A MACHINE SOLUTION OF THE AMSCO CIPHER
Mike Barlow · Cryptologia · 1986
The AMSCO cipher is an incomplete-columnar transposition cipher that lends itself to machine solution. The regularity of the transposition makes it possible to write a computer program that will try all combinations of various keyword lengths, and to check for the presence of likely words (cribs) in the answers. If a genuine crib is available, such as those provided in examples in “The Cryptogram”, a positive answer can be determined. If no crib is available, then it is necessary to try the most popular words in the vocabulary. A 99 per cent success rate seems possible, without knowing either the keyword length or a crib word.