3
votes
1answer
90 views

How online document signing services guarantee non-repudiation?

There is a number of services online like RightSignature or SignHub that will let you sign online legally binding documents. I understand how documents can be signed digitally and this can guarantee ...
0
votes
1answer
227 views

Secure API access over SSL using oauth token

On the project that i'm currently working, we authenticate the clients by username and password. In this system each user has a key which is calculated from his password. However, we want to provide ...
4
votes
2answers
2k 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 ...
24
votes
4answers
10k 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 ?