Asoke Nath

Work place: Department of Computer Science, St. Xavier’s College [Autonomous], Kolkata, India



Research Interests: Information Security, Network Security, Information-Theoretic Security


Asoke Nath is the Assistant Professor at St. Xavier‟s College(Autonomous), Kolkata. He is involved in research work in the area of symmetric key cryptography, asymmetric key cryptography, Steganography, Green Computing, e-learning methodlogies, Distance education methodlogies. He has published many research papers from International Conferences and Journals. He has given invited tutorial on Introduction to Cryptography and Network security in National and International conferences.

Author Articles
Ultra Encryption Standard Modified (UES) Version-I: Symmetric Key Cryptosystem With Multiple Encryption and Randomized Vernam Key Using Generalized Modified Vernam Cipher Method, Permutation Method, and Columnar Transposition Method

By Satyaki Roy Navajit Maitra Shalabh Agarwal Joyshree Nath Asoke Nath

DOI:, Pub. Date: 8 Jul. 2012

In the present paper a new combined cryptographic method called Modified UES Version-I has been introduced. Nath et al. have already developed several symmetric key methods. It combines three different methods namely, Generalized Modified Vernam Cipher method, Permutation method and Columnar Transposition method. Nath et al recently developed few efficient combined encryption methods such as TTJSA, DJMNA where they have used generalized MSA method, NJJSAA method and DJSA methods. Each of the methods can be applied independently to encrypt any message. Nath et. al showed that TTJSA and DJMNA is most suitable methods to encrypt password or any small message. The name of this method is Ultra Encryption Standard modified (UES) version-I since it is based on UES version-I developed by Roy et. al. In this method an encryption key pad in Vernam Cipher Method also the feedback has been used which is considered to make the encryption process stronger. Modified UES Version-I may be applied to encrypt data in any office, corporate sectors etc. The method is most suitable to encrypt any type of file such as text, audio, video, image and databases etc.

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Ultra Encryption Standard (UES) Version-III: Advanced Symmetric Key Cryptosystem With Bit-level Encryption Algorithm

By Satyaki Roy Navajit Maitra Shalabh Agarwal Joyshree Nath Asoke Nath

DOI:, Pub. Date: 8 Jul. 2012

In the present paper a new cryptographic method called UES Version-III has been introduced. Nath et al recently developed few efficient encryption methods such as UES version-I, Modified UES-I, UES version-II, TTJSA, DJMNA Nath et. al showed that TTJSA and DJMNA is most suitable methods to encrypt password or any small message. The name of the present method is Ultra Encryption Standard Version-III. It is a Symmetric key Cryptosystem which includes multiple encryption, bit-wise randomization, new advanced bit-wise encryption technique with feedback. In this paper, the authors have performed encryption entirely at the bit-level to achieve greater strength of encryption. In the result section the authors have shown the spectral analysis of encrypted text as well as plain text. The spectral analysis shows that UES-III is free from standard cryptography attack such as brute force attack, known plain text attack and differential attack.

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Advanced Steganography Algorithm Using Randomized Intermediate QR Host Embedded With Any Encrypted Secret Message: ASA_QR Algorithm

By Somdip Dey Kalyan Mondal Joyshree Nath Asoke Nath

DOI:, Pub. Date: 8 Jun. 2012

Due to tremendous growth in communication technology, now it is a real problem / challenge to send some confidential data / information through communication network. For this reason, Nath et al. developed several information security systems, combining cryptography and steganography together, and the present method, ASA_QR, is also one of them. In the present paper, the authors present a new steganography algorithm to hide any small encrypted secret message inside QR CodeTM , which is then randomized and then, finally embed that randomized QR Code inside some common image. Quick Response Codes (or QR Codes) are a type of two-dimensional matrix barcodes used for encoding information. It has become very popular recently for its high storage capacity. The present method is ASA_QR is a combination of strong encryption algorithm and data hiding in two stages to make the entire process extremely hard to break. Here, the secret message is encrypted first and hide it in a QR CodeTM and then again that QR CodeTM is embed in a cover file (picture file) in random manner, using the standard method of steganography. In this way the data, which is secured, is almost impossible to be retrieved without knowing the cryptography key, steganography password and the exact unhide method. For encrypting data The authors used a method developed by Nath et al i.e. TTJSA, which is based on generalized modified Vernam Cipher, MSA and NJJSA method; and from the cryptanalysis it is seen that TTJSA is free from any standard cryptographic attacks, like differential attack, plain-text attack or any brute force attack. After encrypting the data using TTJSA,the authors have used standard steganographic method To hide data inside some host file. The present method may be used for sharing secret key, password, digital signature etc.

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An Integrated Symmetric Key Cryptographic Method – Amalgamation of TTJSA Algorithm , Advanced Caesar Cipher Algorithm, Bit Rotation and Reversal Method: SJA Algorithm

By Somdip Dey Joyshree Nath Asoke Nath

DOI:, Pub. Date: 8 May 2012

In this paper the authors present a new integrated symmetric-key cryptographic method, named SJA, which is the combination of advanced Caesar Cipher method, TTJSA method, Bit wise Rotation and Reversal method. The encryption method consists of three basic steps: 1) Encryption Technique using Advanced Caesar Cipher, 2) Encryption Technique using TTJSA Algorithm, and 3) Encryption Technique using Bit wise Rotation and Reversal. TTJSA Algorithm, used in this method, is again a combination of generalized modified Vernam Cipher method, MSA method and NJJSAA method. Nath et al. already developed some symmetric key encryption methods namely MSA, DJSA, DJJSA, modified DJJSA, NJJSA, TTJSA, TTSJA, DJMNA, UES-I, UES-II etc. The cryptanalysis shows that TTJSA is free from standard cryptographic attacks such as differential attack, plain text attack or any brute force attack. In the present method the authors have used advanced modified Caesar Cipher method where the authors have modified the standard Caesar Cipher method and then they applied TTJSA method to make the entire crypto system very hard to break. The present method has been tested on different plain text specially with repeated character and the spectral analysis of the plain text and the encrypted is also been shown. The spectral analysis shows that the present cryptography method, SJA can not be broken with any kind of standard cryptography attack. The authors propose that the present method will be most suitable for password, SMS or any kind of small message encryption.

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