Internet is one of the most significant achievement in the age of information technology, which has shown a phenomenal growth

Digital Image Watermarking is a technique for inserting information into an image that can be later extracted for a variety of purpose including identification, ownership authentication, and copyright protections. The goal of this paper is to design a secure watermarking scheme in spatial domain to identify the true buyer and to protect the ownership copyright of digital still images. The scheme inserts a binary watermark in an original image that serves as a fingerprint for a specific buyer. Utilizing the one-way property of the hash function, it generates the unique buyer fingerprint. An image index concept has been used to split the image randomly into disjoint blocks. A threshold is defined for manipulation of pixel intensities of these blocks. The amount of manipulation in pixel intensities absolutely depends upon the buyer fingerprint. The recovery of the watermark not only identifies the buyer but also protects the owner’s copyright. The extracted buyer fingerprint identifies the buyer of the original image. The scheme has the ability to trace the buyer involved in forgery. The experimental results show that the watermark can be retrieved from the attacked watermarked image even if the opponent has the complete information of watermarking scheme. Index Terms – Buyer fingerprint, Cryptographic hash function, Digital Watermarking, Image key.