[Narrator] The question for the challenge is you're given 2 intercepted cipher texts, C1 and C2.
You can see those both below, and you know that they were both encrypted using a one time pad
using the same key.
They're also both messages in standard English.
Your goal is to figure out what the 2 plain text messages were.
You can enter these in any order, and it should be clear to you that
which one is which can't really be determined, but figure out what the 2 plain text messages
corresponding to the 2 intercepted cipher texts are, and I should mention that
you can assume that both messages are in English
and were encoded using string.to.bits that maps English to sequences of bits.
I'm not going to provide an answer to this one,
but I'll give you a hint how to get started if you are stuck,
and that would be to try common English sequences of letters t-h-e would be a good one to try,
and assume that probably appears somewhere in at least 1 of the quotes,
and you can try t-h-e at each of the starting positions, and then assume that's in say message 1.
You're going to guess cipher text 1 is t-h-e encrypted with a key,
then you can compute the key from this that gives you what the likely key is,
XORing string.to.bits of t-h-e with the corresponding part of that cipher text,
and then you can XORing out the guest key from the corresponding part of message 2.
If that looks like something that might be part of an English message,
well, then, that's a good guess, and you can work on from there
and start expanding the letters that you've guessed to see ones that produce reasonable results for both cipher texts.
This is a fairly manual process; if you wanted to do this more automated way,
well, then, you'd use properties of English to automate this kind of guessing and expansion for you.
