Re: Non-Scalar Cryptography - The Emporor is stark naked.

austin.obyrne@xxxxxxxxxxxxxx writes:

[...]

Does this mean you have a computerised working one-time pad ?

No, it means that OTP is simple, but (outside of some niche
applications) useless.

Take the usual XOR of bytes system, then it's 5 minutes work to write
a program that takes any two of {key, plaintext, ciphertext} and
produces the third. (Maybe 10 or 15 minutes, I guess, depending on
the environment. It's easier to get at bytes and do XOR with some
environments than with others.)

The tricky part is (as discussed last time) key management. If I can
send n bytes of key securely, then I may just as well send my n bytes
of text securely and not bother with encrypting it at all.

There are some situations where the premise makes sense: maybe you can
take a key with you, and then later I send the encrypted message.

Or maybe I can send key and message through two different paths such
that it's very unlikely that someone can get both. (That's more
usually called secret splitting, I think, and usually you want some
general form where you split the secret into X parts and you want it
to be reproducible with any Y or more of those parts---that kind of
thing. AFAIK vector techniques are commonly used for this (they are
in descriptions of it, anyway---maybe not in reality).)

Whatever. In no cases is an implementation of the basic OTP algorithm
of any interest: it's all in how you manage the keys. And managing
the keys is intrinsically hard by the nature of the thing. That's why
you (almost) never want to use OTPs.

And (as we said last time) if your algorithm relies on the key being
the same size as the plaintext, then your algorithm has the same
problems as OTP.

And your algorithm is more complex than OTP, so your algorithm loses
(since OTP has perfect security---maybe yours does, too, but there's
no value in looking).

[...]

.

Relevant Pages

  • Re: attacking a re-used OTP // is it possible if it is changed with a random key each time ?
    ... securely transmitted daily, to generation new OTP by transposition, ... The algorithm will always be known. ... to develop something that is secure. ... can a new designation of the embedding for the next set of messages be ...
    (sci.crypt)
  • Re: Simple Unbreakable (Sipher Idea)
    ... > Probably that was too simple, of cause the entropy, from which the OTP ... In the algorithm description I ... >> is not perfect security in the OTP sense but is way way less and this ... > artificially slowing down decryption by changing the limiting factor ...
    (sci.crypt)
  • Re: quantum computing
    ... very fast (Shor's algorithm is one type of search). ... grover unstructured search algorithm is only a square root speedup, ... Nothing works against OTP since any message is a potentially valid mesage. ... once the entire plaintext is know it is possible to recover the key ...
    (sci.crypt)
  • Re: Simple Unbreakable (Sipher Idea)
    ... Probably that was too simple, of cause the entropy, from which the OTP ... In the algorithm description I ... decryption by requiring high amounts of RAM is just weird." ... artificially slowing down decryption by changing the limiting factor ...
    (sci.crypt)
  • Re: Use of Pseudo Random Generators for One Time Pad?
    ... > used to generate the OTP is not known to the enemy then the p-OTP is as safe ... > as a real OTP. ... And if the OTP generating software creates an algorithm from ... > among the infinite possibilities, uses that algorithm to generate the OTP ...
    (sci.crypt)