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Re: One-Time Pad software?
From: Atom Smasher <atom () smasher org>
Date: Sat, 3 Feb 2007 21:27:18 -0500 (EST)

On Sat, 3 Feb 2007, FocusHacks wrote:

Thanks for the information, guys. As far as one-time pads being the same length as the cleartext, I know how it works. If a spy of days past had a very long message to encrypt, he may need to use more than one page of his paper pad. By the same token, if I have a large binary file to encrypt, but have stored several small files of random data to use as my pad (and the receiving party has the same files and knows in which order to utilize them), I would expect a tool to be able to handle the task. It's not convenient to generate a perfect-length pad file for every ciphertext message I wish to transmit. Looping a 20k file over a larger cleartext message would not be OTP, it'd be a simple running key algorithm that'd be a lot easier to break with simple heuristics. Sure, it'd be a 20 kilobyte key, a lot less trivial than looping an eight-letter lowercase word as a key, but it wouldn't be nearly as good as a genuine OTP.
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a few CD-Rs can hold plenty of pad/key information. many paper shredders are advertised as being capable of shredding a CD... has anyone looked into the feasibility of putting a shredded CD back together?


The reason I'm thinking small files is because on solid state media (for instance, volatile storage in a PDA), it's easy to securely erase one file at a time, which is much like burning the piece of paper you just used. correctly implemented, OTP is both computationally trivial to perform, yet "perfectly secret", so long as the pad remains secure.
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it's actually *not* easy to erase one file at a time on PDAs, flash drives, etc. that discussion was about a week or so ago.


--
        ...atom

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