1.

(a) Discuss how realistic or unrealistic the assumptions are concerning the attacker's capabilities and knowledge in Attack 2.6.

(b) (i) Modify Attack 2.6 so that Mallory replaces Alice's message with one of her own choosing.

(ii) Explain why Bob will be unaware of this replacement.

(iii) Is Mallory capable of doing this even if Alice is offline?

(iv) If Alice signs a document for Mallory and sends it to her, can Mallory then forward that document to Bob and say that this is a signed document from Alice to Bob?

(c) Suppose that Alice does not sign $$h(m)$$ in Protocol 2.5, so that $$h(m)$$ is only used to check that the message $$m$$ has not been altered in transit. Describe the revised protocol and sketch how Attack 2.6 changes.