In this chapter, a robust watermarking technique based on encryption in fractional wavelet Domain is presented to improve the protection and authentication of the images. The core idea of the proposed watermarking scheme is to encrypt an image via fractional wavelet transform and then watermark is embedded in encrypted image by modifying the singular values. After embedding, watermarked encrypted image is decrypted with the help fractional wavelet transform to get the watermarked image. First, watermarked image is encrypted by same algorithm at the receiver's end and then watermark is extracted by proposed watermark extraction algorithm. The feasibility of this method and its robustness against different kind of attacks are verified by computer simulations. © 2009 Springer-Verlag Berlin Heidelberg.