TLS (Transport Layer Security) works over TCP (Transmission Control Protocol) by establishing a secure communication channel between a client and server. When TLS is used over TCP, it integrates with TCP’s reliable, connection-oriented communication to ensure data integrity, sequencing, and reliable delivery. The TLS handshake process initiates the secure connection, where the client and server negotiate cryptographic algorithms, exchange keys, and authenticate each other using digital certificates. Once the TLS handshake is complete, data transmitted over the TCP connection is encrypted and decrypted using session keys derived from the exchanged secrets, ensuring confidentiality and protection against eavesdropping or tampering.
TLS works step by step to secure communication between a client and server over a network. The process begins with the client sending a “ClientHello” message to the server, specifying supported TLS versions, cryptographic algorithms, and session parameters. The server responds with a “ServerHello” message, selecting a mutually supported cipher suite and generating a session key. The server also sends its digital certificate to the client for authentication. The client verifies the server’s certificate and generates a premaster secret, encrypts it with the server’s public key, and sends it to the server. Both parties derive session keys from the premaster secret and use them to encrypt subsequent data transmissions, ensuring confidentiality, integrity, and authenticity of communication.
TLS primarily operates over TCP due to TCP’s reliability, sequencing, and connection-oriented nature, which are essential for secure communication requiring guaranteed data delivery and order. TLS leverages TCP’s capabilities to establish and manage secure connections, encrypting data payloads to protect against interception and manipulation while ensuring reliable transmission between clients and servers over IP networks.
TLS can technically work over UDP (User Datagram Protocol) but is less commonly used in practice. UDP is connectionless and does not guarantee reliable delivery or sequencing of data, which poses challenges for implementing TLS. However, in certain scenarios where lightweight, real-time communication is prioritized over reliability (such as VoIP or online gaming), Datagram Transport Layer Security (DTLS), a variant of TLS designed for UDP, may be used. DTLS incorporates mechanisms to address UDP’s characteristics, such as handshake retransmissions and sequence number verification, to provide secure communication over unreliable UDP networks.
TLS works with HTTP (Hypertext Transfer Protocol) to provide secure communication between clients (such as web browsers) and servers (such as websites). When TLS is used with HTTP, it is commonly referred to as HTTPS (HTTP Secure). HTTPS encrypts HTTP requests and responses using TLS, protecting sensitive data like login credentials, financial transactions, and personal information from interception by malicious actors. TLS secures HTTP communications by establishing a secure TLS session through a handshake process, verifying server identity with digital certificates, and encrypting data transmitted over the HTTP connection to ensure confidentiality, integrity, and authenticity of web interactions.