An employee of a 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.
Which of the following security practices would allow for non-repudiation and prevent network sniffers from reading the confidential mail? (Select TWO).
A . Transport encryption
B . Authentication hashing
C . Digital signature
D . Legal mail hold
E . TSIG code signing
Answer: A,C