# 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.