Redefence

History

The Redefence cipher is a variation of the Railfence transposition cipher which was used by both sides during the American Civil War. It was first described in the Feb-Mar and Jun-Jul 1952 editions of the American Cryptogram Association (ACA) magazine The Cryptogram by ACA member RED E. RASER though it wasn't given the name of Redefence until the Jul-Aug 1965 edition.

Description

The cipher is formed by writing plaintext letters in a zig-zag pattern across a number of rows or 'rails' starting on any row. The text is then read off across the rows in the order determined by a keyword or number to produce the ciphertext.

Example

Rails: 4

Starting offset: 0

Order: CASH (2143)

Plaintext: I started out with nothing, and I still have most of it.

2 I E I H D L O T

1 S T D W T T I N I L H M S I

4 T R O T H O N A S I A E T F

3 A U N G T V O

Ciphertext: STDWT TINIL HMSII EIHDL OTAUN GTVOT ROTHO NASIA ETF

Solving

Solving method: Brute force search.

After selecting the Redefence cipher, the cipher period can be selected from the Setup drop down menu. The default setting of 0 means that all periods in the range 3 to 10 will be tested.