Reversible Data Hiding in Encrypted Image based on Homomorphic Public Key Cryptosystem
Reversible Data Hiding in Encrypted Image based on Homomorphic Public Key Cryptosystem
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发表时间：
2016
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通讯作者：
Shi-Jun Xiang;Xin-Rong Lou
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作者：
Shi-Jun Xiang;Xin-Rong Lou
同态加密技术能够有效地保护用户的隐私，并且可以直接在密文中进行代数运算，是云计算领域的研究热点。由于云计算环境下的安全威胁，加密数据的安全保护和完整性认证一直是一个亟待解决的问题。此外，挑战在于如何检索加密数据。为了实现对加密图像的有效管理及其安全保护,提出了一种基于同态加密系统的图像可逆信息隐藏算法.该算法首先在加密前根据密钥选择目标像素,并利用差分扩展DE(difference expansion)的方法将目标像素的各比特数据嵌入到其他像素中.该算法的优点是，通过将秘密数据的伪像素点替换为目标像素点，可以将秘密数据直接嵌入同态加密域中。利用法律的密钥，接收者可以从加密图像和直接解密图像中提取嵌入数据。此外，他/她可以在解密和数据提取后完美地恢复原始图像。实验结果表明，在同态加密域中，在保持数据量不变的情况下，可以更有效地嵌入额外的数据。此外，嵌入数据可以在密文和明文两种形式下提取。
Homomorphic encryption, which protects privacy effectively and allows algebraic operations directly in the ciphertext, has been a hot spot in the study of cloud computing. Due to security threats in cloud computing, the security protection and integrity authentication of encrypted data remain grave problems. Besides, the challenge lies in how to retrieve the encrypted data. To achieve more effective management and security protection of encrypted images on-line, this paper proposes a reversible data hiding scheme for ciphertext based on the public key cryptosystems with homomorphic and probabilistic properties. In the proposed scheme, partial pixels are selected as target pixels by a secret key and all bits of the target pixels are embedded into the other pixels with difference expansion (DE) to vacate room before encryption. As a bonus, secret data can be embedded directly in homomorphic encrypted domain by altering the target pixels with the fake pixels which are comprised of secret data. With the legal key, the receiver can extract the embedded data from the encrypted image and the directly decrypted image. Furthermore, he/she can recover the original image perfectly after decryption and data extraction. Finally, experimental results show that extra data can be embedded more efficiently in homomorphic encrypted domain while keeping the quantity of data unchanged. Besides, the embedded data can be extracted in both ciphertext and plaintext.