随着云计算的发展, 越来越多的多媒体数据存储在云端, 出于安全需要, 往往需要对其加密后再上传至云端进行存储或运算等操作. 针对加密图像, 在不具备图像明文内容的情况下, 为了认证图像内容的完整性和真实性, 提出了一种基于Paillier同态加密的鲁棒图像哈希算法. 该算法主要由3个部分构成: 图像所有者端图像加密, 云服务器端密文图像哈希计算以及接收者端明文图像哈希生成. 具体地, 图像所有者对图像进行Paillier加密, 并将加密图像上传至云服务器, 由云服务器利用Paillier密码系统的运算法则执行加密域DCT与Watson人眼视觉特征等的计算, 并利用密钥控制的伪随机矩阵增加哈希的随机性, 接收者解密并分析接收到的密文哈希, 生成明文图像哈希. 实验结果表明, 所提算法在鲁棒性、唯一性和安全性上具有较理想的性能.
With the development of cloud computing, more and more multimedia data is stored in the cloud. For security needs, it is often necessary to encrypt images before uploading them to the cloud for storage or computing operations. Without knowing the plaintext content of the encrypted image, in order to verify the integrity of the image information and the authenticity of the content, an image hash algorithm based on Paillier homomorphic encryption is proposed. The algorithm is mainly composed of three parts: the image owner encrypts the image, the cloud server generates a ciphertext image hash, and the receiver generates a plaintext image hash. Specifically, the image owner encrypts the image and uploads the encrypted image to the cloud server. The cloud server uses the algorithm of the Paillier cryptosystem to perform calculations of DCT and Watson human visual features in encrypted domain, and uses a key-controlled pseudo-random matrix to increase the randomness of the ciphertext hash, thereby improving the security of the hash. The receiver decrypts and analyzes the received ciphertext hash to obtain the plaintext image hash. Experimental results show that the proposed algorithm has ideal performance in terms of robustness, uniqueness, and security.