Transport Layer Security (TLS)

TL;DR: A further development of the SSL protocol, which is used to encrypt data transmissions on the Internet

Transport Layer Security (TLS) is a cryptographic protocol developed to ensure the security and integrity of data during transmission between computers over a network. TLS is the successor to the Secure Socket Layer (SSL) protocol and offers improved security measures. It is mainly used to secure internet connections by encrypting communication between web browsers and web servers.

Main objectives of TLS:

1. Encryption: TLS encrypts the data that is transferred between the client (e.g. a web browser) and the server (e.g. a website). This protects the data from interception and manipulation by third parties.
2. Integrity: TLS ensures that the data cannot be changed or manipulated during transmission without this being detected. This is achieved using cryptographic hash functions.
3. Authentication: TLS enables the authentication of communication partners. This is done by using digital certificates that ensure that the data actually originates from the expected server.

How TLS works:

The TLS process comprises several steps, which together are referred to as the TLS handshake:

1. Client Hello: The client initiates the connection and sends a message (Client Hello) to the server. This message contains information about the supported encryption methods and the TLS version of the client.
2. Server Hello: The server responds with a message (Server Hello) containing the encryption method and TLS version selected by the server. The server also sends its digital certificate issued by a trusted certification authority (CA).
3. Certificate examination: The client checks the server certificate against the list of trusted certification authorities. If the certificate is confirmed as valid, the handshake continues.
4. Key exchange: The client and server agree on a session key that is used to encrypt all subsequent communication. This can be done using various key exchange methods, such as the Diffie-Hellman key exchange.
5. Encrypted connection: Once the handshake has been completed, communication between the client and server is encrypted using the agreed session key. Both parties use this key to encrypt and decrypt data that they send and receive.

Advantages of TLS:

1. Secure data traffic: TLS protects the data during transmission and ensures that sensitive information such as passwords, credit card numbers and personal data cannot be intercepted or manipulated.
2. Trusted authentication: TLS uses digital certificates to ensure that the client is actually communicating with the intended server and not with an impostor.
3. Wide application: TLS is widely used in many Internet protocols, including HTTPS (for secure web connections), SMTP (for secure email communication), and others.

Applications of TLS:

• HTTPS: TLS is the basis for HTTPS (Hypertext Transfer Protocol Secure), which is used for secure communication between web browsers and web servers.
• e-mail: Many e-mail services use TLS to ensure the security of e-mail communications.
• VPNs: Some Virtual Private Network (VPN) protocols use TLS to ensure the security of data transmission.
• VoIP: Voice over IP (VoIP) services use TLS to ensure the security of voice communications.

Conclusion:

Transport Layer Security (TLS) is an essential protocol for securing communication over networks, especially the internet. By providing encryption, data integrity and authentication, TLS protects sensitive data and ensures that it is transmitted securely and reliably. TLS is the current standard for secure communication and has largely replaced SSL.