crypto/rsa/rsa_x931.c

   1 /*
   2  * Copyright 2005-2020 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (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 /*
  11  * RSA low level APIs are deprecated for public use, but still ok for
  12  * internal use.
  13  */
  14 #include "internal/deprecated.h"
  15
  16 #include <stdio.h>
  17 #include "internal/cryptlib.h"
  18 #include <openssl/bn.h>
  19 #include <openssl/rsa.h>
  20 #include <openssl/objects.h>
  21
  22 int RSA_padding_add_X931(unsigned char *to, int tlen,
  23                          const unsigned char *from, int flen)
  24 {
  25     int j;
  26     unsigned char *p;
  27
  28     /*
  29      * Absolute minimum amount of padding is 1 header nibble, 1 padding
  30      * nibble and 2 trailer bytes: but 1 hash if is already in 'from'.
  31      */
  32
  33     j = tlen - flen - 2;
  34
  35     if (j < 0) {
  36         RSAerr(RSA_F_RSA_PADDING_ADD_X931, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
  37         return -1;
  38     }
  39
  40     p = (unsigned char *)to;
  41
  42     /* If no padding start and end nibbles are in one byte */
  43     if (j == 0) {
  44         *p++ = 0x6A;
  45     } else {
  46         *p++ = 0x6B;
  47         if (j > 1) {
  48             memset(p, 0xBB, j - 1);
  49             p += j - 1;
  50         }
  51         *p++ = 0xBA;
  52     }
  53     memcpy(p, from, (unsigned int)flen);
  54     p += flen;
  55     *p = 0xCC;
  56     return 1;
  57 }
  58
  59 int RSA_padding_check_X931(unsigned char *to, int tlen,
  60                            const unsigned char *from, int flen, int num)
  61 {
  62     int i = 0, j;
  63     const unsigned char *p;
  64
  65     p = from;
  66     if ((num != flen) || ((*p != 0x6A) && (*p != 0x6B))) {
  67         RSAerr(RSA_F_RSA_PADDING_CHECK_X931, RSA_R_INVALID_HEADER);
  68         return -1;
  69     }
  70
  71     if (*p++ == 0x6B) {
  72         j = flen - 3;
  73         for (i = 0; i < j; i++) {
  74             unsigned char c = *p++;
  75             if (c == 0xBA)
  76                 break;
  77             if (c != 0xBB) {
  78                 RSAerr(RSA_F_RSA_PADDING_CHECK_X931, RSA_R_INVALID_PADDING);
  79                 return -1;
  80             }
  81         }
  82
  83         j -= i;
  84
  85         if (i == 0) {
  86             RSAerr(RSA_F_RSA_PADDING_CHECK_X931, RSA_R_INVALID_PADDING);
  87             return -1;
  88         }
  89
  90     } else {
  91         j = flen - 2;
  92     }
  93
  94     if (p[j] != 0xCC) {
  95         RSAerr(RSA_F_RSA_PADDING_CHECK_X931, RSA_R_INVALID_TRAILER);
  96         return -1;
  97     }
  98
  99     memcpy(to, p, (unsigned int)j);
 100
 101     return j;
 102 }
 103
 104 /* Translate between X931 hash ids and NIDs */
 105
 106 int RSA_X931_hash_id(int nid)
 107 {
 108     switch (nid) {
 109     case NID_sha1:
 110         return 0x33;
 111
 112     case NID_sha256:
 113         return 0x34;
 114
 115     case NID_sha384:
 116         return 0x36;
 117
 118     case NID_sha512:
 119         return 0x35;
 120
 121     }
 122     return -1;
 123 }