Selective-encrypted GIS vector map with low complexity

Recently years, vector map has many advantages than raster map when it is used in many domains as research, education, military or digital map services. And in most cases vector map data contains confidential information which must be kept away from unauthorized users. Moreover, the producing process of a vector map is considerably complex, and the maintenance of a digital map requires substantial monetary, human resources. With the rapid development of vector map contents, a large volume of valuable vector map dataset has been illegal distributed by pirates, hackers or unauthorized users. Therefore the problem focuses on how to protect the vector map data for multimedia applications, storage and transmission. This paper presents the selective encryption algorithm for vector map protection for storage, transmission, distribution to authorized users. In proposed algorithm, we just select some values of polylines and polygons in DCT domain to encrypt by random algorithms and cryptography. Experimental results verified that proposed algorithm is effectively and security. Maps are changed whole after encryption process, and unauthorized users cannot access to copy or use them. Encrypted maps do not alter the size of file and it does not have loss accuracy. The error between original map and decrypted map is approximate zero.