Columnar Transposition Introduction The Columnar Transposition cipher is very simple and easy to implement cipher. It is a transposition cipher that follows a simple rule for mixing up the characters in the plaintext to form the cipher text. How it works In a columnar transposition, the message is written out in rows of a fixed length, and then read out again column by column, and the columns are chosen in some scrambled order. Both the length of the rows and the permutation of the columns are usually defined by a keyword. * Uses a two dimensional array Text is placed in rows * Columns are transposed * Columns are read out as ciphered text What advantages and disadvantages does it have Columnar Transposition Advantages * The columnar transposition technique of encryption is easy to understand and implement but still complex to break by brutal force attack or cryptanalysis. * Columnar transposition method get enhances as the key size is increased and by re applying the same technique. * The hacker or the intermediate person cannot break this code unless otherwise he knows the method. Diffusion * Immunity to insertions * Impossible to decrypt the encrypted cipher text without the knowledge of the key and the length of it and the no. of columnar transpositions that were made. Columnar Transposition Disadvantages The strength of stream cipher * Speed * Error propagation * Slowness of encryption * Sensitive to lost or increased characters What impact does it have on the cryptographic models of today Why it is important Example How to construct a columnar transpose Destruction
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