Message Encryption and Public Key Encryption

Message encryption C symmetric 1 encryption) source A Destination B M E D M E K (M) K K or. (K,M) Confidentiality is assured here in the s/m Authentication is assured here in the s/m 2. Public Key Encryphon - confidentiality (Assume A is the sender and B is the Source A receiver) Deshiration M 5 D M pub E(PUb,M) PRb of 3. Public Key Eneryption - Authentication &digital signature source A Destination B M 5 D M F (PR M) PR Pua

4. Public key Eneryption - authentication Confidentiality, and digital signature M E P M E PRa EPR.(M) PUb E.PUb/Efra (M)] RRb D M EPRa(M) PUa PRa, Pua authentication and digital signature is provided PUB, PRb confidentiality is achieved 9