International Journal of Computers and Applications, Jul 13, 2011
The Global System for Mobile communication, GSM voice calls are encrypted using a family of algor... more The Global System for Mobile communication, GSM voice calls are encrypted using a family of algorithms collectively called A5. A5/1 is the stream cipher which encrypts the information transmitted from mobile user. Initially A5 algorithm was kept secret to ensure the security but as algorithm was disclosed many cryptanalytic attacks were proposed and proved the A5 algorithm cryptographically weak. In this paper, proposed enhanced A5/1 is described and it's analysis with different parameters is done. Enhanced A5/1 is proposed to make it robust and resistive to the attacks. Modification is done in two ways (1) feedback tapping mechanism which is enhanced by variable taps for LFSR (Linear Feedback Shift Register) and random shuffling of LFSRs, which increases the complexity of the algorithm without compromising the properties of randomness and (2) clocking rule. The modification has been proposed keeping the ease of implementation in mind. This modified algorithm has been simulated in MATLAB and tested its randomness properties by 'Randomness test suit' given by NIST-National Institute of Standard and Technology and obtained satisfactory results. Further analysis of A5/1 is done by varying it's parameters to achieve better results.
International Journal of Computer Applications, 2013
Security of data is very important in data communication. Everyday a lot of information is transf... more Security of data is very important in data communication. Everyday a lot of information is transferred form one user to another on internet and so the possibility of data theft also increases. Steganography provides a solution for the security of information during data transmission. Steganography is the science which makes the valuable information invisible to prevent it from unauthorized user. In this paper an audio message has been embedded in an image using the LSB (Least Significant Bit) technique and the wavelet transform. To hide a speech in an image is challenging as size of speech is larger than size of image. Number of bits in 1kb of speech is almost equal to an image. This paper describes how maximum speech can be embed in an image.
Abstract In recent years, image encryption has grown much to provide information security to end ... more Abstract In recent years, image encryption has grown much to provide information security to end user. There are various algorithms for encrypting the image. RC5 is a block cipher and can be used for image encryption. In this paper, weaknesses of RC5 for image encryption ...
Enhancement of A5/1: Using variable feedback polynomials of LFSR
The Global System for Mobile communication, GSM is the most widely used cellular system in the wo... more The Global System for Mobile communication, GSM is the most widely used cellular system in the world, with over a billion customers around the world. GSM was the first cellular system which seriously considered security threats. Previous cellular systems had practically no security, and they were increasingly the subject of criminal activity such as eavesdropping on cellular calls, phone cloning, and call theft. The GSM voice calls are encrypted using a family of algorithms collectively called A5. A5/1 is the stream cipher which encrypts the information transmitted from mobile user. Initially A5 algorithm was kept secret to ensure the security but as algorithm was disclosed many cryptanalytic attacks were proposed and proved the A5 algorithm cryptographically weak. In this paper the modification in A5/1 is proposed to make it robust and resistive to the attacks. Modification is done in two ways (1) feedback tapping mechanism which is enhanced by variable taps for LFSR (Linear Feedback Shift Register) and random shuffling of LFSRs, which increases the complexity of the algorithm without compromising the properties of randomness and (2) clocking rule. The modification has been proposed keeping the ease of implementation in mind. This modified algorithm has been simulated in MATLAB and tested its randomness properties by `Randomness test suit' given by NIST-National Institute of Standard and Technology and obtained satisfactory results.
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Papers by Nikesh Bajaj