Challenge 8B – Hints
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Hello everyone,
Recently, I have been trying to figure out what type of cipher 8B is, and I am wondering if it is possible for it to be encoded in more than one. Therefore, I would really appreciate it if someone could clarify whether this could be the case, so that I can spend my time decoding the ciphertext knowing this.
Thank you!
I feel that this is a polybius cipher, but solving the ciphertext using a polybius cipher directly gives some gibberish which no matter what I do doesn’t give useful output, whether I use a shift or a polyaphabetic cipher afterwards. As such I have a feeling that the ciphertext is first changed slightly and then solved using a polybius, but I’m not entirely sure how.
I’m also very stuck and haven’t come close to cracking it yet, so don’t read anything into what I’m saying; I’m just trying to share ideas.
Assuming that it is derived from some kind of 5*5 Polybius Square that is read as two numbers at a time (maybe someone could confirm), it can be re-written as a substitution cipher. For example, the first part of the ciphertext would go from ‘143351’ to ‘DMU’ when put directly into the square. If you repeat this for the whole ciphertext, you end up with some other ciphertext that is easier to work with because it is in ASCII characters rather than pairs of numbers.
However, what you do from here (if this is even the correct first step) is beyond me. If you have done Part A (I haven’t), maybe try the same process for that.
It doesn’t seem to be any kind of monoalphabetic substitution as the IoC is two low. Again, this is all purely speculation; please do correct me if I am barking up the wrong tree.
If it gets let in, I’d like to give the hint:
The step you mentioned is a correct step, but it isn’t the correct first step
I’ve solved 8A already, and I can say that it doesn’t have any clues for this. The only idea I have is that the plaintext is likely to start with “MY DEAR CHARLES”, but getting that from the polybius just makes it more confusing. I would like to hear if anyone else has any suggestions.
I think the hint for 8A carries on for 8B in a way, if that helps
Does anyone have any other hints?
So what I am getting here is there are at least two steps in cracking this cipher. One of which is the Polybius Square. But is the square a simple alphabet in order or does it involve a keyword or anything?
The step you mentioned is a correct step, but it isn’t the correct first step
I did it with five minutes to spare before the deadline! Thanks for the subtle hint.
Well done to everyone who has attempted this one; it is very tricky.
To anyone still going for it, this thread might be your best source of guidance. Also keep checking the case files for any pointers. Good luck!
@Cypher1_HGS #98803 you need to experiment with what you suggest in your last sentence. Keep going, the fun is in try lots of different variations and finally getting a reward for your effort.
I started with polybius. And I tried so many different combinations – nearly gave up and then suddenly it hit me!
I got it. Many thanks to Moses.
I’m still really stuck. I’ve taken the hints available into my python code but when I get my string of text and put it into a frequency analyser, I notice “z” always doesn’t have any uses. I think the second cipher is some form of cipher that rearranges the letters, but I don’t know which, can someone point me in the right direction?
I know there is a step before the polybus, but is there also a step after?
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