Masayuki Suto

A new semi-fragile image authentication framework combining ECC and PKI infrastructures

Presents a new semi-fragile framework aiming at extending public key signature scheme from message level to content level. The content signing procedure includes signature generation and watermark embedding while the content authentication procedure includes watermark extraction and signature verification. One main unique contribution is the novel use of error correction coding (ECC) to address the incidental distortions caused by some acceptable manipulations such as lossy compression. Another unique feature is integration of PKI security infrastructure and the hashing mechanism to achieve security and short signatures/watermarks. In the signing procedure, block-based invariant features are extracted from the image content and then encoded by ECC to obtain their corresponding parity check bits (PCB). All PCBs are then embedded back into image as watermarks for the purpose of authentication and locating content alteration. In addition, codewords are concatenated, hashed and finally signed by content owners private key to generate a global cryptographic signature. The authentication procedure is the inverse procedure of signing except using content owners public key for signature verification.

A quantitative semi-fragile JPEG2000 image authentication system

We propose a novel integrated approach to quantitative semi-fragile authentication of JPEG2000 images under a generic framework which combines ECC and PKI infrastructures. Firstly acceptable manipulations (e.g., re-encoding) which should pass authentication are defined based on considerations of some target applications. We propose a unique concept of lowest authenticable bit rate - images undergoing repetitive re-encoding are guaranteed to pass authentication provided the re-encoding rates are above the lowest allowable bit rate. Our solutions include computation of content-based features derived from the EBCOT encoding procedure of JPEG2000, error correction coding of the derived features, PKI cryptographic signing, and finally robust embedding of the feature codes into image as watermarks.

New semifragile image authentication watermarking techniques using random bias and nonuniform quantization

Semi-fragile watermarking techniques aim at detecting malicious manipulations on an image, while allowing acceptable manipulations such as lossy compression. Although both of these manipulations are considered to be pixel value changes, semi-fragile watermarks should be sensitive to malicious manipulations but robust to the degradation introduced by lossy compression and other defined acceptable manipulations. In this paper, after studying the characteristics of both natural images and malicious manipulations, we propose two new semi-fragile authentication techniques robust against lossy compression, using random bias and nonuniform quantization, to improve the performance of the methods proposed by Lin and Chang.