5
votes
2answers
3k views

When using symmetric key encryption, do we need to sign?

Say we're using a shared key between two parties, that has been distributed using public key encryption, is it still necessary to sign any data that's encrypted using the shared key? Or is it enough ...
26
votes
4answers
13k views

How to achieve non-repudiation?

If I have a message that I need to send to another person, how do I achieve non repudiation ? Is digitally signing the message sufficient ?