一个基于DCT压缩编码的多媒体认证系统

多媒体的认证是近年来随着Intetnet的发展而提出的一个新问题，与消息认证类型，多媒体认证用于确认多媒体数据的来源并检测是否被篡改，其虽可用传统的方法即密码学上的数字签名来实现，但数字签名用于多媒体认证有其局限性，脆弱水印为多媒体的认下提供了较好的解决方案，目前已经有了各种不同的脆弱水印算法，但这些算法都有它们各自的优缺点，在对Marvel等的方法（以下称其为MHB法）进行成功的攻击之后，通过对MHB的修正与扩展，给出了一种更安全的、能抵抗基于DCT的压缩的脆弱水印算，通过实验还证明了以像素值或其高位比特产生MAC的数字水印不能抵抗基于DCT的压缩。

A DCT-BASED MULTIMEDIA AUTHENTICATION SCHEME

Multimedia authentication is a problem posed to the world along with the development of Internet recently. Similar to message authentication, multimedia authentication is used to authenticate the source and to detect manipulation. This could be achieved by cryptographic digital signature. However, digital signature has some disadvantages to this end. Fragile watermark renders itself useful in this domain. There exist several fragile watermark schemes in the literature and all have their own cons and pros. After a successful analysis of the fragile watermark scheme presented by Marvel et al. , a new fragile watermark scheme robust to DCT-based compression is presented,which is an extension of and much safer than the one of Marvel et al. . Experiments show that a digital watermark scheme which use pixel values or significant bits of pixel values as input of MAC could not resist DCT-based compression.