Double transposition cipher help
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Tagged: transposition cipher
- This topic has 8 replies, 6 voices, and was last updated 5 months, 2 weeks ago by Mattyrat2027.
9th December 2022 at 10:47 am #87490BrickyBoyParticipant
Is there really a good way of trying to decrypt a double transposition cipher without guessing the keys? Because if you try and re-arange it (to decrypt it) it wont work because it’s still encrypted again? How can you know you are on the right track?
[If this is a general double transposition then you are in trouble, but maybe it is not quite that hard? Harry9th December 2022 at 12:50 pm #87492f6exbParticipant
I wasted a lot of time because “double trouble” misleads me. Then a small light turned on.10th December 2022 at 6:16 pm #87497BobDParticipant
Factors, cribs, and a little persistence.10th December 2022 at 6:17 pm #87506FlappyasdfParticipant
What do you mean by that?10th December 2022 at 6:17 pm #87507BrickyBoyParticipant
I’ve tried almost every common cipher at this point.
Its not ceaser (i mean, i didnt expect it to be), its not vignerre (also a bit unlikely, but still), its not normal transposition i dont think, its not collumnal transposition (whatever that is) i dont think, its not double transposition cipher. Just… what is it. Im not expecting a proper answer, but could you atleast point me in the right direction? I dont want to spend all night on a cipher it isnt again. (Like what i did with the double transposition). And i saw another one of your comments: how does 8B help?10th December 2022 at 6:18 pm #87512IcyBeeParticipant
Search for “double transposition” in Wikipedia.
The first sentence of the Cryptanalysis section was all I needed!10th December 2022 at 6:18 pm #87513Mattyrat2027Participant
Are you implying that it has been encrypted twice, but not with 2 columnar transposition ciphers?
That’d be an interesting concept considering the text has no substitution, so it’d have to be another cipher that keeps all the letters…
Or maybe I’m grasping at thin air10th December 2022 at 9:57 pm #87515f6exbParticipant
If you solved 8B, you can solve 9B.
Look at Harry’s tips in the second paragraph.11th December 2022 at 2:20 pm #87521BobDParticipant
Replying to Flappyasdf’s question #87506: Factoring 1869 gave only a few different values for the number of columns to check. The crib given in Tips got me almost home; however, the number of repeated letters in this crib still left several possible permutations. The scattering of expected cribs throughout the message quickly sorted out the final column order. The pattern contained in the order of columns indicated that there may have been simpler ways to decrypt the message.11th December 2022 at 2:22 pm #87527Mattyrat2027Participant
Unfortunately I didn’t. I do think I sort of understand how it worked, but I have no way to successfully carry it out, besides the time consuming process of by hand.
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