Supported TLS versions¶
TLS 1.2 is currently the most wide-spread version, although its successor, version 1.3, has been in use for some time as well. It's not recommended to use older versions due to security concerns.
What is TLS
TLS is a cryptographic protocol that enables secure and encrypted connection between users and servers. It provides not only encryption, but also authentication and data integrity check - to ensure that the transported data haven’t been altered in transit. Apart from securing data transfer via HTTP, it can be used to secure other services as well, such as e-mail (SMTP and IMAP).
TLS 1.2 which was published in 2008 is currently the most commonly used version supported by virtually all websites (99.9 % in Sep 2023). In comparison to its predecessors, it introduced the implementation of more advanced algorithms and ciphers. The level of security TLS 1.2 provides, depends to a high degree on the chosen settings - especially of said ciphers and algorithms.
The newest version, TLS 1.3 has shortened the handshake process (during which the client and the server agree on the parameters of the communication and exchange keys) and limited the number of cipher suites. Even though it was published in 2018, it hasn’t yet become as wide-spread as its predecessor (64.8 % in Sep 2023).
Older versions (1.0 and 1.1) are already deprecated and shouldn’t be used anymore since they make use of outdated algorithms such as MD5 and SHA-a and are susceptible to a variety of attacks, e.g., Poodle or Beast and major browsers don’t support them anymore.