| 1 | /*
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| 2 | * Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
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| 3 | *
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| 4 | * Licensed under the OpenSSL license (the "License"). You may not use
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| 5 | * this file except in compliance with the License. You can obtain a copy
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| 6 | * in the file LICENSE in the source distribution or at
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| 7 | * https://www.openssl.org/source/license.html
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| 8 | */
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| 9 |
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| 10 | #include <stdio.h>
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| 11 | #include "internal/cryptlib.h"
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| 12 | #include <openssl/asn1t.h>
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| 13 | #include <openssl/bn.h>
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| 14 |
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| 15 | /*
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| 16 | * Custom primitive type for BIGNUM handling. This reads in an ASN1_INTEGER
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| 17 | * as a BIGNUM directly. Currently it ignores the sign which isn't a problem
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| 18 | * since all BIGNUMs used are non negative and anything that looks negative
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| 19 | * is normally due to an encoding error.
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| 20 | */
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| 21 |
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| 22 | #define BN_SENSITIVE 1
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| 23 |
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| 24 | static int bn_new(ASN1_VALUE **pval, const ASN1_ITEM *it);
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| 25 | static int bn_secure_new(ASN1_VALUE **pval, const ASN1_ITEM *it);
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| 26 | static void bn_free(ASN1_VALUE **pval, const ASN1_ITEM *it);
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| 27 |
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| 28 | static int bn_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype,
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| 29 | const ASN1_ITEM *it);
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| 30 | static int bn_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
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| 31 | int utype, char *free_cont, const ASN1_ITEM *it);
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| 32 | static int bn_secure_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
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| 33 | int utype, char *free_cont, const ASN1_ITEM *it);
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| 34 | static int bn_print(BIO *out, ASN1_VALUE **pval, const ASN1_ITEM *it,
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| 35 | int indent, const ASN1_PCTX *pctx);
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| 36 |
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| 37 | static ASN1_PRIMITIVE_FUNCS bignum_pf = {
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| 38 | NULL, 0,
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| 39 | bn_new,
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| 40 | bn_free,
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| 41 | 0,
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| 42 | bn_c2i,
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| 43 | bn_i2c,
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| 44 | bn_print
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| 45 | };
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| 46 |
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| 47 | static ASN1_PRIMITIVE_FUNCS cbignum_pf = {
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| 48 | NULL, 0,
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| 49 | bn_secure_new,
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| 50 | bn_free,
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| 51 | 0,
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| 52 | bn_secure_c2i,
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| 53 | bn_i2c,
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| 54 | bn_print
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| 55 | };
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| 56 |
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| 57 | ASN1_ITEM_start(BIGNUM)
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| 58 | ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &bignum_pf, 0, "BIGNUM"
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| 59 | ASN1_ITEM_end(BIGNUM)
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| 60 |
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| 61 | ASN1_ITEM_start(CBIGNUM)
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| 62 | ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &cbignum_pf, BN_SENSITIVE, "CBIGNUM"
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| 63 | ASN1_ITEM_end(CBIGNUM)
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| 64 |
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| 65 | static int bn_new(ASN1_VALUE **pval, const ASN1_ITEM *it)
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| 66 | {
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| 67 | *pval = (ASN1_VALUE *)BN_new();
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| 68 | if (*pval != NULL)
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| 69 | return 1;
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| 70 | else
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| 71 | return 0;
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| 72 | }
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| 73 |
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| 74 | static int bn_secure_new(ASN1_VALUE **pval, const ASN1_ITEM *it)
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| 75 | {
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| 76 | *pval = (ASN1_VALUE *)BN_secure_new();
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| 77 | if (*pval != NULL)
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| 78 | return 1;
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| 79 | else
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| 80 | return 0;
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| 81 | }
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| 82 |
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| 83 | static void bn_free(ASN1_VALUE **pval, const ASN1_ITEM *it)
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| 84 | {
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| 85 | if (*pval == NULL)
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| 86 | return;
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| 87 | if (it->size & BN_SENSITIVE)
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| 88 | BN_clear_free((BIGNUM *)*pval);
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| 89 | else
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| 90 | BN_free((BIGNUM *)*pval);
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| 91 | *pval = NULL;
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| 92 | }
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| 93 |
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| 94 | static int bn_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype,
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| 95 | const ASN1_ITEM *it)
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| 96 | {
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| 97 | BIGNUM *bn;
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| 98 | int pad;
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| 99 | if (*pval == NULL)
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| 100 | return -1;
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| 101 | bn = (BIGNUM *)*pval;
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| 102 | /* If MSB set in an octet we need a padding byte */
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| 103 | if (BN_num_bits(bn) & 0x7)
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| 104 | pad = 0;
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| 105 | else
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| 106 | pad = 1;
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| 107 | if (cont) {
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| 108 | if (pad)
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| 109 | *cont++ = 0;
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| 110 | BN_bn2bin(bn, cont);
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| 111 | }
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| 112 | return pad + BN_num_bytes(bn);
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| 113 | }
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| 114 |
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| 115 | static int bn_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
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| 116 | int utype, char *free_cont, const ASN1_ITEM *it)
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| 117 | {
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| 118 | BIGNUM *bn;
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| 119 |
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| 120 | if (*pval == NULL && !bn_new(pval, it))
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| 121 | return 0;
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| 122 | bn = (BIGNUM *)*pval;
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| 123 | if (!BN_bin2bn(cont, len, bn)) {
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| 124 | bn_free(pval, it);
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| 125 | return 0;
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| 126 | }
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| 127 | return 1;
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| 128 | }
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| 129 |
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| 130 | static int bn_secure_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
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| 131 | int utype, char *free_cont, const ASN1_ITEM *it)
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| 132 | {
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| 133 | int ret;
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| 134 | BIGNUM *bn;
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| 135 |
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| 136 | if (*pval == NULL && !bn_secure_new(pval, it))
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| 137 | return 0;
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| 138 |
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| 139 | ret = bn_c2i(pval, cont, len, utype, free_cont, it);
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| 140 | if (!ret)
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| 141 | return 0;
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| 142 |
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| 143 | /* Set constant-time flag for all secure BIGNUMS */
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| 144 | bn = (BIGNUM *)*pval;
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| 145 | BN_set_flags(bn, BN_FLG_CONSTTIME);
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| 146 | return ret;
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| 147 | }
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| 148 |
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| 149 | static int bn_print(BIO *out, ASN1_VALUE **pval, const ASN1_ITEM *it,
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| 150 | int indent, const ASN1_PCTX *pctx)
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| 151 | {
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| 152 | if (!BN_print(out, *(BIGNUM **)pval))
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| 153 | return 0;
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| 154 | if (BIO_puts(out, "\n") <= 0)
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| 155 | return 0;
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| 156 | return 1;
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| 157 | }
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