Logic Puzzles and Brainteasers

$$\text{Cryptogram Craziness}$$

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Today is Alan Turing’s birthday! Alan Turing was an English computer scientist and mathematician in the early to mid twentieth century. One of his greatest accomplishments was the development of an electromechanical machine that could decrypt the messages sent by the Germans during World War II. These messages were sent using Enigma machines, devices that encrypted information using a series of interchangeable rotors; Turing’s work allowed the Allies to intercept messages and significantly reduce the duration of the war in Europe and save millions of lives.

In general, ciphers are algorithms that allow for the encryption and decryption of information, typically using a key known only to the parties communicating the information; ciphers are especially useful for sending private messages in public settings.

The Content Team at Expii has developed their own cipher to pass notes amongst themselves (mainly to discuss what time they want to buy coffee) so that Po-Shen Loh cannot decipher their messages, even if he sees what’s written on the notes.

Po-Shen Loh has hired you as a spy to figure out what time the Content Team is buying coffee today. All you know is that the team encodes their messages using a table and a key and how they do it.

Each member of the Content Team has the following table memorized:

Suppose they want to encrypt the string POSHENLOH with the key TURING. They align the string and key horizontally and repeat the letters in the key as many times as needed:

They would then use the column of the letter in the string we want to encrypt and the row of the corresponding letter in the key to get the following encryption:

So the message written on the note is “DDFMORIDY.”