TRANSPOSITION CIPHER In the transposition technique the positions

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TRANSPOSITION CIPHER In the transposition technique the positions of letters/numbers/symbols in plain text is

TRANSPOSITION CIPHER In the transposition technique the positions of letters/numbers/symbols in plain text is changed with one another. 1 2 3 4 5 6 4 2 1 6 3 5 M E E T M E T E M E E M A F T E R P E F A P T R A R T Y Y R A T Visit for more Learning Resources

TRANSPOSITION CIPHER TECHNIQUES 1. Rail Fence Cipher 2. Columnar Transposition Simple Columnar Transposition Double

TRANSPOSITION CIPHER TECHNIQUES 1. Rail Fence Cipher 2. Columnar Transposition Simple Columnar Transposition Double Columnar Transposition

1. RAIL FENCE CIPHER • In this method plain text is written downwards on

1. RAIL FENCE CIPHER • In this method plain text is written downwards on “rails of fence “ , starting a new column when bottom is reached. • Algorithm: 1. First write down plain text message as a sequence of diagonals. 2. Read the plain text written in first step as a sequence of rows.

1. RAIL FENCE CIPHER Example: Plain text: come home tomorrow Cipher text: cmhmtmrooeoeoorw

1. RAIL FENCE CIPHER Example: Plain text: come home tomorrow Cipher text: cmhmtmrooeoeoorw

1. SIMPLE COLUMNAR TRANSPOSITION • In this method the message is written in rows

1. SIMPLE COLUMNAR TRANSPOSITION • In this method the message is written in rows of fixed length and then read out column by column • Column are selected in some scrambled order. • The number of columns are defined by the length of key. • Algorithm: 1. Write the plain text message row by row in a rectangle of predefined size. (length of key) 2. Read the message column by column according t the selected order thus obtained message is a cipher text.

1. SIMPLE COLUMNAR TRANSPOSITION Key: ZEBRAS plain text: welcome home Order : 6 3

1. SIMPLE COLUMNAR TRANSPOSITION Key: ZEBRAS plain text: welcome home Order : 6 3 2 4 1 5 Cipher text: MLOEHCMWEOE

2. DOUBLE COLUMNAR TRANSPOSITION • Single columnar transposition can be attack by guessing possible

2. DOUBLE COLUMNAR TRANSPOSITION • Single columnar transposition can be attack by guessing possible column lengths. • Therefore to make it stronger double transposition is used. • This is simple columnar transposition technique applied twice. • Here same key can be used for transposition or two different keys can be used.

2. DOUBLE COLUMNAR TRANSPOSITION • First apply simple columnar transposition Key: ZEBRAS plain text:

2. DOUBLE COLUMNAR TRANSPOSITION • First apply simple columnar transposition Key: ZEBRAS plain text: welcome home Order : 6 3 2 4 1 5 Cipher text: MLOEHCMWEOE

2. DOUBLE COLUMNAR TRANSPOSITION Cipher text 1: MLOEHCMWEOE Order : 6 3 2 4

2. DOUBLE COLUMNAR TRANSPOSITION Cipher text 1: MLOEHCMWEOE Order : 6 3 2 4 1 5 Final Cipher Text: COELWEOMMHE

Substitution Cipher Transposition Cipher A substitution technique is one in which the letters/number/symbols of

Substitution Cipher Transposition Cipher A substitution technique is one in which the letters/number/symbols of plain text are replaced by other letters/numbers/symbols. In the transposition technique the positions of letters/numbers/symbols in plain text is changed with one another. It is easy to understand. It is difficult to understand. Methods: 1. Caesar's Cipher 2. Mono-Alphabetic Cipher 3. A Homophonic Substitution Cipher 4. A Polygram Substitution Cipher 5. A Polyalphabetic Substitution Cipher 1. e. g. Vigenere Cipher 6. One time Pad(Vernam Cipher) Methods: 1. Rail Fence Cipher 2. Columnar Transposition Simple Columnar Transposition Double Columnar Transposition For more detail contact us

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