Developing 3D-Playfair Cipher algorithm using structure rotation

3D-Playfair cipher is a multiple letter encryption cipher. Trigraphs (combination of 3 characters) of the plaintext are treated as single unit and converted into corresponding cipher text trigraphs and vice-versa. Classical Playfair Cipher supports English alphabets with limitation that only one alphabet “i” or “j” will be considered at a time. 3D-Playfair Cipher came into focus to eliminate this limitation. In addition to that 3D-Playfair Cipher also overlooks the limitation of similar fashion encryption of diagrams and its reverse diagrams. 3D-Playfair cipher supports all 26 English alphabets {A-Z}, 10 digits {0-9} and 28 special characters including { ! “ " # $ % & ` +, - . / : ; ( ) <; = > ? @ [ ] ^ _ | }. The theme of this research is to enhance the security of text files that contains alphabets, numerals and special characters. In this approach we developed a structure rotation concept on key matrix of 3D-Playfair cipher using random key to achieve the objective. Random sequences are generated through Linear Feedback Shift Register due to its simplicity and better performance.