Abstract: The present disclosure provides methods for secure communication. In an example method, an optical line terminal (OLT) sends a first message to an optical network unit (ONU), where the first message includes a first key algorithm, a certificate of the OLT, and a public key of the OLT, and the first key algorithm is a key algorithm supported by both the OLT and the ONU. The ONU verifies the certificate of the OLT, and after the verification succeeds, the ONU determines a shared key based on the first key algorithm and the public key of the OLT. The ONU sends a second message to the OLT, where the second message includes a certificate of the ONU and a public key of the ONU. The OLT verifies the certificate of the ONU. After the verification succeeds, the OLT determines the shared key based on the first key algorithm and the public key of the ONU.

Abstract: This disclosure provides a valve stem of a needle throttle valve and the method of fabricating the same. The valve stem includes ahead part, a body part, a washer, a first solder sheet and a second solder sheet. The washer is made of metal. The first solder sheet is placed between the head part and the washer, and the second solder sheet is placed between the body part and the washer. The head part, the washer and the body part are jointed together by the melted first solder sheet and the melted second solder sheet.

Abstract: This disclosure provides a valve stem of a needle throttle valve and the method of fabricating the same. The valve stem includes ahead part, a body part, a washer, a first solder sheet and a second solder sheet. The washer is made of metal. The first solder sheet is placed between the head part and the washer, and the second solder sheet is placed between the body part and the washer. The head part, the washer and the body part are jointed together by the melted first solder sheet and the melted second solder sheet.