A Secure and Robust DCT-Based Hashing Scheme for Image Authentication

The purpose of an image hash function is to provide a compact representation of an image that can be used for authentication purposes. Designing a good image hash function requires the consideration of many issues like robustness, security and tamper detection with precise localization. In this paper, we focus our attention towards DCT-based hashing schemes for image authentication. We first highlight the problems that we have discovered in some of the existing DCT-based hashing schemes proposed in the literature. We then propose solutions to counter these problems. We present experimental results to show the effectiveness of our proposed scheme. Although we focus on DCT-based hashing techniques, however, the type of problems highlighted in this paper may be present in other spatial or transform domain image hashing techniques as well