ref1=: ~.normalize alpha
ref2=: 'BGWKZQPNDSIOAXEFCLUMTHYVR'
ref3=: 'PLAYFIREXMBCDGHKNOQSTUVWZ'

   ref1 bifid normalize 'attack at dawn'
DQBDAXDQPDQH
   ref1 difib ref1 bifid normalize 'attack at dawn'
ATTACKATDAWN
   ref2 bifid normalize 'flee at once'
UAEOLWRINS
   ref2 difib ref2 bifid normalize 'flee at once'
FLEEATONCE
   ref2 bifid normalize 'attack at dawn'
EYFENGIWDILA
   ref2 difib ref2 bifid normalize 'attack at dawn'
ATTACKATDAWN
   ref3 bifid normalize 'The invasion will start on the first of January'
VRSYXSIYTMQVIRSKISLPVLDTCKRTCAIVTMATCEX
   ref3 difib ref3 bifid normalize 'The invasion will start on the first of January'
THEINVASIONWILLSTARTONTHEFIRSTOFIANUARY
   (_81{.123{.a.)bifid 'The invasion will start on the first of January'
TgqhpqpqxzpxfqzoKqhxw/O3eWH53BYw`+Be8F1
   (_81{.123{.a.)difib(_81{.123{.a.)bifid 'The invasion will start on the first of January'
TheinvasionwillstartonthefirstofJanuary