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 == 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 | |
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 | |
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 | 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 | |
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 | |