def _activate_inbound(self):
block_size = self._cipher_info[self.remote_cipher]['<STR_LIT>']<EOL>if self.server_mode:<EOL><INDENT>IV_in = self._compute_key('<STR_LIT:A>', block_size)<EOL>key_in = self._compute_key('<STR_LIT:C>', self._cipher_info[self.remote_cipher]['<STR_LIT>'])<EOL><DEDENT>else:<EOL><INDENT>IV_in = self._compute_key('<STR_LIT:B>', block_size)<EOL>key_in = self._compute_key('<STR_LIT:D>', self._cipher_info[self.remote_cipher]['<STR_LIT>'])<EOL><DEDENT>engine = self._get_cipher(self.remote_cipher, key_in, IV_in)<EOL>mac_size = self._mac_info[self.remote_mac]['<STR_LIT:size>']<EOL>mac_engine = self._mac_info[self.remote_mac]['<STR_LIT:class>']<EOL>if self.server_mode:<EOL><INDENT>mac_key = self._compute_key('<STR_LIT:E>', mac_engine.digest_size)<EOL><DEDENT>else:<EOL><INDENT>mac_key = self._compute_key('<STR_LIT:F>', mac_engine.digest_size)<EOL><DEDENT>self.packetizer.set_inbound_cipher(engine, block_size, mac_engine, mac_size, mac_key)<EOL>compress_in = self._compression_info[self.remote_compression][<NUM_LIT:1>]<EOL>if (compress_in is not None) and ((self.remote_compression != '<STR_LIT>') or self.authenticated):<EOL><INDENT>self._log(DEBUG, '<STR_LIT>')<EOL>self.packetizer.set_inbound_compressor(compress_in())<EOL><DEDENT>
switch on newly negotiated encryption parameters for inbound traffic