# @ca - code array
# @kp - key phrase
# $c  - caesar shift (big hint here)
# %p2 - short for p2C - plaintext to CIPHERTEXT hash
# %C2 - short for C2p - CIPHERTEXT to plaintext hash
# $k  - key (one letter of the key alphabet)
# $t  - text
# $h  - hash reference
# $r  - result