[Requirement] Some [Comments] Although some XKMS applications have a specific requirement to support Non-Repudiation, the ability to repudiate requests and responses is acceptable in many applications. [Security Issue] 
Transitive Authentication
C o n f i d e n t i a l i t y
R e q u e s t A u t h e n t i c a t i o n
R e s p o n s e A u t h e n t i c a t i o n
T r a n s i t i v e A u t h e n t i c a t i o n
M e s s a g e C o r r e s p o n d e n c e
R e q u e s t R e p l a y
D e n i a l o f S e r v i c e