Y. Hao et al. (Eds.): CIS 2005, Part II, LNAI 3802, pp. 589 – 596, 2005. © Springer-Verlag Berlin Heidelberg 2005 Alternatives for Multimedia Messaging System Steganography Konstantinos Papapanagiotou 1 , Emmanouel Kellinis 2 , Giannis F. Marias 1 , and Panagiotis Georgiadis 1 1 Dept. of Informatics and Telecommunications, University of Athens, Panepistimiopolis, Ilissia, Greece, GR15784 conpap@di.uoa.gr, marias@mm.di.uoa.gr, georgiad@di.uoa.gr 2 KPMG LLP, One Canada Square, London E14 5AG, United Kingdom emmanouel.kellinis@kpmg.co.uk Abstract. The Multimedia Messaging System allows a user of a mobile phone to send messages containing multimedia objects, such as images, audio or video clips. MMS has very quickly gained the popularity of SMS among mobile us- ers. Alongside, the need for a secure communication became more imperative. Hiding information, especially in images has been an attractive solution for se- cret communication. In this paper we examine the possibilities for the use of steganography within a multimedia message. The most widely known algo- rithms for steganography are presented and discussed. Their application in a mobile environment is analyzed and a theoretical evaluation is given. 1 Introduction One of the most popular uses of mobile phones has been the exchange of messages between users. The Short Messaging System (SMS) was introduced with GSM mo- bile phones and it very rapidly became popular among users. The Multimedia Mes- saging System (MMS) offers the ability to send and receive multimedia content using a mobile phone. Nowadays, most of the mobile phones not only are capable of send- ing and receiving Multimedia Messages (MM), but also contain an embedded camera and can run customized applications (e.g. using Java 2 Platform Micro Edition, J2ME). Most research regarding security in mobile environments with limited resources in terms of processing power, memory capacity and energy autonomy, is focused on the implementation of symmetric and asymmetric cryptographic algorithms. Steganogra- phy differs from cryptography in the sense that it tries to hide the message instead of transforming it so as to obscure its meaning [17]. In some cases, steganography may actually prove to be more effective. The combination of both may give the best re- sults, as a message can be encrypted before it is hidden into another object. Cryptog- raphy has received most attention until now, leaving a great space for research on steganography. Steganography concerns itself with ways of embedding a secret mes- sage into a cover object, without altering the properties of the cover object evidently. The embedding procedure is typically related with a key, usually called a stego-key. Without knowledge of this key it will be difficult for a third party to extract the