SSL (Secure Socket Layer) works by establishing a secure and encrypted connection between a client and a server to ensure the confidentiality, integrity, and authenticity of the data transmitted over the internet. Here’s a simplified explanation of how SSL works:
- Client Hello: The SSL handshake begins when a client initiates a connection to a server. The client sends a “Client Hello” message containing the supported SSL/TLS versions, encryption algorithms, and other parameters.
- Server Hello: Upon receiving the Client Hello, the server responds with a “Server Hello” message, selecting the highest SSL/TLS version and encryption algorithm that both the client and server support.
- Certificate Exchange: The server sends its digital certificate, which includes its public key, to the client. The certificate is typically issued by a trusted Certificate Authority (CA) and contains information to verify the server’s identity.
- Client Authentication (Optional): In some cases, the server may request the client to authenticate itself using a client certificate.
- Key Exchange: The client generates a random session key and encrypts it using the server’s public key obtained from its certificate. This encrypted session key is sent back to the server.
- Session Key Establishment: The server decrypts the encrypted session key using its private key. Both the client and server now have a shared session key to encrypt and decrypt the data exchanged during the SSL session.
- Secure Data Exchange: From this point onwards, the client and server use the shared session key to encrypt and decrypt all data transmitted between them, ensuring confidentiality.
- Data Integrity and Authentication: SSL also uses cryptographic algorithms to generate message authentication codes (MAC) to verify data integrity and ensure that the data received has not been tampered with during transmission.
By following these steps, SSL establishes a secure and encrypted connection, protecting sensitive information from eavesdropping and unauthorized access. It provides a secure channel for online transactions, secure browsing, and secure communication over the internet.