Symmetric Key Cryptography Technique
- Substitution Technique
- Transposition Technique
Transposition Technique :-
1. Rail Fence Technique - It involves writing plain text as sequence of diagonals and then reading it row by row to produce cipher text.
For example- "Defend the east wall" is a plain text and Key is 3 then,
It can be written as - DNETLEEDHESWLFTAA
2. Vernam Cipher (One-Time-Pad) - The Vernam cipher also called as One time pad, is implemented using a random set of non-repeating characters as the input cipher text. If an input cipher text for transposition is used, it is never used again for any other message. The length of input cipher text is equal to length of plain text.
For example- "Defend the east wall" is a plain text and Key is 3 then,
It can be written as - DNETLEEDHESWLFTAA
2. Vernam Cipher (One-Time-Pad) - The Vernam cipher also called as One time pad, is implemented using a random set of non-repeating characters as the input cipher text. If an input cipher text for transposition is used, it is never used again for any other message. The length of input cipher text is equal to length of plain text.
- use alphabets in plain text as number like a=0,b=1,.....z=25
- do same in input cipher text
- add these numbers
- if sum is greater than 26, subtract 26 from it
- translated these numbers into alphabet and you get the output.