File syn_asn1.c

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

• #include "syntropic/crypto/syn_asn1.h"
• #include <string.h>

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.

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.

---

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