Cryptographic Key Agreement Protocols Clause Samples

Cryptographic Key Agreement Protocols. ‌ A key agreement protocol is a series of steps used by two or more parties in order to se- curely agree on a shared secret, such as a session key, in an unprotected network. Key agreement protocols differ from key transport protocols in which the whole key is trans- mitted over a secure channel from one entity to another. For instance, key transport and secure channels are used by trusted third parties such as a CA or a KGC in issuing pri- vate data to users. In key agreement, on the other hand, entities contribute information jointly to establish a shared secret. A protocol that establishes a shared key between two entities is called a two-party key agreement protocol. Sometimes it’s also useful to consider three parties, and thus the protocol is called a tripartite key agreement protocol. If a protocol has more than three participants, it is called a group or conference key agreement protocol. Examples of tripar- tite and group key agreement protocols can be found in [32] and [22, 55] respectively. Furthermore, if a key agreement protocol exchanges information between its partic- ipants, it is said to be interactive. It is also possible for a protocol to be non-interactive, although more usual in the identity-based setting in which public keys of entities are al- ways known. Identity-based non-interactive protocols will always suffer from the session key escrow property and are thus rarely used in practice. For the remainder of this thesis, only interactive two-party key agreement protocols will be discussed.