Corby,
I *had* to forward this to you. Can you give him the answer, or are you bound by an NDA? I can't remember.
Corby
Unfortunately, I am bound by an NDA. However, I am not violating the NDA by saying that Craig is correct. There is no way to do a one-time pad except by doing a one-time pad. In other words, it is not possible to generate synchronized, truly random key streams at remote locations non-algorithmically. One-time pads have a property that no other encryption scheme has. If I am an attacker and I somehow gain access to all of the key material and all of the plaintext that two communicating parties have so far used, I am still unable to decipher the next transmission. *Only* one-time pads have this property, and there is no way to achieve it without negotiating a key stream out of band. OTPs also have some other properties that are more mathematical in nature. For instance, the probability of getting any particular bit of plaintext from a given ciphertext is equal to the raw probability of getting that plaintext by itself. In other words: p_P(x_i | c) = p_P(x_i) where P is the plaintext space, x_i is the plaintext, and c is the ciphertext. Furthermore, p_K(K) = 1/|K| which means that all keys are used with equal probability, irrespective of plaintext and ciphertext. Hope this helps! - Mark -
Forwarded message:
From firewalls-owner@GreatCircle.COM Thu Oct 26 03:39:33 1995 X-Delivered: at request of corby on doom X-Authentication-Warning: miles.greatcircle.com: majordom set sender to firewalls-owner using -f From: Craig Bishop <csb@connect.com.au> Message-Id: <199510260745.RAA16385@koromiko.off.connect.com.au> Subject: One Time Pad encryption over the Internet, securely? To: firewalls@greatcircle.com Date: Thu, 26 Oct 1995 17:45:13 +1000 (EST) X-Mailer: ELM [version 2.4 PL21] Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: firewalls-owner@GreatCircle.COM Precedence: bulk
I was contacted and asked whether I was interested in software which which used a one time pad for encrytion.
It comes from Elementrix an Isreali company is offering encrypted email, ftp and what they call "personal firewall" software.
This software uses a One Time Pad via a patent pending method. I am no encryption expert and the information available is limited but it would seem to me that there is no way to do this over the internet securely.
See, http://www.elementrix.co.il/
Cheers, Craig
-- Craig Bishop - Internet Security Analyst csb@connect.com.au http://www.connect.com.au/people/csb/
-- Mark Chen chen@intuit.com 415/329-6913 finger for PGP public key D4 99 54 2A 98 B1 48 0C CF 95 A5 B0 6E E0 1E 1D