Explain why an anonymous key exchange protocol cannot be secure against a computationally unbounded adversary.
This is a homework, and my analysis is poor, but I try, this is what I answered:
In this case as is defined that our adversary is has no computationally limits, unlike real life, and it’s taken away most of the impediments that actually occurred. We can consider that the Key Generator algorithm, has an input a value R (it is conceptualized as a random number generator), and produces a public key, PK, and a secret SK. A computationally unbounded adversary, possibly will consider all possible inputs of R, and eventually will find out which one generates the PK, so that’s the way for him knowing the SK, because if that R creates the PK therefore can creates the SK, and can be used for decrypting the message. Besides if the private Kay was generated correctly, it will be able to fulfill the next property: DSK(EPK(M))=M Consequently, we can concluded that the Anonymous Key Exchanged cannot be secure against a computationally unbounded adversary.