Chaining random permutations



Hello group,

Given a source for truely random numbers, you can construct a truely
random permutation for blocks of a small size, say 16 bits, by
enumeration. You can use cipher block chaining to apply this
permutation securely to larger blocks of plaintext. If your plaintext
is suitably small, such that the chaining doesn't start to leak
information, wouldn't that make a secure block cipher? I'm not asking
for perfect secrecy, just for reasonable security.


Greets,
Ertugrul.


--
nightmare = unsafePerformIO (getWrongWife >>= sex)
http://blog.ertes.de/

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