2 * Copyright 2020 The OpenSSL Project Authors. All Rights Reserved.
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
12 #include "internal/cryptlib.h"
13 #include "internal/der.h"
14 #include "crypto/bn.h"
16 static int int_start_context(WPACKET *pkt, int tag)
20 if (!ossl_assert(tag <= 30))
22 return WPACKET_start_sub_packet(pkt);
25 static int int_end_context(WPACKET *pkt, int tag)
28 * If someone set the flag WPACKET_FLAGS_ABANDON_ON_ZERO_LENGTH on this
29 * sub-packet and this sub-packet has nothing written to it, the DER length
30 * will not be written, and the total written size will be unchanged before
31 * and after WPACKET_close(). We use size1 and size2 to determine if
32 * anything was written, and only write our tag if it has.
39 if (!ossl_assert(tag <= 30))
42 /* Context specific are normally (?) constructed */
43 tag |= DER_F_CONSTRUCTED | DER_C_CONTEXT;
45 return WPACKET_get_total_written(pkt, &size1)
47 && WPACKET_get_total_written(pkt, &size2)
48 && (size1 == size2 || WPACKET_put_bytes_u8(pkt, tag));
51 int ossl_DER_w_precompiled(WPACKET *pkt, int tag,
52 const unsigned char *precompiled,
55 return int_start_context(pkt, tag)
56 && WPACKET_memcpy(pkt, precompiled, precompiled_n)
57 && int_end_context(pkt, tag);
60 int ossl_DER_w_boolean(WPACKET *pkt, int tag, int b)
62 return int_start_context(pkt, tag)
63 && WPACKET_start_sub_packet(pkt)
64 && (!b || WPACKET_put_bytes_u8(pkt, 0xFF))
65 && !WPACKET_close(pkt)
66 && !WPACKET_put_bytes_u8(pkt, DER_P_BOOLEAN)
67 && int_end_context(pkt, tag);
70 int ossl_DER_w_octet_string(WPACKET *pkt, int tag,
71 const unsigned char *data, size_t data_n)
73 return int_start_context(pkt, tag)
74 && WPACKET_start_sub_packet(pkt)
75 && WPACKET_memcpy(pkt, data, data_n)
77 && WPACKET_put_bytes_u8(pkt, DER_P_OCTET_STRING)
78 && int_end_context(pkt, tag);
81 int ossl_DER_w_octet_string_uint32(WPACKET *pkt, int tag, uint32_t value)
83 unsigned char tmp[4] = { 0, 0, 0, 0 };
84 unsigned char *pbuf = tmp + (sizeof(tmp) - 1);
87 *pbuf-- = (value & 0xFF);
90 return ossl_DER_w_octet_string(pkt, tag, tmp, sizeof(tmp));
93 static int int_der_w_integer(WPACKET *pkt, int tag,
94 int (*put_bytes)(WPACKET *pkt, const void *v,
95 unsigned int *top_byte),
98 unsigned int top_byte = 0;
100 return int_start_context(pkt, tag)
101 && WPACKET_start_sub_packet(pkt)
102 && put_bytes(pkt, v, &top_byte)
103 && ((top_byte & 0x80) == 0 || WPACKET_put_bytes_u8(pkt, 0))
104 && WPACKET_close(pkt)
105 && WPACKET_put_bytes_u8(pkt, DER_P_INTEGER)
106 && int_end_context(pkt, tag);
109 static int int_put_bytes_uint32(WPACKET *pkt, const void *v,
110 unsigned int *top_byte)
112 const uint32_t *value = v;
113 uint32_t tmp = *value;
118 *top_byte = (tmp & 0xFF);
124 return WPACKET_put_bytes__(pkt, *value, n);
127 /* For integers, we only support unsigned values for now */
128 int ossl_DER_w_uint32(WPACKET *pkt, int tag, uint32_t v)
130 return int_der_w_integer(pkt, tag, int_put_bytes_uint32, &v);
133 static int int_put_bytes_bn(WPACKET *pkt, const void *v,
134 unsigned int *top_byte)
136 unsigned char *p = NULL;
137 size_t n = BN_num_bytes(v);
139 /* The BIGNUM limbs are in LE order */
141 ((bn_get_words(v) [(n - 1) / BN_BYTES]) >> (8 * ((n - 1) % BN_BYTES)))
144 if (!WPACKET_allocate_bytes(pkt, n, &p))
151 int ossl_DER_w_bn(WPACKET *pkt, int tag, const BIGNUM *v)
153 if (v == NULL || BN_is_negative(v))
156 return ossl_DER_w_uint32(pkt, tag, 0);
158 return int_der_w_integer(pkt, tag, int_put_bytes_bn, v);
161 int ossl_DER_w_null(WPACKET *pkt, int tag)
163 return int_start_context(pkt, tag)
164 && WPACKET_start_sub_packet(pkt)
165 && WPACKET_close(pkt)
166 && WPACKET_put_bytes_u8(pkt, DER_P_NULL)
167 && int_end_context(pkt, tag);
170 /* Constructed things need a start and an end */
171 int ossl_DER_w_begin_sequence(WPACKET *pkt, int tag)
173 return int_start_context(pkt, tag)
174 && WPACKET_start_sub_packet(pkt);
177 int ossl_DER_w_end_sequence(WPACKET *pkt, int tag)
180 * If someone set the flag WPACKET_FLAGS_ABANDON_ON_ZERO_LENGTH on this
181 * sub-packet and this sub-packet has nothing written to it, the DER length
182 * will not be written, and the total written size will be unchanged before
183 * and after WPACKET_close(). We use size1 and size2 to determine if
184 * anything was written, and only write our tag if it has.
186 * Because we know that int_end_context() needs to do the same check,
187 * we reproduce this flag if the written length was unchanged, or we will
188 * have an erroneous context tag.
192 return WPACKET_get_total_written(pkt, &size1)
193 && WPACKET_close(pkt)
194 && WPACKET_get_total_written(pkt, &size2)
196 ? WPACKET_set_flags(pkt, WPACKET_FLAGS_ABANDON_ON_ZERO_LENGTH)
197 : WPACKET_put_bytes_u8(pkt, DER_F_CONSTRUCTED | DER_P_SEQUENCE))
198 && int_end_context(pkt, tag);