Abstract
This paper introduces approximate image message authentication codes IMACs) for soft image authentication. The proposed approximate IMAC survives small to moderate image compression and it is capable of detecting and locating tampering. Techniques such as block averaging and smoothing, parallel approximate message authentication code (AMAC) computation, and image histogram enhancement are used in the construction of the approximate IMAC. The performance of the approximate IMAC in three image modification scenarios, namely, JPEG compression, deliberate image tampering, and additive Gaussian noise, is studied and compared. Simulation results are presented.