Known Key secrecy Sample Clauses

Known Key secrecy. Each run of a key agreement protocol between two entities A and B should produce a unique secret key; such keys are called session keys. A protocol should still achieve its goal in the face of an adversary who has learned some other session keys. This KAP provides the known key secrecy as each session key is unique for each value of the session secret keys. For example if the adversary came to know about the common key of the three entities A, B and C , that is 𝐾 = 𝑎1𝑎2𝑎3𝑏3𝑏2𝑏1which involves the session secret keys (𝑎1, 𝑏1) of A, (𝑎2, 𝑏2) of B and (𝑎3, 𝑏3) of C. For the next communication they are going to choose the secret keys different from these keys. Thus the other session keys cannot be found out by the adversary as it involves session secret keys of each entity. Suppose any one of the communicating parties say A’s long term private key is disclosed he may impersonate A to other entities, since it is precisely the identity of A. In this KAP the key compromise impersonation clearly impossible as the communicating parties sign their public keys by using the digital signature algorithm established between them each round. An adversary cannot take part in the communication between A,B and C. Unknown key share: An unknown key-share attack on an authenticated key agreement protocol is an attack whereby an entity A ends up believing it shares a key with another entity B and although this is in fact the case that B mistakenly believes the key is instead shared with an entity C ≠ A. This scenario is impossible in this KAP as the entities A, B and C are using the DSA to sign their public keys. If suppose an adversary pretends as A to B then he faces the difficulty of getting the signature of A and sign A’s public key. On verification B finds that it does not come from A and rejects the public key. Thus this KAP is secure against the unknown key share attack. Key Control: Neither entity should be able to force the session key to a preselected value. As the common shared key is arrived with the contribution of each entity, this case will never arise. Thus this KAP provides no key control attribute.

Known Key secrecy. Each run of the protocol should result in a unique session key. Key generated in one protocol round is independent and should not be exposed if other session keys are compromised.

Known Key secrecy. A and B choose random a א ܼכ and b א ܼכ respectively in each protocol run; they will have distinct session key in each run. Thus, compromising the secret keys will not affect the next session key to be generated. ௤ ௤

Known Key secrecy. Suppose a session key established in a session between two protocol principals (denoted by A and B ) is disclosed the adversary ( denoted by E) is unable to learn other session keys established in any other session . this attribute is also called key independence , which means that session keys of different sessions are computationally independent of each other . This is regarded as the standard requirement for key agreement protocols. The established session key has not been modified by an adversary or equivalently for a key agreement protocol; key integrity means that if a session key is accepted by any principal, it must be a known function of only the inputs of the protocol principals.