AMSCO transposition — The grid is filled with alternating runs of one and two letters, so the columns come out different lengths before the key even reorders them.
Alternating 1-2 letter chunks written into a grid, columns read in key order.
A worked example§
Encrypting a sample with the cipher itself, at build time:
MEET ME BY THE OLD CLOCK TOWER AT DAWNKey: ZEBRA
produces the ciphertext
BDCWWNTEOKTDEEHOCAMELTOAMYTLERThis example is generated by running the cipher when the page is built, and the round trip is checked, so it always matches what the solver does.
How it is broken§
Two unknowns at once — the column order and whether the first cell took one letter or two — and the uneven columns mean the attacker cannot tell where in the ciphertext each column begins.
History and context§
A twentieth-century American Cryptogram Association construction, designed specifically to defeat the standard columnar attack.
See also§
Columnar transposition · Rail fence · Skip / scytale · Route transposition · Myszkowski transposition
Browse every cipher in the Transposition ciphers family, read the history of codebreaking, or return to the wiki main page.
Frequently asked questions§
How is the AMSCO transposition broken?
Two unknowns at once — the column order and whether the first cell took one letter or two — and the uneven columns mean the attacker cannot tell where in the ciphertext each column begins.
What key does the AMSCO transposition use?
permutation keyword. The keyspace is unbounded in practice.
How much ciphertext do I need?
At least 30 characters for this solver to attempt it; short messages can be readable and still not be proof.
Can I break a AMSCO transposition on this page?
Not with the browser build, which targets the common puzzle families. The desktop version searches it: see the Windows app page.