Appendix A Definition of Terms Artifact: Artifacts are the irregularities that may be present in an image after processing. They are not related to the details of the image and sometimes accompany transmitted signals. Bit-plane: The bit-plane of an image is a set of bits corresponding to a given bit position in each of the binary numbers representing the image. Carrier: Carriers are the digital media that are used as a medium to carry the secret data. It is the medium into which the secret data is hidden. Ciphertext: It is the translated text which is formed by encrypting the secret data. It is the unordered or substituted text created by changing its readability and meaning. Coefficient: Coefficients are formed when a signal is transformed a from an image representation into a frequency representation by using discrete transformation. Cover-image: The image which is taken as a medium of covering the secret data. It is the original image into which the secret data is inserted into its redundant bits. Cryptanalysis: It is the study of attacks on the cryptography to find weaknesses in them, without necessarily knowing the key or the algorithm. Decibel: The decibel (db) is a logarithmic unit used to express the ratio between two values of a physical quantity. It is used to measure signal level after processing and is widely used in electronics, signals and communication. Decryption: Decryption is the process of taking encoded or encrypted text and converting it back into original plaintext which are understandable. Eavesdropper: Eavesdroppers are the attackers (unauthorized person) who try to break a signal through communication channel to check if the signal contains any secret data. 183
Appendix A Encryption: The process of transformation from plaintext (secret message) to ciphertext (unreadable format) to create a data that is not understandable. Entropy coding: Entropy coding encodes an image by rounding the coefficient values to integer to reduce the size. Entropy coding is lossless compression. Fidelity: Fidelity is the perceptual similarity between images before and after processing. Keystream generator: It generates random sequence of numbers by partitioning the stego-key into random sequences. These sequences allocate positions of the secret bits. MSE: Mean squared error (MSE) shows variation between the cover- image and resultant (stego) image. A high quality image should have less MSE value. Payload: In steganography, payload relates to the amount of secret data that can be hidden into digital media. Pixel indices: Pixel indices are the random locations of the pixels which are formed using random number generator. Plaintext: It is the original secret message that is transformed into unordered state using encryption process. PRNG: The pseudorandom number generator (PRNG) generates sequence of random numbers using a stego-key which is used to select random pixels of the coverimage for hiding the secret data. The key is used as seed for the random number generation. PSNR: The Peak-Signal-to-Noise Ratio (PSNR) is the performance measurement criteria that show the relationship between the bit- or detection-error of two similar signals. A high quality image should have higher PSNR value. Randomization: It is the process of scattering the secret bits in different pixel position of the cover-image that makes the secret data to be in random order. Seed: The seed defines the starting point of a random number generator. It initiates the process of random number generation. 184
Appendix A Steganalysis: Steganalysis is the technique to detect whether a given digital media contains hidden data. The steganalysis plays a role in the selection of features or properties of the digital media to test for suspicious data. Steganalyst: Steganalyst is the individual (attacker) who performs the steganalysis with the purpose of detecting suspicious or secret data into a medium when transmitted. Stego-image: The resultant image formed as a result of the steganography algorithm which contains secret data embedded into it. Stego-key: The secret key used in the steganographic method to choose the random pixel position in the image. The security of a stego-key Target character: It is the last character that is embedded into the cover-image. The target character terminates the embedding and extraction process. Zigzag: Zigzag order is performed to group similar frequencies together by sorting the coefficients in zigzag ordering. 185
Appendix B List of Publications Journals 1. Laskar, S.A. and Hemachandran, K. (2012). An Analysis of Steganography and Steganalysis Techniques, Assam University Journal of Science and Technology, ISSN: 0975-2773, Vol. 9, No. 2, pp. 88-103. 2. Laskar, S.A. and Hemachandran, K. (2012). High Capacity data hiding using LSB Steganography and Encryption. International Journal of Database Management Systems (IJDMS), ISSN: 0975-5705, Vol. 4, No. 6, pp. 57-68. 3. Laskar, S.A. and Hemachandran, K. (2013). Steganography Based on Random Pixel Selection for Efficient Data Hiding. International journal of Computer Engineering and Technology (IJCET), ISSN: 0976-6367, Vol. 4, Issue 2, pp. 31-44. 4. Laskar, S.A. and Hemachandran, K. (2014). A Review on Image Steganalysis techniques for attacking Steganography, International Journal of Engineering Research & Technology (IJERT), ISSN: 2278-0181, Vol. 3, Issue 1, pp. 3400-3410. Book Chapters 1. Laskar, S.A. and Hemachandran, K. Combining JPEG Steganography and Substitution Encryption for Secure Data Communication. In David C. Wyld, et al. (Eds). Computer Science & Information Technology (CS & IT): ISSN: 2231-5403, CCSEA, SEA, CLOUD, DKMP, CS & IT 05, pp. 149 160, (2012). 186
Appendix B Conference and Symposium 1. Laskar, S.A. and Hemachandran, K. Combining JPEG Steganography and Substitution Encryption for Secure Data Communication has been presented in Second International Conference on Computer Science, Engineering and Applications (CCSEA)-2012, CCSEA, SEA, CLOUD, DKMP, CS & IT 5, Organized by AIRCC, May, 26-27, 2012, Delhi, India. Citation Count - (a) Laskar, S.A. and Hemachandran, K. (2012). An Analysis of Steganography and Steganalysis Techniques, Assam University Journal of Science and Technology, ISSN: 0975-2773, Vol.9, No-2, pp. 88-103. Cited by 1 Cited by 1. Maan, V. K. and Dhaliwal, H. S. (2013). Vector Quantization in Image Steganography. International Journal of Engineering Research & Technology (IJERT) Vol. 2, No. 4 (2013), pp. 421-424. (b) Laskar, S.A. and Hemachandran, K. (2012). High Capacity data hiding using LSB Steganography and Encryption." International Journal of Database Management Systems (IJDMS), ISSN: 0975-5705, Vol.4, No. 6, pp. 57-68., DOI: 10.5121/ijdms.2012.4605. Cited by 5 Cited by 1. Bansal, T. and Lamba, R. (2013). Steganography on Colour Images using 32x32 Quantization Table. International Journal for Advance Research in Engineering and Technology (IJARET), Volume 1, Issue V, 2013, pp. 68-72, ISSN: 2320 6802. 2. Vasudev, P. and Saurabh, K. (2013). Video Steganography Based on Improved DCT 32*32 Vector Quantization Method. International Journal of Software & Hardware Research in Engineering (IJSHRE), ISSN: 2347-4890, Vol. 1, No. 4, 2013, pp. 46-51. 187
Appendix B 3. Garg, T. and Vatta, S. (2014). A Review on Data Compression using Steganography. International Journal of Computer Science and Mobile Computing (IJCSMC), Vol.3 Issue.6, June- 2014, pg. 275-278, ISSN 2320 088X. (c) Laskar, S.A. and Hemachandran, K. (2013). Steganography Based On Random Pixel Selection for Efficient Data Hiding, International journal of Computer Engineering and Technology (IJCET), ISSN 0976-6367, Vol. 4, Issue 2, pp. 31-44. Cited by 4 Cited by 1. Qasim, M. A. and Pawar, D. (2013). Encryption & Steganography in IPv6 source address International Journal of Computer Engineering & Technology (IJCET), ISSN: 0976 6375, Vol.4, No. 2 (2013) pp. 315-324. 2. Sumathi, C. P.; Santanam, T. and Umamaheswari, G. (2013). A Study of Various Steganographic Techniques Used for Information Hiding." International Journal of Computer Science & Engineering Survey (IJCSES), ISSN: 0976-2760, Vol.4, no. 6 (2013), pp. 9-25. 3. Abdulhameed, Z. N. and Mahmood, M. K. (2014). High Capacity Steganography Based on Chaos and Contourlet Transform for Hiding Multimedia Data. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN: 0976-6472, Volume 5, Issue 1, (2014), pp. 26-42. 4. Mala, R. and Manimozi, I. A Novel Approach for Reversible Data Hiding in Encrypted Images Using Key Based Pixel Selection. International Journal of Computer Science & Engineering Technology (IJCSET), ISSN: 2229-3345, Vol. 5 No. 06 Jun 2014, pp. 715-719. 188
Appendix C Participation in Conferences and Workshops 1. National conference on Current Trends in computer Science (CTCS 2010), Department of Computer Science, Assam University, Silchar 22-24, February 2010, AUS. 2. ISI-AU Workshop On Intelligent Data Analysis: Theory and Application, 1-5, March 2011, Computer Vision and Pattern Recognition Unit, Indian Statistucal Institute, Kolkata and Department of Information Technology, Assam University, Silchar, India. 3. ISI-NEHU Winter School on Soft Computing, Pattern Recognition and Image Processing, October 20 24, 2011, Department of Information Technology, North- Eastern Hill University, Shillong, Meghalaya. 4. Workshop on Application of Mathematics in Computer Science and Engineering, August 2-4, 2011, Department of Mathematics, NIT, Silchar, India. 5. International Conference on Computer Science, Engineering and Applications, Organized by AIRCC, May, 26-27, 2012, New Delhi, India. 6. 13 th Workshop on Computational Information Processing, December 3-7, 2012, Electronics and Communication Sciences Unit, ISI Kolkata and Department of Information Technology, Assam University, Silchar, India. 7. Workshop on Role of IPR in Electronics, Communication, Computing and Devices, November 27-28, 2013, Tezpur University IPR Cell and Institute of Engineers, Silchar, India. 189