The secure verification is important for watermarking protocols. A malicious arbitrator is able to remove an original watermark from an unauthorized copy of the digital content as a result of a security breach in the phase of arbitration and resell multiple copies of it with impunity. We propose a novel buyer-seller watermarking protocol of secure verification. In this scheme, a seller permutes an original watermark provided by a trusted Watermarking Certification Authority (WCA) and embeds it into digital content in an encrypted domain. In case an unauthorized copy is found, the seller can recover the original watermark from the watermark extracted from the copy and sends it to an arbitrator. Without the knowledge of permutations applied by the seller, the arbitrator is unable to remove the permuted watermark from the digital content. Hence, verification is secured. As an additional advantage of the proposed protocol, arbitration can be conducted without the need for the cooperation of the WCA or the buyer.