Chapter 2 WRESTLING BETWEEN SAFEGUARD and ATTACK
Some terms:
encryption, encipherment, decription, decipherment, cryptographic algorithms, symmetric (shared-key) cryptosystem, asymmetric (public-key) cryptosystem, principal (entity, agent, user), bad guys (attacker, adversary, enemy, intruder, eavesdropper, impostor ), Active Attacker, Insider, Threat Model, Malice.
Entity Authentication (The Liveness of An Identified Pricles ", s is intended Object of the communication,
Key-Encryption Key, Long-Term Key, Session Key, Short-Term Key.
Perfect encryption with notation {m} k an ideal encryption algorithm
i) without the key k, the ciphertext {m} K Doesn't Provide Any Cryptanalysis Means for Finding The PlainText MSG M.
II) {m} K and maybe TOGETHER WITH SOME KNOWN INFORMATION About The Plaintext Msg M Donot Provide Any Cryptanalysis Means for Finding The Key K.
III) without the key k, even with the knowledge of the placext m, it is impossout being detetd by the recipient during the time of decryption.
Dolev-Yao Threat Model
In this model, Malice Has The Following Characteristics:
He can obtain any message passing through the networkHe is a legitimate user of the network, and thus in particular can initiate a conversation with any other userHe will have the opportunity to become a receiver to any pricipalHe can send messages to any principal by impersonating any other Pricipal
Therefore, in this model, all messages on the network can be treated by the MALICE.
However, there are still something that Malice can't do:
Malice can not guess a random number which is chosen from a sufficiently large space.Without the correct secret (or private) key, Malice can not retrive plaintext from given ciphertext, and can not create valid ciphertext from given plaintext with respect to the perfect encryption algorithm.Malice can not find the private component, ie., the key K.While Malice have control of a larget public part of our computing and communication environment, in general, he is not in control of many private areas of the computing environment, such as accessing the Memory of a Principal's Offline Computing Device.Security Properties for Authenticated Key Establishments
After the end of the protocol run:
Only Alice and Bob (or perhaps a principal who is trusted by them) should know K. confidentiality Alice and Bob should know that the other principal knows K. "spot of" Alice and Bob should know that K is newly generated. Freshness
