crypto/asn1/x_bignum.c

   1 /*
   2  * Copyright 2000-2016 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 #include <stdio.h>
  11 #include "internal/cryptlib.h"
  12 #include <openssl/asn1t.h>
  13 #include <openssl/bn.h>
  14
  15 /*
  16  * Custom primitive type for BIGNUM handling. This reads in an ASN1_INTEGER
  17  * as a BIGNUM directly. Currently it ignores the sign which isn't a problem
  18  * since all BIGNUMs used are non negative and anything that looks negative
  19  * is normally due to an encoding error.
  20  */
  21
  22 #define BN_SENSITIVE    1
  23
  24 static int bn_new(ASN1_VALUE **pval, const ASN1_ITEM *it);
  25 static int bn_secure_new(ASN1_VALUE **pval, const ASN1_ITEM *it);
  26 static void bn_free(ASN1_VALUE **pval, const ASN1_ITEM *it);
  27
  28 static int bn_i2c(const ASN1_VALUE **pval, unsigned char *cont, int *putype,
  29                   const ASN1_ITEM *it);
  30 static int bn_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
  31                   int utype, char *free_cont, const ASN1_ITEM *it);
  32 static int bn_secure_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
  33                          int utype, char *free_cont, const ASN1_ITEM *it);
  34 static int bn_print(BIO *out, const ASN1_VALUE **pval, const ASN1_ITEM *it,
  35                     int indent, const ASN1_PCTX *pctx);
  36
  37 static ASN1_PRIMITIVE_FUNCS bignum_pf = {
  38     NULL, 0,
  39     bn_new,
  40     bn_free,
  41     0,
  42     bn_c2i,
  43     bn_i2c,
  44     bn_print
  45 };
  46
  47 static ASN1_PRIMITIVE_FUNCS cbignum_pf = {
  48     NULL, 0,
  49     bn_secure_new,
  50     bn_free,
  51     0,
  52     bn_secure_c2i,
  53     bn_i2c,
  54     bn_print
  55 };
  56
  57 ASN1_ITEM_start(BIGNUM)
  58         ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &bignum_pf, 0, "BIGNUM"
  59 ASN1_ITEM_end(BIGNUM)
  60
  61 ASN1_ITEM_start(CBIGNUM)
  62         ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &cbignum_pf, BN_SENSITIVE, "CBIGNUM"
  63 ASN1_ITEM_end(CBIGNUM)
  64
  65 static int bn_new(ASN1_VALUE **pval, const ASN1_ITEM *it)
  66 {
  67     *pval = (ASN1_VALUE *)BN_new();
  68     if (*pval != NULL)
  69         return 1;
  70     else
  71         return 0;
  72 }
  73
  74 static int bn_secure_new(ASN1_VALUE **pval, const ASN1_ITEM *it)
  75 {
  76     *pval = (ASN1_VALUE *)BN_secure_new();
  77     if (*pval != NULL)
  78         return 1;
  79     else
  80         return 0;
  81 }
  82
  83 static void bn_free(ASN1_VALUE **pval, const ASN1_ITEM *it)
  84 {
  85     if (!*pval)
  86         return;
  87     if (it->size & BN_SENSITIVE)
  88         BN_clear_free((BIGNUM *)*pval);
  89     else
  90         BN_free((BIGNUM *)*pval);
  91     *pval = NULL;
  92 }
  93
  94 static int bn_i2c(const ASN1_VALUE **pval, unsigned char *cont, int *putype,
  95                   const ASN1_ITEM *it)
  96 {
  97     BIGNUM *bn;
  98     int pad;
  99     if (!*pval)
 100         return -1;
 101     bn = (BIGNUM *)*pval;
 102     /* If MSB set in an octet we need a padding byte */
 103     if (BN_num_bits(bn) & 0x7)
 104         pad = 0;
 105     else
 106         pad = 1;
 107     if (cont) {
 108         if (pad)
 109             *cont++ = 0;
 110         BN_bn2bin(bn, cont);
 111     }
 112     return pad + BN_num_bytes(bn);
 113 }
 114
 115 static int bn_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
 116                   int utype, char *free_cont, const ASN1_ITEM *it)
 117 {
 118     BIGNUM *bn;
 119
 120     if (*pval == NULL && !bn_new(pval, it))
 121         return 0;
 122     bn = (BIGNUM *)*pval;
 123     if (!BN_bin2bn(cont, len, bn)) {
 124         bn_free(pval, it);
 125         return 0;
 126     }
 127     return 1;
 128 }
 129
 130 static int bn_secure_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
 131                          int utype, char *free_cont, const ASN1_ITEM *it)
 132 {
 133     if (!*pval)
 134         bn_secure_new(pval, it);
 135     return bn_c2i(pval, cont, len, utype, free_cont, it);
 136 }
 137
 138 static int bn_print(BIO *out, const ASN1_VALUE **pval, const ASN1_ITEM *it,
 139                     int indent, const ASN1_PCTX *pctx)
 140 {
 141     if (!BN_print(out, *(BIGNUM **)pval))
 142         return 0;
 143     if (BIO_puts(out, "\n") <= 0)
 144         return 0;
 145     return 1;
 146 }