Double transposition cipher help

[BrickyBoy]

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? Harry

[f6exb]

I wasted a lot of time because “double trouble” misleads me. Then a small light turned on.

[BobD]

Factors, cribs, and a little persistence.

[Flappyasdf]

What do you mean by that?

[BrickyBoy]

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?

[IcyBee]

Search for “double transposition” in Wikipedia.
The first sentence of the Cryptanalysis section was all I needed!

[Mattyrat2027]

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 air

[f6exb]

@Mattyrat
If you solved 8B, you can solve 9B.
Look at Harry’s tips in the second paragraph.

[BobD]

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.

[Mattyrat2027]

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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