ISSN: 2250-3005 - ijcer

International Journal Of Computational Engineering Research (ijceronline.com) Vol. 2 Issue. 8Source ofmessagesOpponentI jKi : M,L E1 K : E * iM,LiiM j M j*Precoder Steganocoder SteganocoderDetector ofmessagesE wContainers’features’registration unitB uM j*S jDecoder ofmessagesL uSourceof containersL uK i K i*I jRecipient ofmessagesSource of keysSource of keysFig. 2. Block diagram of steganographic systemEach message M j M = {M 1 , M 2 , …, M m } corresponds to the probability P(M j ). The probability distribution of arandom process is given by a cumulative distribution of probability distribution sets of random variables, i.e. the set ofprobabilities:PM P M1,PM2,...,PMm. (6)Source of containers generates a flow of empty containers L u from the set L = {L 1 , L 2 , …, L l }. Work of the source ofcontainers can also be described by some random process, the specific realization of wh ich is the container L u . In this case wedeal with random containers that can be attributed to the corresponding probabilities :PL P L1,PL2 ,...,PLl.Much more often, in practice, a different type of containers is used, the formation of which is impossible to describe bya random process. In this case, the source container works on a deterministic rule, asked or authorized (e.g., transmitting) side,or the opponent. In the first case, a so-called selected container, i.e. the container used is not formed by chance, but is chosenby the party responsible for some non-stochastic characteristics. In the second case, the source container is managed by theopponent, and the containers themselves are generated by an attacker and imposed the transmitting side by a deterministicrule. Thus, we have the so-called imposed-on container.In the simplest case, a lot of empty containers contain only one element, which is used by the transmitting side toembed message and secretly pass it through a communication channel.L u shaped container is processed by the containers’ features’ registration unit. The main function of the containers’features’ registration unit is the selection of attributes (features) B u of incoming container L u , which will be used forembedding the message to M j .A source of keys in steganographic system generates a flow of the set of keys К and/or К * . Each keyK i K = {K 1 , K 2 , …, K k } corresponds to some probability P(K i ), and each K * i K * = {K * 1 , K * 2 , …, K * k } corresponds to theprobability P(K * i ). Random key generation process is given by the sets of probabilities:Issn 2250-3005(online) December| 2012 Page 93