Shulou(Shulou.com)06/01 Report--

SSL secure Sockets layer:

Is a protocol that provides a secure channel between two machines, which has the function of protecting the transmission data to identify the communication machine.

The SSL protocol consists of two layers:

SSL recording Protocol (which is based on reliable transport protocols (such as TCP) and provides support for high-level protocols with basic functions such as data encapsulation, compression, encryption, etc.

SSL handshake protocol (which is based on SSL recording protocol and is used for identity authentication, negotiation of encryption algorithms, exchange of encryption keys, etc.) before the actual data transmission begins.

The main purpose of ssl handshake is to get the session key. The handshake itself belongs to asymmetric encryption. When the session key is obtained, the future data transmission will be carried out using symmetric algorithm.

SSL handshake process:

1. The client sends client hello messages (including ssl version, encryption algorithm list, random number)

two。 The server responds to server hello messages (including confirmation of ssl version, confirmation of encryption algorithm, random number, server certificate)

3. After receiving the message, the client first checks the validity period of the certificate, certificate chain, CRL, etc., confirms the identity, and the client generates random numbers again, then encrypts the three random numbers using the certificate public key and sends them to server

4. After receiving the message, the server uses the private key to decrypt the encrypted information to get three random numbers and generate the session key.

Communication using ssl is divided into one-way authentication and two-way authentication, which depends on whether the client has its own certificate.

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