One-time-pad

[Deic Lone]

I found this question on an exam past paper and couldn't think of a justified solution.

A message is double encrypted by using the one time pad twice with two keys k1 and k2. Show that this procedure is no more secure than using a single encryption and calculate the key k3 that this double encryption corresponds to.

Any ideas??

[Nicholas Jordan]

That's ( non-mathematically ) 100% == 100% iow idempotent

flyin rat's carcass in a ketchup factory is indistinguishable from any other ( same ) ...

possibly a trick question or one designed by a mathematician teaching math to lead in to some mathematical property, splitting nuances that are not of utility in practical cryptography. Usualy the human factor far exceeds such matters, that may not be what your instructor had in mind for a reply.