a) Alice just generated a new pair of public and private RSA keys (pkA , skA ) = ((N, e), d) and would like to start a private conversation with Bob. How can Alice interact with Bob and exchange a symmetric key? Describe a key exchange protocol between them which is secure against an eavesdropper adversary.
b) Fully specify a Man-in-The-Middle (MiTM) attack attack against the key exchange protocol you described above.
c) Assume now that Alice and Bob are very old friends and that Bob already knows a public key pkA owned by Alice. How can you improve the above protocol in such a way that Bob can detect the presence of a MiTM? Can Alice also detect the presence of a MiTM?
In part a) I defined a protocol using the idea behind D Hellman, so this is vulnerable to MiTM. However, I dont know how to work out part c