1) Assume that we use the following notations:
Bpub, H(M) || Z(M) ))
This means A computes the Hash function of the message M asH(M), concatenates with the compressed value of M as Z(M),then encrypts the result using first the public key of B[KBpub ] and then encrypts the result with the privatekey of A [KApriv ]. A then transmits theresult to B.
Using these notations, indicate the message M sent by A to Butilizing the authentication and confidentiality of PGP.