Abstract: A steganographic message/advertisement embedding method is presented that can be used for contextual and targeted advertising supporting unobtrusive and on-demand message/advertisement delivery. The present invention presents over two client devices, the method includes receiving, on a first client device, a primary multimedia presentation with a plurality of steganographic codes embedded therein; whereby the steganographic code is not perceivable during a rendering of the multimedia presentation and the steganographic code is associated with at least one secondary multimedia presentation. Next; the primary multimedia presentation is rendered on the first client device. The first client device receives a user selection to select at least one of the steganographic codes.

Abstract: Methods and apparatus are provided for the efficient use of cognitive radios in the performance of dynamic spectrum access. This includes spectrum sensing algorithms, adaptive optimized sensing of parameters based on changing radio environments, and identifying vacant channels. Protocols for switching communication links to different channels, and synchronizing communicating nodes in order to maintain reliable connectively while maximizing spectrum usage are also provided.

Abstract: A method is disclosed for modifying an iterated block cipher by controlling the operations and transformations that cause diffusion. In one embodiment which is applicable to any iterated block cipher (12), a diffusion function (10), during encryption, is selected based on a parameter which measures the order of permutation of the diffusion function (10) and applies the diffusion function (10) to the encryption routine (12). The user chooses the required amount of diffusion for a given block of plaintext (11). The plaintext (11) is then encrypted using the modified diffusion function (10) to produce a ciphertext (14) which is then sent over a communications channel (16) which may be noisy. At the receiving end (18) of the communications channel (16), the received ciphertext (20), which now may be corrupted by bit errors, is passed through an iterated block cipher decryption routine (22) using the same diffusion function (10) selected earlier during encryption.