A New Perfect Hashing based Approach for Secure Stegnography Imran Sarwar Bajwa School of Computer Science University of Birmingham Birmingham, UK imran.sarwar@cs.bham.ac.uk Rubata Riasat Department of Computer Science & IT The Islamia University of Bahawalpur Bahawalpur, Pakistan rubata_riasat@yahoo.com Abstract—Image stegnography is an emerging field of research for secure data hiding for data transmission over internet, copyright protection, and ownership identification. A couple of techniques have been proposed for colour image stegnography. However, the colour images are more costly to transmit on internet due to their size. In this paper, we propose a new perfect hashing based approach for stegnography in grey-scale images. The proposed approach is more efficient and effective that provides a more secure way of data transmission at higher speed. The presented approach is implemented into a prototype tool coded in VB.NET. The presented approach is effective in a way that multiple file formats such as bmp, gif, jpeg, and tiff are also supported. A set of sample images were processed with the tool and the results of the initial experiments indicate the potential of the presented approach not only in terms of secure stegnography but also in terms of fast data transmission over internet. Keywords- Grey-scale Images; Stegnography; Hash-based algorithm; image, Perfect hashing I. INTRODUCTION Since the early days of computers, the data security is one of the premier issues of research. Image stegnography [1] is a modern way of hiding information in a way that the unwanted people may not access the information. Data used to hide data in stegnography can be text or image. In modern times, image stegnography can be helpful in a number of ways such as hiding the secret data [2], data authentication, ensuring authenticated data availability for academic usage, monitoring of data piracy, labelling electronic data/contents, copyright protection, ownership identification, providing confidentiality and integrity enhancement control of electronic data piracy etc. [3]. Following is overview of used techniques for image stegnography. A. Algorithms for Image Stegnography Since the term image stegnography has been coined in the research community, various approaches, algorithms and techniques have been presented. The major examples are Data Encryption Standard (DES) [2], International Data Encryption Algorithm (IDEA) [2], Secure Hash Algorithm (SHA) [4], [10], Advanced Encryption Standard (AES) [6], Chaos [8], Message Digest 5 (MD5) [7], and Bit Stream Ciphers (BSC) [11]. All these algorithms have their respective pros and cons. There are some algorithms those use hash functions to hide data in images. The examples of such algorithms are MD5 and SHA but these algorithms provide susceptible security [3], [4]. Some of these algorithms are good for small data such as AES, DES, and IDEA but their performance deteriorates if the size of the data increases [4], [5]. B. Contribution to Knowledge In this paper, we present a perfect hashing based approach for information hiding in the grey-scale images. The presented approach is based on a robust perfect hash-function algorithm. The experiments with the proposed algorithm indicate that the used algorithm is not only more secure but also more efficient in terms of processing cost. The proposed approach is more efficient and effective that provides a more secure way of data transmission at higher speed. The presented approach is implemented into a prototype tool coded in VB.NET. The presented approach is effective in a way that multiple file formats such as bmp, gif, jpeg, and tiff are also supported. The rest of the paper is structured as the section 2 presents the related work. The used hashing-based algorithm for data hiding is explained in section 3 and the proposed framework for grey-scale image stegnography is described in section 4. The tool support is section 5 succeeded by the implementation details. Section 6 presents the evaluation of the presented tool and finally the paper is concluded with the future work. II. RELATED WORK In last couple of decades, with the increase in use of internet for data communication, the need of secure data transmission and data hiding has been emerged into real challenge. Image stegnography is one of the premier solutions for secure data hiding [1]. Some of the algorithms such as International Data Encryption Algorithm (IDEA) [2], Advanced Encryption Standard (AES) [6], Data Encryption Standard (DES) [2], are good for little amount of data but not good for massive data sets as these algorithms involve intensive computation and required super fast processing machines [4], [5]. On the other hand, few algorithms such as Message Digest 5 (MD5) [7], Bit Stream Ciphers (BSC) [11], Secure Hash Algorithm (SHA)