1. Introduction

1. Introduction

The primary goal of the TLS protocol is to establish an authenticated, confidentiality- and integrity-protected channel between two communicating peers. The TLS protocol is composed of two layers: the TLS record protocol and the TLS handshake protocol. However, TLS must run over a reliable transport channel -- typically TCP [RFC0793].

There are applications that use UDP [RFC0768] as a transport and the Datagram Transport Layer Security (DTLS) protocol has been developed to offer communication security protection for those applications. DTLS is deliberately designed to be as similar to TLS as possible, both to minimize new security invention and to maximize the amount of code and infrastructure reuse.

DTLS 1.0 [RFC4347] was originally defined as a delta from TLS 1.1 [RFC4346], and DTLS 1.2 [RFC6347] was defined as a series of deltas to TLS 1.2 [RFC5246]. There is no DTLS 1.1; that version number was skipped in order to harmonize version numbers with TLS. This specification describes the most current version of the DTLS protocol as a delta from TLS 1.3 [TLS13]. It obsoletes DTLS 1.2.

Implementations that speak both DTLS 1.2 and DTLS 1.3 can interoperate with those that speak only DTLS 1.2 (using DTLS 1.2 of course), just as TLS 1.3 implementations can interoperate with TLS 1.2 (see Appendix D of [TLS13] for details). While backwards compatibility with DTLS 1.0 is possible, the use of DTLS 1.0 is not recommended, as explained in Section 3.1.2 of [RFC7525]. [DEPRECATE] forbids the use of DTLS 1.0.