利用哈尔变换和高斯随机数进行矢量空间数据坐标加密

基于安全保密的考虑，需要对矢量空间数据进行加密，现有做法是对数据文件整体进行加密，会破坏矢量空间数据结构并影响属性数据的查看。提出了一种不改变矢量空间数据结构，仅对坐标数据加密的方法，能够保护数据的安全且矢量数据结构依然保持不变。运用SHA-512加密用户密钥得到哈希密钥，用高斯随机数置乱哈希密钥生成用来加密坐标数据的密钥。首先读取矢量空间数据的顶点序列，并对矢量数据的顶点坐标序列进行哈尔变换，使用上述密钥对哈尔变换后的均值系数和差值系数进行加密，再实施逆哈尔变换得到加密后坐标，使用高斯随机数置乱顶点序列得到加密后的矢量空间数据。实验结果表明，矢量空间数据的坐标被加密，但文件结构及属性数据完全保持不变，且运行效率高；拥有密钥的用户还可以解密坐标，还原出原始矢量空间数据，安全性高。

A Coordinate Encryption Algorithm for Vector Spatial Data Using Haar Transform and Gaussian Random Number

  Objectives  Security of vector spatial data is of importance in the community of geographic information sciences. It is necessary to encrypt the vector spatial data based on the consideration of data security. The existing method is to encrypt the entire data file, which affects the view of attribute data and destroys vector spatial data structure.  Methods  A coordinate encryption method which does not change the structure of vector spatial data file is proposed, which not only protects the security of data, but also has no impact on the normal use of data. Firstly, vector spatial data are encrypted in Haar transform domain by the secret key. The secret key used to encrypt the coordinate data is generated combined Hash key with Gaussian random number. The average coefficient and the differential coefficient are obtained from Haar transformation of the vertex sequence of vector spatial data and are encrypted by the secret key. After that, the encrypted coordinates are obtained by Haar inverse transformation of data. Finally, the Gaussian random number is utilized to scramble the vertex sequence in order to get the encrypted disordered vector spatial data.  Results  The experimental results show that: (1)The structure and attribute data of the vector spatial data file are completely unchanged after encryption, only the coordinates are encrypted, and efficiency is improved. (2) The algorithm can effectively decrypt and restore the original vector spatial data, with high security.  Conclusions  The proposed method can not change the structure of vector spatial data, and the efficiency of encryption is improved.