DOWNLOADABLE CONTENTS SECURITY SYSTEM AND DOWNLOADABLE CONTENTS SECURITY METHOD

A downloadable content security system and a security method thereof are provided to process data in bidirectional ways and manage a history of user download by receiving contents in an open manner without the dependence on a specific system. A PS(Personalization Sever) searches and downloads an original CAS, DRM, or ASD image registered at a file system, and creates a secret key for encrypting the downloaded image. The PS encrypts the image with the created secret key and performs an electronic signature to the encrypted image. The PS uploads the signed image to a download sever, and the secret key is encrypted to an SM public key and is transmitted to a DCAS host. Downloaded contents include two images among CAS, DRM and ASD images, and an integrated image for the downloaded contents is created. The integrated image is encrypted, an electronic signature is performed to the encrypted to the integrated image, and then the signed integrated image is uploaded to the download sever.