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/* LibTomCrypt, modular cryptographic library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
#include "tomcrypt_private.h"
/**
@file der_decode_asn1_identifier.c
ASN.1 DER, decode the ASN.1 Identifier, Steffen Jaeckel
*/
#ifdef LTC_DER
/* c.f. X.680 & X.690, some decisions backed by X.690 ch. 10.2 */
static const unsigned char tag_constructed_map[] =
{
/* 0 */
255,
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
/* 5 */
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
/* 10 */
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
/* 15 */
255,
LTC_ASN1_PC_CONSTRUCTED,
LTC_ASN1_PC_CONSTRUCTED,
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
/* 20 */
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
/* 25 */
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
LTC_ASN1_PC_PRIMITIVE,
};
static const unsigned long tag_constructed_map_sz = sizeof(tag_constructed_map)/sizeof(tag_constructed_map[0]);
/**
Decode the ASN.1 Identifier
@param id Where to store the decoded Identifier
@param in Where to read the Identifier from
@param inlen [in/out] The size of in available/read
@return CRYPT_OK if successful
*/
int der_decode_asn1_identifier(const unsigned char *in, unsigned long *inlen, ltc_asn1_list *id)
{
ulong64 tmp;
unsigned long tag_len;
int err;
LTC_ARGCHK(id != NULL);
LTC_ARGCHK(in != NULL);
LTC_ARGCHK(inlen != NULL);
if (*inlen == 0) {
return CRYPT_BUFFER_OVERFLOW;
}
tag_len = 1;
id->klass = (in[0] >> 6) & 0x3;
id->pc = (in[0] >> 5) & 0x1;
id->tag = in[0] & 0x1f;
err = CRYPT_OK;
if (id->tag == 0x1f) {
id->tag = 0;
do {
if (*inlen < tag_len) {
/* break the loop and trigger the BOF error-code */
tmp = 0xff;
break;
}
id->tag <<= 7;
id->tag |= in[tag_len] & 0x7f;
tmp = in[tag_len] & 0x80;
tag_len++;
} while ((tmp != 0) && (tag_len < 10));
if (tmp != 0) {
err = CRYPT_BUFFER_OVERFLOW;
} else if (id->tag < 0x1f) {
err = CRYPT_PK_ASN1_ERROR;
}
}
if (err != CRYPT_OK) {
id->pc = 0;
id->klass = 0;
id->tag = 0;
} else {
*inlen = tag_len;
if ((id->klass == LTC_ASN1_CL_UNIVERSAL) &&
(id->tag < der_asn1_tag_to_type_map_sz) &&
(id->tag < tag_constructed_map_sz) &&
(id->pc == tag_constructed_map[id->tag])) {
id->type = der_asn1_tag_to_type_map[id->tag];
} else {
if ((id->klass == LTC_ASN1_CL_UNIVERSAL) && (id->tag == 0)) {
id->type = LTC_ASN1_EOL;
} else {
id->type = LTC_ASN1_CUSTOM_TYPE;
}
}
}
return CRYPT_OK;
}
#endif
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