def serialize_encryption_context()

in src/aws_encryption_sdk/internal/formatting/encryption_context.py [0:0]

• 35 lines of code
• 9 McCabe index (conditional complexity)

def serialize_encryption_context(encryption_context):
    """Serializes the contents of a dictionary into a byte string.

    :param dict encryption_context: Dictionary of encrytion context keys/values.
    :returns: Serialized encryption context
    :rtype: bytes
    """
    if not encryption_context:
        return bytes()

    serialized_context = bytearray()
    dict_size = len(encryption_context)

    if dict_size > aws_encryption_sdk.internal.defaults.MAX_BYTE_ARRAY_SIZE:
        raise SerializationError("The encryption context contains too many elements.")

    serialized_context.extend(struct.pack(">H", dict_size))

    # Encode strings first to catch bad values.
    encryption_context_list = []
    for key, value in encryption_context.items():
        try:
            if isinstance(key, bytes):
                key = codecs.decode(key)
            if isinstance(value, bytes):
                value = codecs.decode(value)
            encryption_context_list.append(
                (aws_encryption_sdk.internal.str_ops.to_bytes(key), aws_encryption_sdk.internal.str_ops.to_bytes(value))
            )
        except Exception:
            raise SerializationError(
                "Cannot encode dictionary key or value using {}.".format(aws_encryption_sdk.internal.defaults.ENCODING)
            )

    for key, value in sorted(encryption_context_list, key=lambda x: x[0]):
        serialized_context.extend(
            struct.pack(
                ">H{key_size}sH{value_size}s".format(key_size=len(key), value_size=len(value)),
                len(key),
                key,
                len(value),
                value,
            )
        )
        if len(serialized_context) > aws_encryption_sdk.internal.defaults.MAX_BYTE_ARRAY_SIZE:
            raise SerializationError("The serialized context is too large.")
    return bytes(serialized_context)