One time Pad Reuse
Lt. Will Crypt Randomly, a member of the Sealand1 Navy, is in charge of sending secret messages to his country's ships using one-time pads (OTP).
Unfortunately, Will fell asleep and cannot remember which one-time pads he has already used and which are unused! The US Navy has intercepted four ciphertexts sent by Will.
The captured ciphertexts are available and also the course resources page.
(a) Explain why Lt. Randomly should be fired if he reused a OTP2. It turns out that Sealandians speak English and that the plaintext of the messages Will sent are in ASCII English.
(b) Were any of the four ciphertexts encrypted with the same pad?
(Hint: you will probably want to write a program that reads the ciphertexts and automates your analysis).
(c) Detail your algorithm in (b) to identify pad reuse and identify which ciphertexts were encrypted with the same pad.
(d) Decrypt one or more of the Sealand messages.