Advantages and Disadvantages
Advantages
- Has a better mixing of letters than some ciphers. (Rail Fence Cipher)
- The main benefit that transposition cipher have over substitution cipher is that transposition cipher can be applied more than once. (This is the Double Transposition.)
Disadvantages
- Can easily be deciphered if it was a small message.
Irregular Case
Double Column Transposition
- The only difference between regular and irregular columnar transposition is that instead of random letters you put blanks.
- Double column transposition takes the already encrypted text and cipher it again using a different keyword. This makes decrypting the text extremely difficult.
- This transposes the columns twice.
In this picture, the highlighted part is where the random letters would be if it was a Regular Case.
Citation
- http://practicalcryptography.com/ciphers/columnar-transposition-cipher/
- http://www.braingle.com/brainteasers/codes/columnartrans.php
- http://crypto.interactive-maths.com/columnar-transposition-cipher.html
Introduction
Regular Case
- Any Spare spaces are filled with nulls / random letters
- Use your messages and write them in rows of fixed length
- Messages read out column by column
- Three Different types of Columnar
Regular, Irregular And Double
- Both the width of the rows and the permutation of the columns are usually defined by a keyword
- The permutation is defined by the alphabetical order of the letters in the keyword
Columnar Transposition