File syn_asn1.h¶

FileList > crypto > syn_asn1.h

Zero-Heap ASN.1 DER (Distinguished Encoding Rules) TLV Parser.

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

Classes¶

Type	Name
struct	SYN_ASN1_Element Parsed ASN.1 TLV element header.

Public Functions¶

Type	Name
bool	syn_asn1_enter_container (const SYN_ASN1_Element * container, const uint8_t ** child_buf, size_t * child_len) Unwraps a constructed container (SEQUENCE, SET, or context-specific tag) for child iteration.
bool	syn_asn1_get_bit_string (const SYN_ASN1_Element * elem, const uint8_t ** bits_out, size_t * bit_len_out) Extract Bit String payload (stripping unused bits count prefix byte).
bool	syn_asn1_get_integer (const SYN_ASN1_Element * elem, const uint8_t ** int_out, size_t * int_len_out) Extract raw integer bytes (stripping leading sign zero padding if present).
bool	syn_asn1_match_oid (const SYN_ASN1_Element * elem, const uint8_t * expected_oid, size_t oid_len) Compare ASN.1 Object Identifier (OID) against expected byte array.
bool	syn_asn1_parse_element (const uint8_t * buf, size_t len, SYN_ASN1_Element * elem_out) Parse a single ASN.1 DER TLV element from buffer.
bool	syn_asn1_step (const uint8_t ** buf, size_t * len, SYN_ASN1_Element * elem_out) Skip/advance past current TLV element in a DER buffer.

Macros¶

Type	Name
define	SYN_ASN1_CLASS_APPLICATION `0x40U` APPLICATION tag class (0x40).
define	SYN_ASN1_CLASS_CONTEXT_SPECIFIC `0x80U` CONTEXT-SPECIFIC tag class (0x80).
define	SYN_ASN1_CLASS_MASK `0xC0U` ASN.1 Tag Class / Form Masking.
define	SYN_ASN1_CLASS_PRIVATE `0xC0U` PRIVATE tag class (0xC0).
define	SYN_ASN1_CLASS_UNIVERSAL `0x00U` UNIVERSAL tag class (0x00).
define	SYN_ASN1_CONSTRUCTED_MASK `0x20U` Mask for ASN.1 constructed form (bit 5).
define	SYN_ASN1_TAG_BIT_STRING `0x03U` ASN.1 BIT STRING universal tag.
define	SYN_ASN1_TAG_BOOLEAN `0x01U` ASN.1 Universal Tag Constants.
define	SYN_ASN1_TAG_GENERALIZEDTIME `0x18U` ASN.1 GeneralizedTime universal tag.
define	SYN_ASN1_TAG_INTEGER `0x02U` ASN.1 INTEGER universal tag.
define	SYN_ASN1_TAG_NULL `0x05U` ASN.1 NULL universal tag.
define	SYN_ASN1_TAG_NUM_MASK `0x1FU` Mask for ASN.1 tag number (lower 5 bits).
define	SYN_ASN1_TAG_OCTET_STRING `0x04U` ASN.1 OCTET STRING universal tag.
define	SYN_ASN1_TAG_OID `0x06U` ASN.1 OID universal tag.
define	SYN_ASN1_TAG_SEQUENCE `0x30U` ASN.1 SEQUENCE universal tag.
define	SYN_ASN1_TAG_SET `0x31U` ASN.1 SET universal tag.
define	SYN_ASN1_TAG_UTCTIME `0x17U` ASN.1 UTCTime universal tag.

Public Functions Documentation¶

function syn_asn1_enter_container¶

Unwraps a constructed container (SEQUENCE, SET, or context-specific tag) for child iteration.

bool syn_asn1_enter_container (
    const SYN_ASN1_Element * container,
    const uint8_t ** child_buf,
    size_t * child_len
)

Parameters:

container Pointer to container TLV element header.
child_buf [out] Sub-slice buffer pointer to container payload.
child_len [out] Length of container payload.

Returns:

true if element is constructed and valid payload extracted.

function syn_asn1_get_bit_string¶

Extract Bit String payload (stripping unused bits count prefix byte).

bool syn_asn1_get_bit_string (
    const SYN_ASN1_Element * elem,
    const uint8_t ** bits_out,
    size_t * bit_len_out
)

Parameters:

elem Parsed ASN.1 BIT STRING element.
bits_out [out] Pointer to raw bit string bytes.
bit_len_out [out] Number of valid bits in payload.

Returns:

true on success.

function syn_asn1_get_integer¶

Extract raw integer bytes (stripping leading sign zero padding if present).

bool syn_asn1_get_integer (
    const SYN_ASN1_Element * elem,
    const uint8_t ** int_out,
    size_t * int_len_out
)

Parameters:

elem Parsed ASN.1 INTEGER element.
int_out [out] Pointer to integer payload bytes.
int_len_out [out] Length of integer payload bytes.

Returns:

true on success.

function syn_asn1_match_oid¶

Compare ASN.1 Object Identifier (OID) against expected byte array.

bool syn_asn1_match_oid (
    const SYN_ASN1_Element * elem,
    const uint8_t * expected_oid,
    size_t oid_len
)

Parameters:

elem Parsed ASN.1 OID element.
expected_oid Expected encoded OID payload bytes.
oid_len Length of expected OID payload bytes.

Returns:

true if OIDs match.

function syn_asn1_parse_element¶

Parse a single ASN.1 DER TLV element from buffer.

bool syn_asn1_parse_element (
    const uint8_t * buf,
    size_t len,
    SYN_ASN1_Element * elem_out
)

Parameters:

buf Data buffer.
len Length of available bytes in buffer.
elem_out [out] Output parsed element.

Returns:

true if valid TLV element parsed, false on truncation or encoding error.

function syn_asn1_step¶

Skip/advance past current TLV element in a DER buffer.

bool syn_asn1_step (
    const uint8_t ** buf,
    size_t * len,
    SYN_ASN1_Element * elem_out
)

Parameters:

buf Pointer to buffer pointer (updated on success).
len Pointer to available length (updated on success).
elem_out [out] Optional parsed element header.

Returns:

true on success.

Macro Definition Documentation¶

define SYN_ASN1_CLASS_APPLICATION¶

APPLICATION tag class (0x40).

#define SYN_ASN1_CLASS_APPLICATION `0x40U`

define SYN_ASN1_CLASS_CONTEXT_SPECIFIC¶

CONTEXT-SPECIFIC tag class (0x80).

#define SYN_ASN1_CLASS_CONTEXT_SPECIFIC `0x80U`

define SYN_ASN1_CLASS_MASK¶

ASN.1 Tag Class / Form Masking.

#define SYN_ASN1_CLASS_MASK `0xC0U`

Mask for ASN.1 tag class (top 2 bits).

define SYN_ASN1_CLASS_PRIVATE¶

PRIVATE tag class (0xC0).

#define SYN_ASN1_CLASS_PRIVATE `0xC0U`

define SYN_ASN1_CLASS_UNIVERSAL¶

UNIVERSAL tag class (0x00).

#define SYN_ASN1_CLASS_UNIVERSAL `0x00U`

define SYN_ASN1_CONSTRUCTED_MASK¶

Mask for ASN.1 constructed form (bit 5).

#define SYN_ASN1_CONSTRUCTED_MASK `0x20U`

define SYN_ASN1_TAG_BIT_STRING¶

ASN.1 BIT STRING universal tag.

#define SYN_ASN1_TAG_BIT_STRING `0x03U`

define SYN_ASN1_TAG_BOOLEAN¶

ASN.1 Universal Tag Constants.

#define SYN_ASN1_TAG_BOOLEAN `0x01U`

ASN.1 BOOLEAN universal tag.

define SYN_ASN1_TAG_GENERALIZEDTIME¶

ASN.1 GeneralizedTime universal tag.

#define SYN_ASN1_TAG_GENERALIZEDTIME `0x18U`

define SYN_ASN1_TAG_INTEGER¶

ASN.1 INTEGER universal tag.

#define SYN_ASN1_TAG_INTEGER `0x02U`

define SYN_ASN1_TAG_NULL¶

ASN.1 NULL universal tag.

#define SYN_ASN1_TAG_NULL `0x05U`

define SYN_ASN1_TAG_NUM_MASK¶

Mask for ASN.1 tag number (lower 5 bits).

#define SYN_ASN1_TAG_NUM_MASK `0x1FU`

define SYN_ASN1_TAG_OCTET_STRING¶

ASN.1 OCTET STRING universal tag.

#define SYN_ASN1_TAG_OCTET_STRING `0x04U`

define SYN_ASN1_TAG_OID¶

ASN.1 OID universal tag.

#define SYN_ASN1_TAG_OID `0x06U`

define SYN_ASN1_TAG_SEQUENCE¶

ASN.1 SEQUENCE universal tag.

#define SYN_ASN1_TAG_SEQUENCE `0x30U`

define SYN_ASN1_TAG_SET¶

ASN.1 SET universal tag.

#define SYN_ASN1_TAG_SET `0x31U`

define SYN_ASN1_TAG_UTCTIME¶

ASN.1 UTCTime universal tag.

#define SYN_ASN1_TAG_UTCTIME `0x17U`

The documentation for this class was generated from the following file src/syntropic/crypto/syn_asn1.h