01 What ist the AMSCO Cipher?

Amsco Cipher – Kryptos and Cryptanalysis Information (thonky.com)

The AMSCO cipher method is a transposition/column swap cipher.
The number of columns is determined by the key.

The key may only consist of consecutive digits from 1 to 9, with each digit occurring only once.

The digits designate columns in which the input text is written alternately with one or two letters in columns. The ciphertext is then read out column by column using the key digits.