A cryptographic key used for one communication session or bounded context. Its freshness and association with the intended peers need authentication; the fact that it arrives in an encrypted message does not by itself establish either property.
Conveying a session key selected by one participant to its intended users with the required secrecy and authentication. It differs from jointly contributing to a key-agreement calculation.

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A session key is a temporary encryption key used to encrypt and decrypt information exchanged during a single communication session between two parties. This method ensures that each session has its own unique key, which helps enhance security. Session keys are primarily used in various cryptographic protocols, including Transport Layer Security (TLS), Secure Sockets Layer (SSL), and other secure communication systems.