tlv.py

from typing import Union
from enum import IntEnum


class FieldTag(IntEnum):
    STRUCT_TYPE = 0x01
    STRUCT_VERSION = 0x02
    CONTACT_NAME = 0xf0
    SCOPE = 0xf1
    PREVIOUS_CONTACT_NAME = 0xf3
    ACCOUNT_IDENTIFIER = 0xf2
    PREVIOUS_IDENTIFIER = 0xf4
    PREVIOUS_SCOPE = 0xf5
    GROUP_HANDLE = 0xf6
    CHALLENGE = 0x12
    DER_SIGNATURE = 0x15
    DERIVATION_PATH = 0x21
    ADDRESS = 0x22
    CHAIN_ID = 0x23
    TICKER = 0x24
    TX_HASH = 0x27
    DOMAIN_HASH = 0x28
    SELECTOR = 0x40
    BLOCKCHAIN_FAMILY = 0x51
    NETWORK_NAME = 0x52
    NETWORK_ICON_HASH = 0x53
    HMAC_PROOF = 0x29
    HMAC_REST = 0xf7
    TX_CHECKS_NORMALIZED_RISK = 0x80
    TX_CHECKS_NORMALIZED_CATEGORY = 0x81
    MESSAGE = 0x82
    TINY_URL = 0x83
    TX_TYPE = 0x84
    THRESHOLD = 0xa0,
    SIGNERS_COUNT = 0xa1,
    LESM_ROLE = 0xa2,


class TlvSerializable:
    def serialize(self) -> bytes:
        raise NotImplementedError

    @staticmethod
    def der_encode(value: int) -> bytes:
        # max() to have minimum length of 1
        value_bytes = value.to_bytes(max(1, (value.bit_length() + 7) // 8), 'big')
        if value >= 0x80:
            value_bytes = (0x80 | len(value_bytes)).to_bytes(1, 'big') + value_bytes
        return value_bytes

    @staticmethod
    def serialize_field(tag: int, value: Union[int, str, bytes, bytearray]) -> bytes:
        if isinstance(value, int):
            # max() to have minimum length of 1
            value = value.to_bytes(max(1, (value.bit_length() + 7) // 8), 'big')
        elif isinstance(value, str):
            value = value.encode()
        elif isinstance(value, bytearray):
            value = bytes(value)

        assert isinstance(value, bytes), f"Unhandled TLV formatting for type : {type(value)}"

        tlv = bytearray()
        tlv += TlvSerializable.der_encode(tag)
        tlv += TlvSerializable.der_encode(len(value))
        tlv += value
        return tlv


def format_tlv(tag: int, value: Union[int, str, bytes, bytearray]) -> bytes:
    return TlvSerializable.serialize_field(tag, value)