This paper presents a new approach for the copyright protection of digital multimedia data. The system applies cryptographic protocols and a public key technique for different purposes, namely encoding/decoding a digital watermark generated by any spread spectrum technique and the secure transfer of watermarked data from the sender to the receiver in a commercial business process. The public key technique is applied for the construction of a one-way watermark embedding and verification function to identify and prove the uniqueness of the watermark. Our approach provides secure owner authentication data who has initiated the watermark process for a specific data set. Legal dispute resolution is supported for multiple watermarking of digital data without revealing the confidential keying information. Content protection for images is provided by ciphering/deciphering the data in the transform domain.