In symmetric key cryptosystem, assume that Alice and Bob have set up a common key Kab. This key is only known to Alice and Bob. (1a) Can we achieve data origin authentication?

Mastercard managers are motivated to increase (1) the number of individuals who have and use a mastercard credit card, (2) the number of banks and other clents who issue mastercards to customers and/or employees, and (3) the number of locations that accept mastercard payments. discuss how mastercard could use its data warehouse to it expand each of these customer bases.