An employee of your company files a complaint with a security administrator. While sniffing network traffic, the employee discovers that financially confidential emails were passing between two warehouse users. The two users deny sending confidential emails to each other. You need to allow for non-repudiation and prevent network sniffers from reading the confidential mail. What should you do?

A. Implement transport encryption and authentication hashing.
B. Implement transport encryption and legal mail hold.
C. Implement legal mail hold and authentication hashing.
D. Implement transport encryption and digital signatures.

D
Explanation: To allow for non-repudiation and prevent network sniffers from reading the confidential mail, you should implement transport encryption and digital signatures. Transport encryption protects all information transmitted over the network. Digital signatures ensure that the source of the email can be verified.
A legal mail hold would require more administrative effort than is necessary and would not provide non-repudiation. Authentication hashing would only ensure that authentication traffic is verified to be unchanged and therefore valid.