release/src/router/nettle/pkcs1-rsa-sha256.c

   1 /* pkcs1-rsa-sha256.c
   2  *
   3  * PKCS stuff for rsa-sha256.
   4  */
   5
   6 /* nettle, low-level cryptographics library
   7  *
   8  * Copyright (C) 2001, 2003, 2006 Niels Möller
   9  *
  10  * The nettle library is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU Lesser General Public License as published by
  12  * the Free Software Foundation; either version 2.1 of the License, or (at your
  13  * option) any later version.
  14  *
  15  * The nettle library is distributed in the hope that it will be useful, but
  16  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  17  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  18  * License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public License
  21  * along with the nettle library; see the file COPYING.LIB.  If not, write to
  22  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  23  * MA 02111-1301, USA.
  24  */
  25
  26 #if HAVE_CONFIG_H
  27 # include "config.h"
  28 #endif
  29
  30 #include <assert.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33
  34 #include "rsa.h"
  35
  36 #include "bignum.h"
  37 #include "pkcs1.h"
  38
  39 #include "nettle-internal.h"
  40
  41 /* From RFC 3447, Public-Key Cryptography Standards (PKCS) #1: RSA
  42  * Cryptography Specifications Version 2.1.
  43  *
  44  *     id-sha256    OBJECT IDENTIFIER ::=
  45  *       {joint-iso-itu-t(2) country(16) us(840) organization(1)
  46  *         gov(101) csor(3) nistalgorithm(4) hashalgs(2) 1}
  47  */
  48
  49 static const uint8_t
  50 sha256_prefix[] =
  51 {
  52   /* 19 octets prefix, 32 octets hash, total 51 */
  53   0x30,      49, /* SEQUENCE */
  54     0x30,    13, /* SEQUENCE */
  55       0x06,   9, /* OBJECT IDENTIFIER */
  56         0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
  57       0x05,   0, /* NULL */
  58     0x04,    32  /* OCTET STRING */
  59       /* Here comes the raw hash value */
  60 };
  61
  62 int
  63 pkcs1_rsa_sha256_encode(mpz_t m, unsigned key_size, struct sha256_ctx *hash)
  64 {
  65   uint8_t *p;
  66   TMP_DECL(em, uint8_t, NETTLE_MAX_BIGNUM_SIZE);
  67   TMP_ALLOC(em, key_size);
  68
  69   p = _pkcs1_signature_prefix(key_size, em,
  70                               sizeof(sha256_prefix),
  71                               sha256_prefix,
  72                               SHA256_DIGEST_SIZE);
  73   if (p)
  74     {
  75       sha256_digest(hash, SHA256_DIGEST_SIZE, p);
  76       nettle_mpz_set_str_256_u(m, key_size, em);
  77       return 1;
  78     }
  79   else
  80     return 0;
  81 }
  82
  83 int
  84 pkcs1_rsa_sha256_encode_digest(mpz_t m, unsigned key_size, const uint8_t *digest)
  85 {
  86   uint8_t *p;
  87   TMP_DECL(em, uint8_t, NETTLE_MAX_BIGNUM_SIZE);
  88   TMP_ALLOC(em, key_size);
  89
  90   p = _pkcs1_signature_prefix(key_size, em,
  91                               sizeof(sha256_prefix),
  92                               sha256_prefix,
  93                               SHA256_DIGEST_SIZE);
  94   if (p)
  95     {
  96       memcpy(p, digest, SHA256_DIGEST_SIZE);
  97       nettle_mpz_set_str_256_u(m, key_size, em);
  98       return 1;
  99     }
 100   else
 101     return 0;
 102 }