A Novel Generic Session Based Bit Level Encryption Technique to Enhance Information Security

📝 Abstract

• In this paper a session based symmetric key encryption system has been proposed and is termed as Permutated Cipher Technique (PCT). This technique is more fast, suitable and secure for larger files. In this technique the input file is broken down into blocks of various sizes (of 2 power n order) and encrypted by shifting the position of each bit by a certain value for a certain number of times. A key is generated randomly wherein the length of each block is determined. Each block length generates a unique value of number of bits to be skipped. This value determines the new position of the bits within the block that are to be shifted. After the shifting and inverting each block is XORed with SHA 512 digest of the key. The resultant blocks from the cipher text. The key is generated according to the binary value of the input file size. Decryption is done following the same process as the technique is symmetric.

💡 Analysis

• In this paper a session based symmetric key encryption system has been proposed and is termed as Permutated Cipher Technique (PCT). This technique is more fast, suitable and secure for larger files. In this technique the input file is broken down into blocks of various sizes (of 2 power n order) and encrypted by shifting the position of each bit by a certain value for a certain number of times. A key is generated randomly wherein the length of each block is determined. Each block length generates a unique value of number of bits to be skipped. This value determines the new position of the bits within the block that are to be shifted. After the shifting and inverting each block is XORed with SHA 512 digest of the key. The resultant blocks from the cipher text. The key is generated according to the binary value of the input file size. Decryption is done following the same process as the technique is symmetric.

📄 Content

(IJCSIS) International Journal of Computer Science and Information Security,
Vol. 3, No. 1, 2009

A Novel Generic Session Based Bit Level Encryption Technique to Enhance Information Security

Manas Paul,1 Tanmay Bhattacharya,2
1Sr. Lecturer, Department of Computer Application, JIS College of Engineering, Kalyani, West Bengal e-mail:manaspaul@rediffmail.com 2Sr. Lecturer, Department of Information Technology, JIS College of Engineering, Kalyani, West Bengal e-mail: tanmay_bhattacharya@yahoo.co.in

Suvajit Pal,3 Ranit Saha4
3Student, Department of Information Technology, JIS College of Engineering, Kalyani, West Bengal e-mail:suvajitpal@gmail.com 4 Student, Department of Information Technology, JIS College of Engineering, Kalyani, West Bengal e-mail:ranit.saha@gmail.com

Abstract - In this paper a session based symmetric key encryption system has been proposed and is termed as Permutated Cipher Technique (PCT). This technique is more fast, suitable and secure for larger files. In this technique the input file is broken down into blocks of various sizes (of 2^n order) and encrypted by shifting the position of each bit by a certain value for a certain number of times. A key is generated randomly wherein the length of each block is determined. Each block length generates a unique value of “number of bits to be skipped”. This value determines the new position of the bits within the block that are to be shifted. After the shifting and inverting each block is XOR’ed with SHA-512 digest of the key. The resultant blocks from the cipher text. The key is generated according to the binary value of the input file size. Decryption is done following the same process as the technique is symmetric.

Keywords- Permutated Cipher Technique (PCT); Session Based; Number of Bits to Skip (NBSk); Maximum Iterations (MaxIter); Iterations done for encrypting (eIter); Iterations done for decrypting (dIter); Symmetric Key.

I. INTRODUCTION

In the age of science and technology everybody is using internet in almost every discipline of their daily life. Internet has made our communication faster and easier. Hence, maintaining the security of essential information is of utmost importance. Therefore many researchers are working in the field of encrypting the data transacted through internet. Encryption process converts the transacted data into cipher text which is otherwise illegible without the proper decrypting technique. Many algorithms based on various mathematical models are available, but each of them has their own share of merits and demerits. No single algorithm is perfect. As a result, continual researches are being made in the field of cryptography to enhance the security even further.

In this paper a new technique has been proposed, where the source message is considered as a stream of binary bits whose positions are shifted [1] to create the encrypted message. The key is generated in a unique random manner [2, 3] (cryptographically strong pseudo-random number generator RFC 1750) and all the variables involved are calculated on the

basis of the random generated sequence of the numbers within the key. Section II of the paper discusses about the proposed scheme with block diagrams. Section III discussed about the key generation, the encryption and decryption procedure, section IV shows the results on different files and comparison of the proposed technique with TDES [4] and AES [5], section V & VI deals with conclusions & future scope respectively.

II. THE SCHEME

The PCT algorithm consists of three major divisions: • Key Generation • Encryption Mechanism • Decryption Mechanism

Key Generation:

Encryption Mechanism:

Decryption Mechanism: Input File Key (K) Encrypted File Input File Key Generator Key (K) (IJCSIS) International Journal of Computer Science and Information Security,
Vol. 3, No. 1, 2009

III. PROPOSED ALGORITHM

Key Generation Algorithm:

1. Total length of the input file is calculated and the corresponding binary representation of the above value is stored in an array.
2. Two index values of the array (mH, mL) are selected randomly.
3. The value of the content of mH cell be decreased by a certain number “x” and “x” is multiplied to 2(mH-mL) and added to the contents of mL cell. The steps are repeated for random number of times.
4. The index values are written into another array, repeating them the number of times of their cell value.
5. The contents of this new array are swapped for random number of times.

Encryption Algorithm:

1. A block size is read from key. If block size is sufficed from available byte input stream then proceed, else required padding be added to achieve block size.

2. Odd bits are flipped.

3. Now Consider bits only in even positions, let i de

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