Big blocks or blocks relation techniques are applied in several image authentication schemes to improve security at the cost of localization accuracy is decreased.In this paper

an image authentication scheme based on fragile watermarking is proposed by means of the analysis of all kinds of attacks.On the basis of small blocks

the strong cryptography algorithm is applied

the watermarking is generated by SHA512 and one-way function based on knapsack problem

and is embedded via sliding window and hierarchical structure.The approach can not only resists all kinds of attacks such as vector quantization(VQ)

but also localize a tamper to a 2×2 block pixels.Theory analysis and experimental results demonstrate that the proposed scheme improves the accuracy of tamper localization as well as ensure the security.