Transport Layer Security vs Secure Socket Layer

Transport Layer Security vs Secure Socket Layer


Both TLS (Transport Layer Security) and SSL (Secure Socket Layer) are protocols which are used for encryption and authentication when communication happens over an insecure network. SSL is usually known as the predecessor of TLS and at most of the time they both are used in combined.

How SSL Differs from TLS

SSL- Initiate a secure connection with the server using the method called "By Port" in which connecting to a specific port should be secure connection.The server is configured in a way, at first a secure connection should use to connect to those ports.

TLS- The secure connection is initiated using the method called "By Protocol". In this method first the client send a simple insecure hello first to the server. After the client hello if the handshake between the client and the server is successful the secure connection is established. Otherwise ignored.

How SSL Handshake works

As I mentioned above SSL can also be called as By Port communication. In the SSL protocol ports in the server can be configured to be used for secure connections. Below is a diagram which shows how the SSL Handshake happens.

In the handshake process,

  • The client who is willing to communicate with the server sends a simple hello request to the server’s socket which is configured for SSL communication
  • Server sends the server hello response to the client with additional information. Those information includes
    • Server Certificate
    • Server Public key
    • SSL Protocol version
    • Server Cipher
    • Client Certificate Request (Optional)

  • Client receive the server response and then check if the Public key is trustable and if the Public key of the server is valid further communication happens, otherwise connection is terminated.
  • If the public key of the server is valid then the client set the keys for communication and the cipher to be used in the communication.
  • When the server get the request it initiates the communication and the handshake ends
  • After these steps the client and the server can communicate using the agreed cipher and the exchanged keys between them


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