The symmetric ciphers

Werner Koch wk at
Wed Oct 30 21:59:25 CET 2013

On Wed, 30 Oct 2013 20:25, pkk at said:

> If we have plenty of randomness available, we could do this a

Entropy (which should be at the core of every CRNG) is a scarce
resource.  Thus a one time pad is not going to work because you need
true random at the same size of the message.

> XOR the message M with a random one-time pad P to obtain N. Encrypt P
> with A, and N with B.
> The drawback is that this doubles the lenth of the message.

And that you need a way to securely convey the OTP to the recipient.

The soviets had severe problems to do that during WWII and later and
resorted to double use the one time pads.  That was one of the origins
of the UKUSA alliance aiming and succeeding at breaking there messages
(project VENONA).



Die Gedanken sind frei.  Ausnahmen regelt ein Bundesgesetz.

More information about the Gnupg-users mailing list