Abstract: Digital image security is an important issue in internet and network application. Digital images are distributed in encrypted format and watermarking of these images for authentication and copyright protection. We need media authentication in encrypted domain to enhance security. So sometime necessary to watermarking in encrypted media for copyright management and authentication. In this paper we use block cipher called RC5 encryption algorithm to encrypt image which gives minimum correlation coefficient and maximum throughput among all block cipher. We use LSB method to watermark the image. In this method we embed watermark in encrypted image and extraction of watermark in decrypted domain.

Keywords: Encryption, watermarking, RC5 encryption algorithm, block cipher, LSB method.