TheCodeBreakers
He began with a checkerboard filled out to ten
columns with Greek letters:
6
Chase wrote his coordinates vertically, so that his sample plaintext,
Philip, appeared like this:
133131 959899
He then multiplied the lower line by 9, obtaining the result:
133131 8639091
This he restored to literal form by resubstituting back in his
checkerboard, 8 (by itself) = L, j, or T, then 16 = N, 33 = s, 39 = i, and so
on, with the final ciphertext
LNSl4>IX.
Chase proposed other means of transforming the bottom row, such as
adding a repeating key or giving the logarithm of the row, and pointed
out that even more intricate processes might be used. "But the simpler
cypher, provided it is effectual, is the better," he wisely concludes. The
Chase systems grant a fairly hermetic security; they are, besides,
relatively simple to operate. Yet cryptologic history shows no one ever
having used them, even though they are far superior to many systems
annaabi.ee 
