as published by the Free
   20        Software Foundation; either version 2 of the License, or (at your
   21        option) any later version.
   22 
   23    or both in parallel, as here.
   24 
   25    GNU Nettle is distributed in the hope that it will be useful,
   26    but WITHOUT ANY WARRANTY; without even the implied warranty of
   27    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   28    General Public License for more details.
   29 
   30    You should have received copies of the GNU General Public License and
   31    the GNU Lesser General Public License along with this program.  If
   32    not, see http://www.gnu.org/licenses/.
   33 */
   34 
   35 #if HAVE_CONFIG_H
   36 # include "config.h"
   37 #endif
   38 
   39 #include "rsa-internal.h"
   40 #include "pkcs1-internal.h"
   41 #include "gmp-glue.h"
   42 
   43 int
   44 rsa_decrypt_tr(const struct rsa_public_key *pub,
   45            const struct rsa_private_key *key,
   46            void *random_ctx, nettle_random_func *random,
   47            size_t *length, uint8_t *message,
   48            const mpz_t gibberish)
   49 {
   50   TMP_GMP_DECL (m, mp_limb_t);
   51   TMP_GMP_DECL (em, uint8_t);
   52   mp_size_t key_limb_size;
   53   int res;
   54 
   55   /* First check that input is in range. */
   56   if (mpz_sgn (gibberish) < 0 || mpz_cmp (gibberish, pub->n) >= 0)
   57     return 0;
   58 
   59   key_limb_size = mpz_size(pub->n);
   60 
   61   TMP_GMP_ALLOC (m, key_limb_size);
   62   TMP_GMP_ALLOC (em, key->size);
   63   mpz_limbs_copy(m, gibberish, key_limb_size);
   64 
   65   res = _rsa_sec_compute_root_tr (pub, key, random_ctx, random, m, m);
   66 
   67   mpn_get_base256 (em, key->size, m, key_limb_size);
   68 
   69   res &= _pkcs1_sec_decrypt_variable (length, message, key->size, em);
   70 
   71   TMP_GMP_FREE (em);
   72   TMP_GMP_FREE (m);
   73   return res;
   74 }