# Method Crypto.Substitution()->set_ACA_K2_key()

Method set_ACA_K2_key

  ``this_program` set_ACA_K2_key(`string` `key`, `void`|`int` `offset`, `void`|`array`(`string`) `alphabet`)`

Description

  Sets the key according to ACA K2 key generation. The cryptogram alphabet is prepended with a keyword `key` that shifts the alphabet positions compared to the plaintext alphabet. The cryptogram alphabet is then reduced with the characters in the keyword. It is als optionally reotated `offset` number of steps.