Transport Layer Security (TLS) is a cryptographic protocol designed to provide communications security over a computer network. The protocol is widely used in applications such as email, instant messaging, and voice over IP, but its use in securing HTTPS remains the most publicly visible.
The TLS protocol aims primarily to provide security, including privacy (confidentiality), integrity, and authenticity through the use of cryptography, such as the use of certificates, between two or more communicating computer applications. It runs in the presentation layer and is itself composed of two layers: the TLS record and the TLS handshake protocols.
The closely related Datagram Transport Layer Security (DTLS) is a communications protocol that provides security to datagram-based applications. In technical writing, references to "(D)TLS" are often seen when it applies to both versions.TLS is a proposed Internet Engineering Task Force (IETF) standard, first defined in 1999, and the current version is TLS 1.3, defined in August 2018. TLS builds on the now-deprecated SSL (Secure Sockets Layer) specifications (1994, 1995, 1996) developed by Netscape Communications for adding the HTTPS protocol to their Netscape Navigator web browser.
Attributes
- Layer-5
- We encrypt with symmetric key algorithms.
- We need to exchange the symmetric key.
- Key exchange uses asymmetric key (PKI)
- Authenticate the server
- Extensions (SNI, preshared, ORTT)
- TLS 1.2 Handshake (two round trips)
- 1st round trip on what to use
- 2nd round trip on agreeing on that
- Diffie Hellman
- Send your part; the server will manage it.
- TLS 1.3 Improvements (one round trip and can be zero)
- TLS 1.2 and 1.3 are contents of the TCP layer.
