sesjonsciphernøkkel

A sesjonsciphernøkkel, often translated as session encryption key, is a temporary, randomly generated cryptographic key used for encrypting data during a specific communication session. Unlike long-term keys that might be stored and reused for extended periods, session keys are designed for a single, limited duration. This ephemeral nature is a core security principle.

The primary purpose of a session key is to provide confidentiality and integrity for data exchanged between two parties, such as a web browser and a server. When a secure connection is established, for example, using protocols like TLS/SSL, a negotiation process occurs. During this negotiation, the parties agree on a cipher suite and then generate a unique session key. This key is then used to encrypt all subsequent data transmitted within that specific session.

Once the communication session ends, whether due to a timeout, explicit closure, or a defined period, the session key is discarded. This practice significantly enhances security by limiting the exposure of any single key. If an attacker were to compromise a session key, they would only be able to decrypt data from that particular session, rather than gaining access to all past or future communications that might have used a different key. The generation of a new, random session key for each new session ensures that even if one session key is compromised, subsequent sessions remain secure.