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(<EOL>"<STR_LIT:C>", self._cipher_info[self.remote_cipher]["<STR_LIT>"]<EOL>)<EOL><DEDENT>else:<EOL><INDENT>IV_in = self._compute_key("<STR_LIT:B>", block_size)<EOL>key_in = self._compute_key(<EOL>"<STR_LIT:D>", self._cipher_info[self.remote_cipher]["<STR_LIT>"]<EOL>)<EOL><DEDENT>engine = self._get_cipher(<EOL>self.remote_cipher, key_in, IV_in, self._DECRYPT<EOL>)<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(<EOL>engine, block_size, mac_engine, mac_size, mac_key<EOL>)<EOL>compress_in = self._compression_info[self.remote_compression][<NUM_LIT:1>]<EOL>if compress_in is not None and (<EOL>self.remote_compression != "<STR_LIT>" or self.authenticated<EOL>):<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