The application implementation of IDEA algorithm in mobile E-commerce

（1. School of Business, Renming University, Beijing 100872, China;

2. School of Business Administration,AnHui University of Finance & Economics,Bengbu 233030 China;

3. Modern Education & Technology Center ,AnHui University of Finance & Economics,Bengbu 233030 China）

Abstract: The application of mobile E-commerce needs the encryption-decryption algorithm which is of high efficiency and reliability in order to make sure the security of data the in the process of transmission. IDEA algorithm can realize the encryption-decryption requirements of the mobile E-commerce in a relatively good manner. As for the JAVA language application platform, its disrelation has ensured that it can be applied widely in all types of mobile phones. Java applet, based on particular security model, is stored in the browser supported by Java, which can relatively well satisfy the security requirements of the mobile E-commerce.

Key words: IDEA; JAVA; mobile E-commerce

1. Introduction

With the rapid development of 3G network, mobile E-commerce has obtained wide application. The application of mobile E-commerce have brought relatively high requirement for the security of the data transmission. The encryption-decryption algorithm which is of high efficiency and reliability is required so as to protect key data such as users' information, order, sales and payment data and so on. At the same time, being restricted by the limited performance of terminal mobile phone equipments, the adopted encryption-decryption algorithm should be of light weight. Among a great many encryption-decryption algorithms, IDEA algorithm is a typical one in the application of mobile E-commerce. IDEA is short for International Data Encryption Algorithm. X.J.Lai and Massey, who are from Swiss Fed Inst Tech - Zurich Switzerland, put forward the suggestions that standard algorithm should be called as PES( Proposed Encryption Standard). Since it was born, IDEA has gone through a great deal of detailed investigations, proving that it does have strong resistance towards the code analysis. It has been widely applied in many mobile E-commerce products.

2. The descriptions of IDEA algorithm

2.1 MA module

IDEA code algorithm adopts （MA-Multiplication Addition） special network structure to realize the extension function. As for the design of any encryption-decryption algorithm, Confusion and Diffusion are the most important security characteristics. The mixture characteristics are realized through the following three kinds of functions.

1)Exclusive-OR, represented by .

2)Module 216(=MOD 65536), represented by picture.

3)Module 216+1(=mod 65537), represented by .

a (b+c) ≠(ab)+(ac)

a+(bc)≠(a+b)(a+c)

2.2 Description of encryption-decryption algorithm

(1)X1 multiples by Z1：H1（1）=X1（1）Z1

(2)X2 pulses Z2：H2（1）=X2（1）+Z2

(3) X3 pulses Z3：H3（1）=X3（1）+Z3

(4) X4 multiples by Z4：H4（1）=X4（1）Z4

（5）make（1）XOR（3）：H5（1）=H1（1）H3（1）

（6）make（2）XOR（4）：H6（1）=H2（1）H4（1）

（7） make（5）multiple by the fifth sub-key：H7（1）=H5（1）Z5（1）

（8） make（6）plus the results of（7）：H8（1）=H6（1）+H7（1）

（9） make the results of（8） multiple by the sixth sub-key：H9（1）=H8（1）Z6（1）

（10）make the results of（7）plus the results of（9）：H10（1）=H7（1）+H9（1）

（11）make the results of（1）XOR the results of（9）：H11（1）=H1（1）H9（1）

（12）make the results of（3）XOR the results of（9）：H12（1）=H3（1）H9（1）

（13）make the results of（2） plus the results of（10）的结果相异或：H13（1）=H2（1）H10（1）

（14）make the results of（4）XOR the results of（10）：H14（1）=H4（1）H10（1）

X1（2）==Y1（1）= H11，X2（2）=Y2（1）= H12，X3（2）=Y3（1）= H13，X4（2）=Y4（1）= H14

2.3 The production of subkey

Encryption is also used to protect data in transit, for example data being transferred via networks (e.g. the Internet, e-commerce), mobile telephones, wireless microphones, wireless intercom systems, Bluetooth devices and bank automatic teller machines. There have been numerous reports of data in transit being intercepted in recent years.[2] Encrypting data in transit also helps to secure it as it is often difficult to physically secure all access to networks.

The encryption-decryption sub-key to IDEA satisfies:

（1）（Zi(j)）-1 Zi(j)=1(mod216+1)

1≤i≤6,1≤j≤9

（2）-Zi(j) +Zi(j)=0(mod216)

1≤i≤6,1≤j≤9

2.4 The corresponding relationship table of encryption-decryption keys：

3. The Java program realization of IDEA under the mobile E-commerce environment

3.1 The corresponding relationship table of encryption-decryption keys：

private void idea_encrypt(int[] key, byte[] inbytes, byte[] outbytes)

{

int temp = 0;

int a1 = bytesToInt(inbytes, 0);

int b1 = bytesToInt(inbytes, 2);

int c1 = bytesToInt(inbytes, 4);

int d1 = bytesToInt(inbytes, 6);

for (int i = 0; i < 8; i++) //

{

A1 = x_multiply_y(a1, key[temp++]);

B1 += key[temp++];

B1 &= 0xffff;

C1+= key[temp++];

c1 &= 0xffff;

d1 = x_multiply_y(d1, key[temp++]);

int tmp1 = b1;

int tmp2 = c1;

c1 ^= a1;

b1 ^= d1;

c1 = x_multiply_y(c1, key[temp++]);

b1 += c1;

b1 &= 0xffff;

b1 = x_multiply_y(b1, key[temp++]);

c1 += b1;

c1 &= 0xffff;

a1 ^= b1;

d1 ^= c1;

b1 ^= tmp2;

c1 ^= tmp1;

}

intToBytes(x_multiply_y(a1, key[temp++]), outbytes, 0);

intToBytes(c1 + key[temp++], outbytes, 2);

intToBytes(b1 + key[temp++], outbytes, 4);

intToBytes(x_multiply_y(d1, key[temp]), outbytes, 6);

}

3.2 The production process of encryption

private int[] idea_encrypt_subkey(byte[] byteKey)

{

int[] key = new int[52];

if (byteKey.length < 16)

{

byte[] tmpkey = new byte[16];

System.arraycopy(byteKey, 0, tmpkey,

tmpkey.length - byteKey.length, byteKey.length);

byteKey = tmpkey;

}

for (int i = 0; i < 8; i++)

{

key[i] = bytesToInt(byteKey, i * 2);

}

for (int j = 8; j < 52; j++)

{

if ((j & 0x7) < 6) {

key[j] = (((key[j - 7] & 0x7f) > 7)) &

return key;

3.3 The production process of Decryption

private int[] idea_uncrypt_subkey(int[] key)

{

int dec = 52;

int asc = 0;

int[] unkey = new int[52];

int a2 = fun_a(key[asc++]);

int b2 = fun_b(key[asc++]);

int c2 = fun_b(key[asc++]);

int d2 = fun_a(key[asc++]);

unkey[--dec] = dd;

unkey[--dec] = cc;

for (int k1 = 1; k1 < 8; k1++)

{

A2 = key[asc++];

B2 = key[asc++];

unkey[--dec] = b2;

unkey[--dec] = a2;

a2 = fun_a(key[asc++]);

b2 = fun_b(key[asc++]);

c2 = fun_b(key[asc++]);

d2 = fun_a(key[asc++]);

unkey[--dec] = d2;

unkey[--dec] = b2;

unkey[--dec] = c2;

unkey[--dec] = a2;

a2 = fun_a(key[asc++]);

b2 = fun_b(key[asc++]);

c2 = fun_b(key[asc++]);

d2 = fun_a(key[asc]);

unkey[--dec] = d2;

unkey[--dec] = c2;

unkey[--dec] = b2;

unkey[--dec] = a2;

return unkey;

Acknowledgments.

Foundation project: Natural Science Foundation Project in Anhui Province (financial aid number: 11040606M140); Anhui University of Finance and Economics teaching and research project (financial aid number: ACJYYB201150，ACJYZD201122)；Anhui University of Finance and Economics scientific research project (financial aid number: ACKYQ1128)

4. Conclusions

The encryption speed of IDEA algorithm is fast. The production method of secret key is simple. Currently there have not been any apparent security holes. It is an algorithm that has been widely used. IDEA algorithm, based on JAVA, has wide prospect in the information security technology application in the mobile E-commerce system. This paper has brought out an algorithm based on IDEA, which has effectively improved the security of mobile E-commerce.

References

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[2]Suying Yang,Hongyan Piao,PLi Zhang,Xiaobing Zheng, An Improved IDEA Algorithm Based on USB Security Key ,IE Computer Society,pp.184-188, 2007.

[3]Rozza, Alessandro; Lombardi, Gabriele,IDEA: Intrinsic dimension estimation algorithm,Lecture Notes in Computer Science pp .433-442, 2011,

[4]Jogalekar, Usha A.; Mangla, Akhil,Proceedings, Idea generation algorithm based systems,2010 3rd IEEE International Conference on Computer Science and Information Technology, pP,14-17, 2010

[5]Cuizhi, Li; Yunkang,Yue,A study on key technologies in the development of mobile e-commerce,2011 International Conference on E-Business and E-Government, pp 6706-6709, 2011.

[6]Jun, Wang,A research on Mobile E-Commerce security,2011 International Conference on Internet Technology and Applications, 2011.