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
ASN1_ITEM_start(BIGNUM)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
bn_secure_new(ASN1_VALUE ** pval,const ASN1_ITEM * it)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
bn_free(ASN1_VALUE ** pval,const ASN1_ITEM * it)83 static void bn_free(ASN1_VALUE **pval, const ASN1_ITEM *it)
84 {
85 if (*pval == NULL)
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
bn_i2c(const ASN1_VALUE ** pval,unsigned char * cont,int * putype,const ASN1_ITEM * it)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 == NULL)
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
bn_c2i(ASN1_VALUE ** pval,const unsigned char * cont,int len,int utype,char * free_cont,const ASN1_ITEM * it)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
bn_secure_c2i(ASN1_VALUE ** pval,const unsigned char * cont,int len,int utype,char * free_cont,const ASN1_ITEM * it)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 int ret;
134 BIGNUM *bn;
135
136 if (*pval == NULL && !bn_secure_new(pval, it))
137 return 0;
138
139 ret = bn_c2i(pval, cont, len, utype, free_cont, it);
140 if (!ret)
141 return 0;
142
143 /* Set constant-time flag for all secure BIGNUMS */
144 bn = (BIGNUM *)*pval;
145 BN_set_flags(bn, BN_FLG_CONSTTIME);
146 return ret;
147 }
148
bn_print(BIO * out,const ASN1_VALUE ** pval,const ASN1_ITEM * it,int indent,const ASN1_PCTX * pctx)149 static int bn_print(BIO *out, const ASN1_VALUE **pval, const ASN1_ITEM *it,
150 int indent, const ASN1_PCTX *pctx)
151 {
152 if (!BN_print(out, *(BIGNUM **)pval))
153 return 0;
154 if (BIO_puts(out, "\n") <= 0)
155 return 0;
156 return 1;
157 }
158
