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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def scan(self, result):
        '''
        Validate signature results.
        '''
        if self.enabled is True:
            if result.valid is True:
                if result.description.lower().startswith(self.SIGNATURE_DESCRIPTION) is True:
                    # Read in the first 64 bytes of the suspected encrypted
                    # uImage header
                    fd = self.module.config.open_file(result.file.path, offset=result.offset)
                    encrypted_header_data = binwalk.core.compat.str2bytes(fd.read(64))
                    fd.close()

                    # Decrypt the header
                    decrypted_header_data = self._hilink_decrypt(encrypted_header_data)

                    # Pull out the image size and image name fields from the decrypted uImage header
                    # and add them to the printed description.
                    result.size = struct.unpack(b">L", decrypted_header_data[12:16])[0]
                    result.description += ", size: %d" % (result.size)
                    # NOTE: The description field should be 32 bytes? Hilink seems to use only 24 bytes for this field,
                    #       even though the header size is still 64 bytes?
                    result.description += ', image name: "%s"' % binwalk.core.compat.bytes2str(decrypted_header_data[32:56]).strip("\x00")

                    # Do some basic validation on the decrypted size and image
                    # name fields
                    if result.size > (result.file.size - result.offset):
                        result.valid = False
                    if not all(c in string.printable for c in result.description):
                        result.valid = False