Digital rights management system and method for protecting digital content

A digital content management system operative in a distributed network includes a SDP server and a client. The SDP server includes a content issuer and a right issuer. The content issuer is configured to randomly generate a first key, convert the first key to a second key by a conversion function, and encrypt a portion of a digital content item with the second key to form an encrypted portion, wherein the encrypted portion has its corresponding character code. The right issuer is configured to generate a right object, which includes the first key, and encrypt the right object.