crypto/rsa/rsa_x931.c

   1 /*
   2  * Copyright 2005-2017 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <stdio.h>
  11 #include "internal/cryptlib.h"
  12 #include <openssl/bn.h>
  13 #include <openssl/rsa.h>
  14 #include <openssl/objects.h>
  15
  16 int RSA_padding_add_X931(unsigned char *to, int tlen,
  17                          const unsigned char *from, int flen)
  18 {
  19     int j;
  20     unsigned char *p;
  21
  22     /*
  23      * Absolute minimum amount of padding is 1 header nibble, 1 padding
  24      * nibble and 2 trailer bytes: but 1 hash if is already in 'from'.
  25      */
  26
  27     j = tlen - flen - 2;
  28
  29     if (j < 0) {
  30         RSAerr(RSA_F_RSA_PADDING_ADD_X931, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
  31         return -1;
  32     }
  33
  34     p = (unsigned char *)to;
  35
  36     /* If no padding start and end nibbles are in one byte */
  37     if (j == 0) {
  38         *p++ = 0x6A;
  39     } else {
  40         *p++ = 0x6B;
  41         if (j > 1) {
  42             memset(p, 0xBB, j - 1);
  43             p += j - 1;
  44         }
  45         *p++ = 0xBA;
  46     }
  47     memcpy(p, from, (unsigned int)flen);
  48     p += flen;
  49     *p = 0xCC;
  50     return 1;
  51 }
  52
  53 int RSA_padding_check_X931(unsigned char *to, int tlen,
  54                            const unsigned char *from, int flen, int num)
  55 {
  56     int i = 0, j;
  57     const unsigned char *p;
  58
  59     p = from;
  60     if ((num != flen) || ((*p != 0x6A) && (*p != 0x6B))) {
  61         RSAerr(RSA_F_RSA_PADDING_CHECK_X931, RSA_R_INVALID_HEADER);
  62         return -1;
  63     }
  64
  65     if (*p++ == 0x6B) {
  66         j = flen - 3;
  67         for (i = 0; i < j; i++) {
  68             unsigned char c = *p++;
  69             if (c == 0xBA)
  70                 break;
  71             if (c != 0xBB) {
  72                 RSAerr(RSA_F_RSA_PADDING_CHECK_X931, RSA_R_INVALID_PADDING);
  73                 return -1;
  74             }
  75         }
  76
  77         j -= i;
  78
  79         if (i == 0) {
  80             RSAerr(RSA_F_RSA_PADDING_CHECK_X931, RSA_R_INVALID_PADDING);
  81             return -1;
  82         }
  83
  84     } else {
  85         j = flen - 2;
  86     }
  87
  88     if (p[j] != 0xCC) {
  89         RSAerr(RSA_F_RSA_PADDING_CHECK_X931, RSA_R_INVALID_TRAILER);
  90         return -1;
  91     }
  92
  93     memcpy(to, p, (unsigned int)j);
  94
  95     return j;
  96 }
  97
  98 /* Translate between X931 hash ids and NIDs */
  99
 100 int RSA_X931_hash_id(int nid)
 101 {
 102     switch (nid) {
 103     case NID_sha1:
 104         return 0x33;
 105
 106     case NID_sha256:
 107         return 0x34;
 108
 109     case NID_sha384:
 110         return 0x36;
 111
 112     case NID_sha512:
 113         return 0x35;
 114
 115     }
 116     return -1;
 117 }