A Novel Distributed Image Steganography Method Based on Block-DCT

Distributed Image Steganography (DIS) is a method of hiding secret information in multiple carrier images, making it more difficult to trace than conventional steganographic techniques, and requiring a collection of affected images for the retrieval of the secret data. In this paper we concentrate on performing DIS on grayscale images using Block-DCT (Discrete Cosine Transformation). Distributed Image Steganography using Block-DCT adds to the security of DIS by embedding the secret data in the Frequency Domain. This makes the carrier images more immune to various steganalysis attacks as the secret data is more evenly distributed amongst the pixels of the carrier images making it more difficult to determine its existence. We use parity check in order to compensate for round-off errors that are typically associated with DCT.