Challenged (forgive the pun) by this week’s part B cipher? Ada has asked Charles to use a Vigenere cipher to encrypt his reply. These ciphers were introduced in the XVIth century, but despite their antiquity they remained in use until the XIXth century when Babbage and Kasiski independently devised systems to break them.
The work by encrypting letters in a message using different Caesar shifts depending on the position of each letter. Ada has asked Charles to use her personal key, and you could take a guess what that might be, but if you want a hand, then take a look at Case File 5.3, where Ada has started to work on the cipher. Perhaps you can see what Ada’s “personal key” might be!
Good luck,
