随着互联网技术和分布式数据存储的高速发展，企业对云平台使用越来越普及。与此同时，人们对于自身存储在云平台的数据安全的关心程度也前所未有, 对云平台上存储的数据安全有了更高的要求。 Hadoop能够让用户轻松架构和使用分布式平台，然后通过该平台对大量数据进行分布式处理。但是基于Hadoop的分布式数据存储目前存在着很大的安全隐患，缺少对静态数据的加密保障，在安全方面只关注了数据的验证和备份等部分，并没有注重数据本身的安全性，因此频频爆发安全问题。本文研究的主要内容就是将加密技术应用到Hadoop云平台中，能够实现对存储在Hadoop云平台的数据进行分布式的对称加密和解密。 首先，本论文在介绍了云计算和分布式数据存储的国内外研究现状和发展趋势后，对Hadoop开源平台的两大关键技术：分布式文件系统HDFS（Hadoop Distributed Filesystem）和用于处理海量数据的编程模型MapReduce做了详细的介绍。 其次，通过对现有加密算法的对比，分析传统分布式数据存储和Hadoop分布式数据存储存在的问题，本文结合Hadoop分布式云计算框架中的的MapReduce模型，总结得出了基于Hadoop的分布式对称加密数据存储技术，并进行了简要的分析。 然后，从整体上对数据的分布式加密和解密各个模块进行了设计，并详细介绍了用MapReduce实现对称加密AES（Advanced Encryption Standard）算法过程，特别是着重介绍和设计了能够实现该算法的Map函数和Reduce函数。 最后，在实验室内搭建Hadoop集群，并且通过该云平台，来实现加密和解密过程，并对分布式对称加密算法进行功能测试、扩展性测试和效率测试，验证整个流程。通过比较测试数据给出仿真性能分析，提出优化问题，并对工作进行了总结和展望。

With the rapid development of Internet technology and distributed data storage, the usage of the cloud platform is becoming more and more popular between the enterprises. At the same time, the interest of the data which are stored in the cloud platform has been raised to an extremely high level by the datas’ owner. People have higher requirements about the security of cloud platform data storage. Hadoop allows users to architect and use the distributed platform easily, and then process lots of massive information distributed. But the data storage based on Hadoop has big security problems currently and is lack of static data encryption. About the security part, it only focuses on the validation and backup of data, but pay no attention to the security of cloud files itself. So security issues frequently come out. The main content of this paper is to apply the encryption technology to Hadoop cloud platform, and achieve the goal of distributed and symmetric encrypting the data which are stored in the cloud platform, in order to improve the security of the data in the cloud. First of all, this paper introduces the present domestic and foreign research, situation and development trend of the cloud computing and distributed data storage. Make a detailed explanation about the two key technologies of Hadoop open resource platform: the Hadoop Distributed Filesystem(HDFS) and the MapReduce programming model. Secondly, through the comparison of the existing encryption algorithms and the analysis of the problems in traditional distributed data storage and HDFS, the paper combined with the programming model of Hadoop distributed clusters,and summarized a symmetrically encrypted data technology based on it. At the same time, give it a brief analysis. Then the paper designed each part of the new module, and introduced the entire process of using the MapReduce to implement the encryption AES(Advanced Encryption Standard), especially focuses on the realization of the relevant mapping and reducing function. Finally, build a real Hadoop cloud computing platform through the virtual machine in laboratory to achieve the process of encryption and decryption. And verify the whole process by function, expansion and efficiency test. By comparing the test data, the paper showed analysis of the simulation performance and put forward the optimization. At last, it gives the summary and outlook of the work.