SOFT IMAGE AUTHENTICATION • USING IM AC

Abstract

Soft image authentication codes tolerate errors in the message to some extent, but their underlying checksums are constructed such that tampering and forgery are easy to detect. These codes are probabilistic in nature and have the property that they change slowly as the Hamming distance between the original and modified data increases. When IMAC is applied to images it is possible to detect and locate tampering. Techniques such as block averaging, parallel approximate message authentication code (AMAC) computation and image histogram enhancement are used in the construction of the approximate IMAC. Controlled Permutations are used to improve the security of code. The performance of IMAC in two image modification scenarios, namely, JPEG compression, deliberate image tampered is studied and compared. The code is written in JAVA under Windows environment