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))
41 return WPACKET_get_total_written(pkt, &size1)
43 && WPACKET_get_total_written(pkt, &size2)
44 && (size1 == size2 || WPACKET_put_bytes_u8(pkt, DER_C_CONTEXT | tag));
47 int DER_w_precompiled(WPACKET *pkt, int tag,
48 const unsigned char *precompiled, size_t precompiled_n)
50 return int_start_context(pkt, tag)
51 && WPACKET_memcpy(pkt, precompiled, precompiled_n)
52 && int_end_context(pkt, tag);
55 int DER_w_boolean(WPACKET *pkt, int tag, int b)
57 return int_start_context(pkt, tag)
58 && WPACKET_start_sub_packet(pkt)
59 && (!b || WPACKET_put_bytes_u8(pkt, 0xFF))
60 && !WPACKET_close(pkt)
61 && !WPACKET_put_bytes_u8(pkt, DER_P_BOOLEAN)
62 && int_end_context(pkt, tag);
65 static int int_der_w_integer(WPACKET *pkt, int tag,
66 int (*put_bytes)(WPACKET *pkt, const void *v,
67 unsigned int *top_byte),
70 unsigned int top_byte = 0;
72 return int_start_context(pkt, tag)
73 && WPACKET_start_sub_packet(pkt)
74 && put_bytes(pkt, v, &top_byte)
75 && ((top_byte & 0x80) == 0 || WPACKET_put_bytes_u8(pkt, 0))
77 && WPACKET_put_bytes_u8(pkt, DER_P_INTEGER)
78 && int_end_context(pkt, tag);
81 static int int_put_bytes_ulong(WPACKET *pkt, const void *v,
82 unsigned int *top_byte)
84 const unsigned long *value = v;
85 unsigned long tmp = *value;
90 *top_byte = (tmp & 0xFF);
96 return WPACKET_put_bytes__(pkt, *value, n);
99 /* For integers, we only support unsigned values for now */
100 int DER_w_ulong(WPACKET *pkt, int tag, unsigned long v)
102 return int_der_w_integer(pkt, tag, int_put_bytes_ulong, &v);
105 static int int_put_bytes_bn(WPACKET *pkt, const void *v,
106 unsigned int *top_byte)
108 unsigned char *p = NULL;
109 size_t n = BN_num_bytes(v);
111 /* The BIGNUM limbs are in LE order */
113 ((bn_get_words(v) [(n - 1) / BN_BYTES]) >> (8 * ((n - 1) % BN_BYTES)))
116 if (!WPACKET_allocate_bytes(pkt, n, &p))
123 int DER_w_bn(WPACKET *pkt, int tag, const BIGNUM *v)
125 if (v == NULL || BN_is_negative(v))
128 return DER_w_ulong(pkt, tag, 0);
130 return int_der_w_integer(pkt, tag, int_put_bytes_bn, v);
133 int DER_w_null(WPACKET *pkt, int tag)
135 return int_start_context(pkt, tag)
136 && WPACKET_start_sub_packet(pkt)
137 && WPACKET_close(pkt)
138 && WPACKET_put_bytes_u8(pkt, DER_P_NULL)
139 && int_end_context(pkt, tag);
142 /* Constructed things need a start and an end */
143 int DER_w_begin_sequence(WPACKET *pkt, int tag)
145 return int_start_context(pkt, tag)
146 && WPACKET_start_sub_packet(pkt);
149 int DER_w_end_sequence(WPACKET *pkt, int tag)
152 * If someone set the flag WPACKET_FLAGS_ABANDON_ON_ZERO_LENGTH on this
153 * sub-packet and this sub-packet has nothing written to it, the DER length
154 * will not be written, and the total written size will be unchanged before
155 * and after WPACKET_close(). We use size1 and size2 to determine if
156 * anything was written, and only write our tag if it has.
158 * Because we know that int_end_context() needs to do the same check,
159 * we reproduce this flag if the written length was unchanged, or we will
160 * have an erroneous context tag.
164 return WPACKET_get_total_written(pkt, &size1)
165 && WPACKET_close(pkt)
166 && WPACKET_get_total_written(pkt, &size2)
168 ? WPACKET_set_flags(pkt, WPACKET_FLAGS_ABANDON_ON_ZERO_LENGTH)
169 : WPACKET_put_bytes_u8(pkt, DER_F_CONSTRUCTED | DER_P_SEQUENCE))
170 && int_end_context(pkt, tag);