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### Course: Computer science theory>Unit 2

Lesson 3: Cryptography challenge 101

# Clue #3

### So you take a stroll to the train station...

You don't see anything under the bench...
What's that over there?
Clue #3
Transcript of the above message: ``` 44541134541123335344541242 43424432514121231131135315 54425442444243443251415343 54324234411125513553341342 43225343114454345343225134 31421432513412533412155415 34513351444411225144425442 44441534512355154321345111 13112123514254315333214243 51445315341434512542531544 335154325341443 (cut off) 43513544 ```

## Want to join the conversation?

• I tried getting the most out of the message, just to be easier for decrypting.
44541134541123335344541242434244325141212311311353155442544244424344325141534354324234411125513553341342432253431144543453432251343142143251341253341215541534513351444411225144425442444415345123551543213451111311212351425431533321424351445315341434512542531544335154325341443...(missing)...43513544
• Thanks! This'll make decrypting it a lot easier!

I finally figured it out!
• I understand this is a polybius square, and it seems there's no "Z", as per reading the questions here, but what's the arrangement of letters? I've solved clues 1 and 2, and they're all plain English, but don't hint about the letter arrangement... Does it have to do with clue 2's keyword?

Assuming the message begins with "start", I've figured out four letters in (x, y) format, such as 54 being (5, 4), but can't figure out how to do the rest of the letters.
• If you draw the polybius square, and enter the letters for 'start' in the positions that you think they belong in, the arrangement of these letters in the square should give you an idea as to the overall pattern of how letters are arranged in the square. (Hint: What is the pattern that r,s,t make in this square ? If you had to guess, where would you put q? what about p?)
• So this one is multiple layers of code... unless this time they don't use the message format we have been using for our advantage?? what about the address number has to mean something! what do u think?
• I've been trying this for a while now and can't seem to get anything to work out. It must be multiple encryptions (i.e. the square and polyalphabetic or something) but everything I try comes up with nothing. The thing I can't get though is that the last message they only said about adding the square. If they have changed to other methods or other keys surely they would have mentioned that? Other wise the person who just received this message would be in the same position as we are?
• Wow! I watched the video and *'BAM'* , I got the answer for the 3rd clue. The same exact thing is shown in the video! HINT - There are only numbers from 1-5 in the message. But as in the 1st clue @Noble Mushtak told me that the door number ( 250 ) had something to do with the decryption . I wonder if *'3815'* is also some kind of clue?? If anybody knows a decryption method related to 3815 , please tell me!
• I wondered if this was relevant too. I didn't find anything, but I didn't catch the 250 thing either. I wouldn't worry about it too much.
• Did anybody get a bunch of random letters for the last word? I have the entire message but the last 5 letters are nonsense.
• I did until I realized that the '3' on the end of the line above is half a letter and stripped it out. Without that, it's a recognizable word. Try just '43513544'.
• I hope randomly clicking helps in getting the points :)
What is a good Hint for this?
• does this give us another encrypted message or have i done it wrong?
• Remember that in coordinates, the horizontal coordinate is placed before the vertical coordinate...and that this ISN'T coordinates.
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I saw the polybius square in breaking bad(tv show), the lady first counted the row number then the column number, and that's the reasonable one, as you go 5 successive letters each count. You here do it the contrary and I don't know why you do that. You count the column first then the row. Why?

Secondly, most of the results appearing on google show that in order to decrease the number of the letters to 25 you put i and j in one square. You here just removed the z. How should I know that? (I only knew from the comments) and why?

Overall, I love these challenges. I don't only solve them, I make programs that do so. And I hope to see more of these challenges.
• OK, so on the Clue 3 image, I see a ton of lightning bolts instead of numbers.

I cannot tell if those are supposed to be 3's or 5's.