Timeline for Deciphering “easy” ciphers without hints
Current License: CC BY-SA 3.0
10 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Oct 19, 2015 at 21:39 | comment | added | UsuallyNot | I've computed the "most likely" keys with 81 characters, however the keys are just a scrumbled mix of those characters ("ILSSJMMESAVVVVSVVIIVWGEMIIMGVBGMVVYFGCVVVVAKQGCZVUTVWIMVPUVUIGUURIRGHRNHRUYIAUSII" for example). However using this (or similar, also calculated keys) doesn't even reveal parts of words. Currently I don't know how to progress further. I've also started some 3rd party script trying to guess the key and print decrypted text - however there is no meaningful text yet... | |
| Oct 19, 2015 at 17:55 | vote | accept | UsuallyNot | ||
| Oct 19, 2015 at 17:25 | comment | added | UsuallyNot | Well, I'm a little bit unfamilliar with stackexchange, but could you open up a chat room, so I could post the cipher without making it easily searchable for others? (I think the cipher shouldn't be shown to everyone as it's a personal challenge) | |
| Oct 19, 2015 at 15:10 | comment | added | tylo | Well, without the actual challenge, it's quite difficult to point in the right direction. If the only "flashy" value is 81, and 3,9,27 are just average like the rest, then it is unlikely that 3,9 and 27 are correct key sizes (Factors of the correct key size don't show deviating values, just the multiples). A Vigenere cipher with a key of length 81 sounds unlikely, but not impossible. But anyway, you have found some characteristic, that means you're on the right track. | |
| Oct 19, 2015 at 11:49 | comment | added | UsuallyNot | I've computed & tested the chi-squared values for Key length 9 and 27 so far (81 is in the do). For length 9 I couldn't decrypt a meaningful plaintext. I also altered some values in the Key which had similar chi-square values. However I can't even recognize parts of words yet. Any Ideas? | |
| Oct 18, 2015 at 17:54 | comment | added | UsuallyNot | I've coded a java program in the meantime which calculates the IC values. However the only flashy value in the statistic has been with period 81. As this only means the maximum period will likely be 81, 27 and 9 could also fit (factors of 81). Is my assumption right? In the meantime I'm heading towards chi-squared statistic to figure out the key letters. | |
| Oct 16, 2015 at 14:32 | comment | added | tylo | I'd suggest trying to figure out the block size first. With the aurocorrelation method you can figure that out without knowing anything about the alphabet, as long as it is not uniform distributed. | |
| Oct 16, 2015 at 7:09 | comment | added | UsuallyNot | I'm unsure about having the right alphabet for this cipher and asked another, independent question: crypto.stackexchange.com/questions/29870/…. Once I've got that faulty reasoning of mine solved, I'm able to go on. Also, I corrected the alphabet seen in my cipher. | |
| Oct 15, 2015 at 12:06 | comment | added | UsuallyNot | Thanks a lot, tylo! I'll have a deeper look into your suggestions after work. I've tried some "Vigenére breakers" before because I haven't had the time to go trough it manually. Will do that asap and update you here. | |
| Oct 15, 2015 at 11:58 | history | answered | tylo | CC BY-SA 3.0 |