Talk:Transposition cipher
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[edit] This isn't Railfence
The system described under the section "Railfence" is not the Railfence system as I've usually seen it described.
The system described here is a columnar transposition, written down and read left-right. The Railfence system as I've always seen it used was based on a rising-and-falling pattern:
ABCDEF
| A | E | ||||
| B | D | F | |||
| C |
AEBDFC --jdege 19:00, 18 January 2007 (UTC)
- Yes, that's what I've understood it to be too. I've removed the section for now until we can clear it up. — Matt Crypto 19:09, 18 January 2007 (UTC)
I've done some websearching, and I've found that there are a number of sites that use "Railfence" as was used on this page:
- http://www.cs.trincoll.edu/~crypto/historical/railfence.html
- http://www.braingle.com/brainteasers/codes/railfence.php
OTOH, there are sites that refer to "Railfence" as I've always thought it was used:
The NSA's CryptoKids site describes Railfence only for height=2, in which case the two systems yield identical results:
As for who is right? Seems to me that write-by-coumn/read-by-row method that was described here is equivalent to the write-by-row/read-by-column that we see described in the section on Columnar Transposition. The older references seem to use Railfence as I had thought it meant. I'm working through Caxton Foster's "Cryptanalysis for Microcomputers", from 1982, and I'm absolutely certain that it uses Railfence to refer to an up-and-down transposition. And I'm pretty sure that Helen Gaine's "Cryptography", from 1939, uses the same.
The canonical answer on the Web, though, is probably the American Cryptogram Association, and they're solidly on the up-and-down side:
--jdege 19:26, 18 January 2007 (UTC)
I've just noticed that the current page contains a reference to the Rail Fence section, which has been removed. --jdege 23:52, 26 February 2007 (UTC)
I've edited Rail_Fence_Cipher to correct this misconception. If folks could look at it, check it for spelling, grammar, form, and fix what needs to be fixed, I'd appreciate it.
Perhaps, when it's right, we could consider using it to restore the Railfence section, here.
--jdege 02:30, 27 February 2007 (UTC)
[edit] Opening Sentence
"... a transposition cipher changes one character from the plaintext to another (to decrypt the reverse is done)."
If you read on, the writer's intention becomes clearer but the opening line is a bit of a muddle. Could I suggest: a transposition cipher changes the order of characters in a message. Example: THIS IS A TRANSPOSITION can become HTSI SI TA ARSNOPISITOIXN.
--Steve 00:18, 6 November 2007 (UTC)
- "... a transposition cipher swaps the positions of characters in the plaintext in predetermined way, so that the ciphertext constitutes a permutation of the plaintext."
- --jdege 15:39, 6 November 2007 (UTC)
Question
Who copied from who? The info on columnar transposition looks identical to that from this site. http://www.braingle.com/brainteasers/codes/columnartrans.php
-- anon 15:26, 12 January 2008
- If you look carefully, that website credits Wikipedia. — Matt Crypto 09:28, 13 January 2008 (UTC)
