Diffie-Hellman exchange protocol

In Diffie-Hellman exchange protocol, assume that p=541 and g=10. If the cloud client chooses A=13 and the cloud server chooses B=17, what is the established secret key K? Why can the session key K provide security?

Consider the threat of “theft/breach of proprietary or confidential information held in key data files on the system.” One method by which such a breach might occur is the accidental/deliberate e-mailing of information to a user outside of the organization. A possible countermeasure to this is to require all external e-mail to be given a sensitivity tag (classification if you like) in its subject and for external e-mail to have the lowest sensitivity tag. Discuss how this measure could be implemented in a firewall and what components and architecture would be needed to do this.