SSL (Secure Socket Layer) or TLS (Transport Layer Security), as the protocol is named since version TLSv1, permits mutual authentication of two communicating applications and, in addition, guarantees confidentiality, integrity, and authenticity of the application data exchanged. Client/server systems can thus communicate via TLS without running the risk of exchanged data being intercepted or forged. The use of TLS is transparent for the protocols and applications involved.
TLS implements authentication, data integrity, and data confidentiality with the aid of two subordinate protocols:
TLS Record Protocol
TLS Handshake Protocol
The TLS Record Protocol defines the format used for transferring data. The TLS Handshake Protocol enables the TLS client and TLS server to authenticate themselves to each other and to exchange encryption algorithms together with the cryptographic key before an Application Layer protocol transfers the first data.
In interNet Services the implementations are based on the OpenSSL-Toolkit. At the time this manual went to print, Version 3.0.15 of the OpenSSL-Toolkit was used. The protocol versions supported are TLSv1.2 and in several cases also TLSv1.3.