Perceptual Encryption Method for Vector Map Based on Geometric Transformations Giao P.N 1 , Oh-Jun Kwon 2 , Suk-Hwan Lee 3 and Ki-Ryong Kwon 4 1, 4 Dept. of IT Convergence & Application Engineering, Pukyong National University, Pusan, South Korea 2 Dept. of Computer Software Engineering, Dong-Eui University, Pusan, South Korea 3 Dept. of Information Security, Tongmyong University, Pusan, South Korea E-mail: [email protected], [email protected], [email protected], [email protected]Abstract β Currently, there are many applications used vector map data widely. But the production of vector map consumes a lot of money and human resource while vector map data is bought by any user or attacked by pirates, and then they distributed vector map data easily without permission from providers. So, provider desires a method to encrypt vector map data before storing and transmitting to ensure the access control and prevent illegal copying of it. This paper presents a perceptual encryption method for vector map data based on encrypting geometric objects in the frequency domain of discrete cosine transform. Geometric objects in vector map are changed by geometric transformations. After that, they are encrypted selectivity in the frequency domain of discrete cosine transform to obtain encrypted objects. In experiments, vector map data is changed entirely after encryption process, and the proposed method is very effective for a large of vector map datasets. I. INTRODUCTION Vector map data is a vectorβbased collection of Geographic Information System (GIS) data about earth at various levels of detail. Vector map is created and developed by the merging system of cartography, statistical analysis, and database technology based on vector model [1-2]. Because it has more advantages than raster map, vector map is used in many applications in life. But the production of a vector map is considerably complex, and the maintenance of a digital map requires substantial monetary, human resources. And any company can buy it, make illegal copies and distribute or sell them easily many times without taking any permission from the original GIS data provider. So, producer or provider desires a method to encrypt vector map data before storing and transmitting to ensure the access control and prevent illegal copying of it. For meeting above requirement, in this paper we present a perceptual encryption method for vector map data for the secured storage and transmission. In the proposed method, we selected and changed the geometric objects of vector map data by geometric transformation, and then we encrypt them selectivity in the frequency domain of discrete cosine transform (DCT). The main advantages of our algorithm is simple computing but it still meets requirements of security, and it can be applied to the various formats of vector map data. In order to understand the detailed content of algorithm, our paper is organized as follows. In section 2, we look into the vector map security techniques and discuss the relation of vector map data to the proposed scheme. In section 3, we explain the proposed algorithm in detail. And section 4, we perform experiments and discuss about the experimental results, evaluate the performance of algorithm. Conclusion is shown in section 5 in this paper. II. RELATED WORKS A. Vector Map Encryption Bertino et al. [3], Chena et al. [4], and Rybalov et al. [5] presented approaches to the definition of an access control system for spatial data on the Web. Mostly, authors explained technical challenges raised by the unique requirements of secure geospatial data management such as access control, security and privacy policies. But access control and management on Web or database do not maintain security in the outflow of an authenticated user. Wu et al. [6] proposed a compound chaos-based encryption algorithm of vector data by considering the storage characteristics and sensitivity of the initial values and parameters of chaos-based systems. This algorithm is not available to various data formats and object indexing. Li et al. [7] encrypted the vector dataset in external Oracle DBMS by using DES and an R-Tree spatial index. This algorithm does not keep the security of the vector map on the DBMS because key length is short. Dakroury et al. [8] also described better encrypting algorithm which combined AES and RSA cryptography with a simple watermarking technique for the copyright protection of vector map data in on/off line service. This algorithm encrypts all parts of vector map data using an AES block cipher operator of 256 bits. That mean it encrypted unnecessary data of vector map data. B. Vector Map Data Based Perceptual Encryption Vector map data is stored in layers. Each layer includes an amount of vector data which is described by geometric objects as point, polyline and polygon. Point is used to represent simple objects as position while polygon and polyline are used to represent complex objects as road, contour line and boundaries [9]. Real objects are described on the map based on geographical features and by geometric objects. So, vector map encryption should be based on them. Thus, polyline and polygon are considered be very important components of vector map. In our method, polyline and polygon data in layer is selected and extracted for perceptual encryption.
4
Embed
Perceptual Encryption Method for Vector Map Based on ...
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Perceptual Encryption Method for Vector Map Based
on Geometric Transformations
Giao P.N 1, Oh-Jun Kwon 2, Suk-Hwan Lee 3 and Ki-Ryong Kwon 4 1, 4 Dept. of IT Convergence & Application Engineering, Pukyong National University, Pusan, South Korea
2 Dept. of Computer Software Engineering, Dong-Eui University, Pusan, South Korea 3 Dept. of Information Security, Tongmyong University, Pusan, South Korea
Abstract β Currently, there are many applications used vector
map data widely. But the production of vector map consumes a
lot of money and human resource while vector map data is bought
by any user or attacked by pirates, and then they distributed
vector map data easily without permission from providers. So,
provider desires a method to encrypt vector map data before
storing and transmitting to ensure the access control and prevent
illegal copying of it. This paper presents a perceptual encryption
method for vector map data based on encrypting geometric
objects in the frequency domain of discrete cosine transform.
Geometric objects in vector map are changed by geometric
transformations. After that, they are encrypted selectivity in the
frequency domain of discrete cosine transform to obtain
encrypted objects. In experiments, vector map data is changed
entirely after encryption process, and the proposed method is very
effective for a large of vector map datasets.
I. INTRODUCTION
Vector map data is a vectorβbased collection of Geographic
Information System (GIS) data about earth at various levels of
detail. Vector map is created and developed by the merging
system of cartography, statistical analysis, and database
technology based on vector model [1-2]. Because it has more
advantages than raster map, vector map is used in many
applications in life. But the production of a vector map is
considerably complex, and the maintenance of a digital map
requires substantial monetary, human resources. And any
company can buy it, make illegal copies and distribute or sell
them easily many times without taking any permission from the
original GIS data provider. So, producer or provider desires a
method to encrypt vector map data before storing and
transmitting to ensure the access control and prevent illegal
copying of it.
For meeting above requirement, in this paper we present a
perceptual encryption method for vector map data for the
secured storage and transmission. In the proposed method, we
selected and changed the geometric objects of vector map data
by geometric transformation, and then we encrypt them
selectivity in the frequency domain of discrete cosine transform
(DCT). The main advantages of our algorithm is simple
computing but it still meets requirements of security, and it can
be applied to the various formats of vector map data. In order
to understand the detailed content of algorithm, our paper is
organized as follows. In section 2, we look into the vector map
security techniques and discuss the relation of vector map data
to the proposed scheme. In section 3, we explain the proposed
algorithm in detail. And section 4, we perform experiments and
discuss about the experimental results, evaluate the
performance of algorithm. Conclusion is shown in section 5 in
this paper.
II. RELATED WORKS
A. Vector Map Encryption
Bertino et al. [3], Chena et al. [4], and Rybalov et al. [5]
presented approaches to the definition of an access control
system for spatial data on the Web. Mostly, authors explained
technical challenges raised by the unique requirements of
secure geospatial data management such as access control,
security and privacy policies. But access control and
management on Web or database do not maintain security in
the outflow of an authenticated user. Wu et al. [6] proposed a
compound chaos-based encryption algorithm of vector data by
considering the storage characteristics and sensitivity of the
initial values and parameters of chaos-based systems. This
algorithm is not available to various data formats and object
indexing. Li et al. [7] encrypted the vector dataset in external
Oracle DBMS by using DES and an R-Tree spatial index. This
algorithm does not keep the security of the vector map on the
DBMS because key length is short. Dakroury et al. [8] also
described better encrypting algorithm which combined AES
and RSA cryptography with a simple watermarking technique
for the copyright protection of vector map data in on/off line
service. This algorithm encrypts all parts of vector map data
using an AES block cipher operator of 256 bits. That mean it
encrypted unnecessary data of vector map data.
B. Vector Map Data Based Perceptual Encryption
Vector map data is stored in layers. Each layer includes an
amount of vector data which is described by geometric objects
as point, polyline and polygon. Point is used to represent simple
objects as position while polygon and polyline are used to
represent complex objects as road, contour line and boundaries
[9]. Real objects are described on the map based on
geographical features and by geometric objects. So, vector map
encryption should be based on them. Thus, polyline and
polygon are considered be very important components of
vector map. In our method, polyline and polygon data in layer
is selected and extracted for perceptual encryption.
Fig. 1 The proposed algorithm.
III. THE PROPOSED METHOD
A. Overview
The proposed method is shown detail in Fig. 1. Geometric
objects (polyline and polygon) are extracted from vector map
data, and they are used together with key value to generate
shearing vector. Next, geometric objects are distorted by
distorting process using shearing vector. After that, distorted
object will be transform to DCT domain by forward DCT
process. In DCT domain, we perform selective encryption for
DCT coefficients. DC value is selected for encryption process
in DCT domain. Due to DC value was changed by encryption
process, after inverse DCT process, we get new geometric
object. Finally, we continue to use shearing vector for
distorting process new object above to obtain encryption object.
B. Perceptual encryption process
A vector map contains number of layers. We consider a layer
π³ contains a number of objects of polylines/polygons π³ ={ππ|π β [1, |π³|]}, and an object contains a series of vertices ππ ={π£π,π|π β [1, |ππ|]}. |L| and |ππ| are cardinalities of a layer L, and
an object ππ . Thus, π£π,π indicates ππ‘β vertex in ππ‘β object of
layer L and is defined as two coordinates π£π,π = (π₯π,π , π¦π,π). To
brief, we define main notation following theory above:
An object ππ = {π£π,π|π β [1, |ππ|]}
Shearing vector for ππ is ππ = {π π,π|π β [1, |ππ|]}
π is key value for encryption object, is created by hashing
function
πβ²π = {π£β²π,π|π β [1, |ππ|]} is distorted object
π π = {ππ,π|π β [1, |ππ|]} is a set of DCT coefficients of
distorted object after DCT process
π β²π = {πβ²π,π
|π β [1, |ππ|]} is a set of DCT coefficients of
object after inverse DCT
ππ = {ππ,π|π β [1, |ππ|]} is encrypted object
π·πΆπ, πΌπ·πΆπ are forward and inverse DCT process
π·(. ) is distorting process
Shearing vector ππ is a set of values that they are generated
by key value K and parameter the number of vertices in object
ππ by (1). Key value K is created by SHA-512 hashing
algorithm from user key with key length is 512 bit for each key