tran is a program by William Setzer and Carl Ellison to perform
a bytewise transposition of its input, on a block-by-block
basis.  Blocksize is 8192 bytes.

It's not a cipher, strictly speaking, because it does not
take a user-specified key.  Instead, it uses a simple but
clever autokey scheme.  The autokey is correctly computed
from the input regardless of whether the input has been transposed.

tran is self-inverting; tran|tran is a null filter.

(Notes by mrr@ripem.msu.edu   3 May 1993)
