Abstract:

With the popularity of cloud storage services and telemedicine platforms， more and more medical images are uploaded to the cloud. After being uploaded， the uploaded medical images may be leaked to unauthorized third parties， resulting in the disclosure of users’ personal privacy. Besides， if medical images are only uploaded to a single server for storage， they are vulnerable to attacks resulting in the loss of all data. To solve these problems， a medical image privacy protection algorithm based on thumbnail encryption and distributed storage was proposed. Firstly， by encrypting the thumbnail of the original medical image， the relevance of the medical images was preserved properly while achieving the encryption effect. Secondly， the double embedding method was adopted when hiding secret information， and data extraction and image recovery were performed separately to achieve Reversible Data Hiding （RDH） of the encrypted image. Finally， the distributed storage method based on polynomial shared matrix was used to generate n shares of the image and distribute them to n servers. Experimental results show that by using the encrypted thumbnail as carrier， the proposed algorithm exceeds the traditional security encryption methods on embedding rate. Even if the server is attacked， the receiver can recover the original image and private information as long as it receives no less than k shares. In the privacy protection of medical images， experiments were carried out from the aspects of anti-attack and image recovery， and the analysis results show that the proposed encryption algorithm has good performance and high security.

Key words: thumbnail encryption, Reversible Data Hiding (RDH), secret sharing, distributed storage, privacy protection

摘要：

随着云存储服务和远程医疗平台的日益盛行，越来越多医学图像被上传至云端，这些上传的医学图像存在被泄露给未经授权的第三方的风险，造成用户的个人隐私泄露。此外，如果医学图像仅上传至单个服务器进行存储，容易被攻击，进而导致全部数据的丢失。针对这些问题，提出一种基于缩略图加密和分布式存储的医学图像隐私保护算法。首先，通过对原始医学图像进行缩略图加密，在实现加密效果的同时适当保留图像的相关性；其次，在隐藏秘密信息时采用双嵌入法，并分别进行数据提取和图像恢复，从而实现加密图像的可逆信息隐藏（RDH）；最后，采用基于多项式共享矩阵的分布式存储方法将图像生成n个不同份额，并分发至n个服务器。实验结果表明，所提算法使用加密后的缩略图作为载体后的嵌入率高于传统安全加密方法；即使服务器受到攻击，接收方只要接收不少于k个份额就可以恢复原始图像和隐私信息。在医学图像的隐私保护上，从抗攻击、图像的恢复等方面进行了实验，分析结果表明所提加密算法性能良好，具有较高的安全性。

关键词: 缩略图加密, 可逆信息隐藏, 秘密共享, 分布式存储, 隐私保护