On Sep 26, 2017, at 11:14 AM, \0xDynamite <dreamingforward@gmail.com> wrote:

AFAICT, it is UNBREAKABLE if the keysize is at least half the size of
your plaintext.

My understanding is that the keysize ought to be as long as the message to
be encrypted.

Well if they don't know the key length, then using somewhere between
1/3 and 2/3 should make it unbreakable.


It's not a one time pad, and not secure, if the key is smaller than the clear text. 

And yes, it is unbreakable...   UNLESS you try to reuse the keys!!!

Hmm, but THEY don't know if you re-used them.   So it would take how
many ciphertexts messages to figure that out?

Marxos


I've mentioned this before in regards to OTP, and I think Jim just mentioned it -

https://en.m.wikipedia.org/wiki/Venona_project