Reply To: Challenge 10B
@Chinchinchilla
For a standard 4 square encryption the letters chosen are normally ‘J’ or ‘Z’ – ‘J’ because it is near the bottom of letter frequencies used in the English language and the letter ‘I’ can be used to retain the meaning of the text and the letter ‘Z’ because it is at the bottom of the letter frequencies used in the English language. If you are using a hill climbing attack and chose the letter(s) incorrectly then you should still be able to decrypt the message, although you will only get a 99% correct result with a few words that are obviously wrong making it possible to correct the grids.