Perceptual cryptography of JPEG compressed images on the JFIF bit-stream domain

Whereas conventional cryptography is suitable for any kind of data, it does not allow for perceptual degradation of encrypted data in multimedia-compressed formats. We present the notion of perceptual cryptography applied to JPEG compressed images. We propose a backward compatible format-compliant JPEG/JFIF encryption scheme that allows for the graceful degradation via encryption of compressed images with both configurable zone of encryption and quality loss. Applications include encrypted image sampling and purchase by consumers using existing JPEG renderers via broadcasting, peer-to-peer network seeding or Web-based publishing. Existing image encryption schemes (Dang, P.P. and Chau, P.M, 2000; Lintian Qiao and Nahrstedt, K., 1998; Jui-Cheng Yen and Jiun-In Guo, 1999, 2000; Scharinger, J., 1998) do not address configurable graceful degradation and backward compatibility on the bit-stream domain at the same time.