A New Hybrid Technique for Data Encryption - IEEE Xplore Digital ...

Proceedings of 2015 Global Conference on Communication Technologies(GCCT 2015)

A New Hybrid Technique for Data Encryption Md.Atiullah Khan1, Kailash Kr.Mishra1, N.Santhi2, J.Jayakumari2 1

Student IEEE Member, Department of ECE, Noorul Islam University, Kumaracoil, Tamil Nadu, India

2

Department of Electronics and Communication Engineering, Noorul Islam University, Kumaracoil, Tamil Nadu, India

Abstract: Data encryption has been widely applied in many data processing areas. Various encryption algorithms have been developed for processing text documents, images, video, etc. If we are able to collaborate the advantages of the different existing encryption methods, then a new hybrid encryption method can be developed which offers better security and protection. So, in order to accomplish the Hybrid encryption technique, data encryption techniques using Fibonacci series, XOR logic, PN sequence are studied, analyzed and their performance is compared in this paper. The message is divided into three parts and these three different techniques are applied to these parts and the performance is again analyzed. The application of these three different methods to different parts of the same message along with two keys, namely, segmenting key and encrypting key to provide further authentication and validation is the basis of our paper.

Keywords: Encryption, Decryption, Fibonacci series, XOR Cipher, PN Sequence, Hybrid Technique

I. INTRODUCTION A secure computing environment would not be complete without consideration of encryption technology. The term encryption refers to the practice of obscuring the meaning of a piece of information by encoding it in such a way that it can only be decoded, read and understood by people for whom the information is intended. The use of simple codes to protect information can be traced back to the fifth century BC. As time has progressed, the methods by which information is protected have become more complex and more secure. Encryption is a method of transforming data with the intension of keeping it a secret. It uses an algorithm called a cipher to encrypt data and it can be decrypted only using a special key. Encrypted information is known as cipher text and the process of obtaining the original information (plaintext) from the cipher text is known as decryption. Encryption is specially required when communicating over an

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untrusted medium such as internet, where information needs to be protected from other third parties. Modern encryption methods focus on developing encryption algorithms (ciphers) that are hard to break by an adversary due to the computational hardness (therefore could not be broken by a practical means). Two of the widely used encryption methods are Symmetric key encryption and Public-key encryption. In Symmetric key encryption, both the sender and the receiver share the same key used to encrypt the data. In Public-key encryption, two different but mathematically related keys are used. Even though both encoding and encryption are methods that transform data in to a different formats, the goals tried to achieve by them are different. Encoding is done with the intension of increasing the usability of data in different systems and to reduce the space required for storage, while encryption is done to keep the data secret from third parties. Encoding is done using publicly available methods and it can be easily reversed. But encrypted data cannot be decrypted easily. It requires the possession of special piece of information called a key. II. LITERATURE REVIEW In the recent past, ASCII values of input data have been used to encrypt the data in symmetric key encryption algorithms [1]. Also work has been carried on in the field of PN Sequence generation using bit wise operators available in C which significantly reduces the energy consumption in communication [2]. New algorithms that provide data encryption at multiple levels and security against crypto analysis which reduces computational overhead have been discussed [3]. Techniques wherein the plaintext is converted into cipher text using Fibonacci number generated and hence the conversion of the cipher text to Unicode symbols to provide security from third party have been tried upon [4]. The FFT Technique has been used for text file encryption by making use of

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scrambling pattern [5]. In the past methods where encryption of data in blocks using operations like rotation and logical XOR along with the usage of a one-time sub key derived from session key of that particular block which is further obtained from the master key has been accomplished [6]. Also, multiple encryption has been employed in Secure Electronic Transaction to provide data confidentiality and prevent unauthorized access to any part of information over wireless networks as internet [7]. In the last few years efforts have been made to protect digital data from tampering by using a combination of cryptography and stenography [8]. And robust transmission of unbounded strings using Fibonacci representations have been performed in the past [9]. III. PROPOSED WORK Encryption is said to occur when data is passed through a series of mathematical operations that generate an alternate form of that data, the sequence of these operations is called an algorithm. To help distinguish between the two forms of data, the unencrypted data is referred to as the plaintext and the encrypted data as cipher text. The security of encryption lies in the ability of an algorithm to generate cipher text that is not easily reverted to the original plaintext. As we have seen that the simple existing encryption methods are very easy to decrypt once the key or logic is known to the unauthorized person, so in order to enhance the security of the data we are going for a combination of different encryption methods to form a hybrid technique of encryption. We have chosen the following simple encryption techniques: a. b. c.

Fibonacci Series XOR Cipher PN Sequence

Each technique is unique and has its own specific advantages and disadvantages. A. HYBRID TECHNIQUE We propose to combine the above mentioned three different methods to encrypt different parts of the same data which enhances security by making decryption extremely difficult for any third party which tries to access our data without proper authorization. For example if we take the input to be “This is our plaintext”, it has 21 characters which is easily

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divisible by 3. The hybrid technique thus divides this message into three parts and encrypts them with the three different techniques as shown in Figure 1. This is our plaintext

This is

XOR CIPHER

our pl

FIBONACCI SERIES

aintext

PN SEQUENCE

Figure 1: Diagrammatic Representation of Data Splitting using Segmenting key In this technique of ours we have combined the above three mentioned techniques to encrypt the given data. The input data is divided into segments of equal length by a numeric value as entered by the sender. So, if the length of the input message is 21 characters long and the sender enters the segmenting key value as 7 then the first 7 characters are encrypted using Fibonacci Series. The next 7 characters are encrypted using XOR Cipher and the remaining 7 characters are encrypted using PN Sequence. Figure 2 shows the block diagram of the Hybrid Technique. While the segmenting key is used to divide the data into segments another key is used for encrypting the input data. With the help of this key only the plain text is converted into cipher text. And again the same key is used to decrypt the cipher text at the receiver. So, this unique key should be known both to the sender and receiver of the data. Also, both the sender and receiver of data must know the value of segmenting key for proper encryption and decryption. So, if the receiver enters the wrong value of the segmenting key then all the data will not be decrypted and hence some data will be lost. Similarly, if the sender enters a value of the segmenting key which does not exactly divides the total character length of the input message then again the entire message will not be encrypted and some data will be lost. So, only when both the segmenting key value and the encrypting key values are known to the authorized users then only can the data be properly encrypted and decrypted. By this technique, a two-step verification is provided so that the data is secure and any authorized access can be avoided. So, only when an individual has both the values for the segmenting key and the encrypting key then

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only can the data be decrypted. Also, since three different techniques are used simultaneously for encrypting different parts of the same data so decryption by unauthorized individuals becomes difficult since multiple key values are used.

encrypted by applying the bitwise XOR operator to every character using a given key as depicted in Figure 3. To decrypt the output, merely reapplying the XOR function with the key will remove the cipher. Load the input data

Input Message Select the repeating key Message Splitting Perform XOR operation between input data and repeating key Encryption Technique 1

Decryption Technique 1

Encryption Technique 2


Encryption Technique 3


Process of Combining Decoded Message

Original Message

Figure 2: Block Diagram of Hybrid Technique The three encryption techniques used in the Hybrid technique are discussed below. B. XOR CIPHER In cryptography, the simple XOR cipher is a type of additive cipher, an encryption algorithm that operates according to the principles: A ⊕ 0 = A, A ⊕ A = 0, (A ⊕ B) ⊕ C = A ⊕ (B ⊕ C), (B ⊕ A) ⊕ A = B ⊕ 0 = B, where ⊕ denotes the exclusive disjunction (XOR) operation. With this logic, a string of text can be

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Figure 3: Flowchart of XOR Cipher Method

Find the largest Fibonacci number equal to or less than N

Subtract that number from N, keeping track of the remainder.

If the number subtracted was the ith Fibonacci number F(i), put a 1 in place i−2 in the code word (counting the left most digit as place 0).

Repeat the previous steps, substituting the remainder for N, until a remainder of 0 is reached.

Place an additional 1 after the rightmost digit in the code word.

Figure 4: Flowchart of Fibonacci Series Method

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C. FIBONACCI SERIES The Fibonacci numbers or Fibonacci sequence are the numbers in the following integer sequence 1 1 2 3 5 8 13 21 34 55 89 144 … or 0 1 1 2 3 5 8 13 21 34 55 89 144 … We generally use the above two sequences for mathematical operations. The sequence can be varied by adding the first three or four numbers of the sequence to form the next number. Thus a large number of such series can be generated by simply applying different additive logics. Figure 4 shows the execution of the Fibonacci Series Method.

These methods combine together to form the Hybrid Technique. The following section discusses the results obtained after analysis. IV. ANALYSIS A 21 character input message when encrypted using Fibonacci Series Method produces a 42 character encrypted data. The XOR Cipher method and PN Sequence method produce the same number of characters in the encrypted data as in the original input message. The Hybrid Technique produces 28 characters in the encrypted data which is considerably less than the Fibonacci Series Method as shown in Figure 6.

In cryptography, pseudo random noise is a signal similar to noise and it seems to lack any definite pattern. Pseudo random noise consists of a deterministic sequence of pulses that will repeat itself after its period. In cryptographic devices, the pseudo random noise pattern is determined by a key and the repetition period can be very long, even millions of digits. Its execution is shown in Figure 5.

Encrypted Bits

D. PN SEQUENCE

45 40 35 30 25 20 15 10 5 0

7

42 21

21

14 7

XOR Cipher

Fibonacci PN Hybrid Series Sqeuence Technique

Methods Initial states

Required no of output bits

Input

Spreader

Encrypted signal

Figure 5: Flowchart of PN Sequence Method

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FS bits

PN bits

Figure 6: Number of encrypted bits in the different methods

PN sequence generator

PN sequence

XOR bits

The segmenting key is such chosen so that it divides the message into three equal parts. The three methods are independent of the segmenting key concept. In the Hybrid Technique if the input message is divided using an improper segmenting key, then encryption of the entire input message does not take place. So during the decryption only the part of the message which is encrypted will be displayed, rest of the data is lost, thereby, protecting unauthorized access. When a 243 character input message is being encrypted with one key and decrypted with another key then the following observations are made. The Fibonacci series method is independent of the key and thus the whole message is correctly decrypted. The other two methods do not show any part of the input message at the decrypted output. In the Hybrid technique, only the part of the message which is

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encrypted using Fibonacci series method is displayed and the remaining part of the message is corrupted. The dark area in the pie chart shows the part of the message which is displayed as shown in Figure 7.

[2] Rina Choudhary, “An enhancement of code and energy optimization in PN Sequence generation”, in International Journal of Engineering and Management Sciences, I.J.E.M.S., VOL.4 (4) 2013: 426-429, ISSN 2229-600X

[3] Sharad Kumar Verma and D.B. Ojha , “An application

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of data encryption technique using random number generator”, in International Journal of Research Studies in Computing, Volume 1, Number 1, 35-42, April 2012

[4] A. Joseph Raphael and V. Sundaram , “Secured Communication through Fibonacci Numbers and Unicode Symbols”, in International Journal of Scientific & Engineering Research, Volume 3, Issue 4, April-2012, ISSN 2229-5518

[5] Sudha Rani, T. C. Sarma and K. Satya, “Text File

81 XOR Cipher

Fibonacci Series

PN Sequence

Figure 7: Decryption using improper encrypting key V. CONCLUSION Input messages of variable length were encrypted using the four techniques and the following observations were made. The Fibonacci series method leads to more number of bits during encryption than the original text. In the XOR CIPHER method, if the key is known once, the data can be easily decrypted. The PN sequence increases the storage requirement of the system and is complex. In the Hybrid Technique, the number of encrypted bits is lesser than that of Fibonacci method. The segmenting key here provides more security to the transmitted message by decrypting the original message at the receiver only when the segmenting key at both sides are equal, otherwise loss of data occurs if the message is not completely encrypted. Also the symmetric key provides authentication and validation. Also the MATLAB code used is very simple and memory efficient.

Encryption Using FFT Technique In Lab View 8.6”, in IJRET: International Journal of Research in Engineering and Technology ISSN: 2319-1163, Volume: 01, Issue 01, Sep2012

[6] D. Sravan Kumar, CH. Suneetha and A.Chandrasekhar, “A Block Cipher Using Rotation and Logical XOR Operations”, in IJCSI International Journal of Computer Science Issues, Vol. 8, Issue 6, No 1, November 2011, ISSN (Online): 1694-0814

[7] Himanshu Gupta and Vinod Kumar Sharma, “Role of multiple encryption in secure electronic transaction”, in International Journal of Network Security & Its Applications (IJNSA), Vol.3, No.6, November 2011

[8] V. Sundaram and A. Joseph Raphael, “Secured CryptoStegano Communication Through Unicode”, in World of Computer Science and Information Technology Journal (WCSIT) ISSN: 2221-0741 Vol. 1, No. 4,138-143, 2011

[9] Alberto Apostolico and Aviezri S. Fraenkel, “Robust Transmission of Unbounded Strings Using Fibonacci Representations”, in Report Number : 85-545, 1985

Although this method provides more safety and security, the system becomes complex due to involvement of three different types of encoders thereby increasing the cost and complexity in its hardware implementation. VI. REFERENCES [1] Udepal Singh and Upasna Garg, “An ASCII value based text data encryption System”, in International Journal of Scientific and Research Publications, Volume 3, Issue 11, November 2013, ISSN 2250-3153

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