Viewing Single Post From: Substitution Revisited!

Viewing Single Post From: Substitution Revisited!
jdege	May 17 2008, 11:23 AM
Elite member Posts: 263 Group: Admin Member #246 Joined: December 7, 2006	The biggest problem with the sort of transpositions you're doing is that you're always doing the same transpositions. You need to make your transpositions vary with the key. Are you familiar with the columnar transposition? You start with a keyword, and write your message out, left to right, top to bottom, in columns under the keyword. Then you read it off in columns, top to bottom, in alphabetic order of the keyword. Code: `S E C R E T T H I S I S A S E C R E T M E S S A G E IEEHS MEIRS RRCST ATGSE A` For a double transposition, you do this twice, with different keywords: Code: `M E S S A G E I E E H S M E I R S R R C S T A T G S E A SRSER AESAM CSIIT ESTHR G` Double transposition was considered a secure cipher, in WWI, for low-volume traffic. You needed several messages with the same length to break it, which only happened during times of high volume. One other thing. You're reversing the letters within each word. Then you're reversing the entire message. This has the effect of simply reversing the order of the words: Code: `THIS IS THE MESSSAGE SIHT SI EHT EGASSEM MESSAGE THE IS THIS` That's not likely to confuse anyone who tries to crack the substitution.
	When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

Substitution Revisited! · General