||Music industry suffered from an annual loss of five billion dollars due to illegal distributions of MP3s. Peer-to-Peer applications like Napster, KaZaA and Morpheus allow digital contents to be distributed freely over the Internet with ease. Hence, there is an urging need of a mechanism to protect the copyrights of digital contents. Digital Rights Management Systems (DRMS) have been used to address these problems. These systems generally deploy digital watermarking techniques to enforce copyrights management. Memon and Wong  proposed a buyer-seller watermarking protocol that only requires buyers to release an encrypted copy of their watermarks to sellers. The protocol can still identify the original buyers of unauthorized copies. However, we found that their protocol might not work in a second hand market. In this thesis, we will revisit this issue and give an adapted protocol called buyer-reseller watermarking protocol. We will also discuss the integration of our protocol to the NetBill micropayment system and e-Business XML (ebXML) .