# Method Crypto.Substitution()->set_ACA_K1_key()

Method set_ACA_K1_key

  ``this_program` set_ACA_K1_key(`string` `key`, `void`|`int` `offset`, `void`|`array`(`string`) `alphabet`)`

Description

  Sets the key according to ACA K1 key generation. The plaintext alphabet is prepended with a keyword `key` that shifts the alphabet positions compared to the cryptogram alphabet. The plaintext alphabet is then reduced with the characters in the keyword. It is also optionally rotated `offset` number of steps.