1. Security Protection of Software Programs by Information Sharing and Authentication Techniques Using Invisible ASCII Control Codes Authors : I-Shi Lee and Wen-Hsiang Tsai Source : International Journal of Network Security, vol. 10, no. 1, pp. 1-10, 2010 Presenter : Ping-Kun Hsu ( 許鈵昆 ) Date : 11/26/2010

2. Outline  Introduction  ASCII control codes  The proposed method  Experimental result  Conclusions 2

3. Introduction  Goals  Information Sharing  Authentication  Related Works  Invisible Character Coding Table  Exclusive-OR 3

4. ASCII control codes(1/2) HexCharHexCharHexCharHexChar 0NUL8BS10DLE18CAN 1SOH9HT11DC119EM 2STXALF12DC21ASUB 3ETXBVT13DC31BESC 4EOTCFF14DC41CFS 5ENQDCR15NAK1DGS 6ACKESO16SYN1ERS 7BELFSI17ETB1FUS 4 invisible in the comments or characters string of VC++ programs

5. ASCII control codes(2/2) 5

6. The proposed method(1/8)  Invisible Character Coding Table 6 HexInvisible ASCII CodeBit Pair 1CFS00 1DGS01 1ERS10 1FUS11

7. The proposed method(2/8)  Flow Chat 7 Secret program Camouflage programs Secret random key ⊕ ⊕ Shares Authentication signs Stego-programs Invisible Character Coding Table

8. The proposed method(3/8)  Creating shares from the secret program  S s : Secret program string  P k : Camouflage program,, k = 1, 2, …, n  S k : Camouflage programs string, k = 1, 2, …, n  Y’: The expanded key  E k : The shares, k = 1, 2, …, n 8 S 1 S 2 S 3 S n-1 S n S s ⊕⊕⊕⊕‧‧‧⊕⊕⊕ Y’ E E 1 E 2 E n-1 E 3 E n ‧‧‧ = E P k = c 1 c 2 c 3 … S k

9. The proposed method(4/8)  Generating authentication signs  S k : Camouflage programs string, k = 1,2, …, n  E k : The shares, k = 1, 2, …, n  A k : The authentication signs, k = 1, 2, …,n  Y : The secret random key 9 S k E k Y = (ABC) 16 =(65 66 67) 10 = (10101010) 2 = (170) 10 = (DEF) 16 =(68 69 70) 10 65+66+67 mod 170 = 28 68+69+70 mod 170 = 37 00011100 00100101 = A k

10. The proposed method(5/8)  Encoding and hiding the shares and signs  E k : The shares, k = 1, 2,…, n  A k : The authentication signs, k = 1, 2,…, n  F k : Binary string, k = 1, 2,…, n  P k : Camouflage program,, k = 1, 2, …, n  P k ’: Stego-programs, k = 1, 2, …, n 10 E k A k F k =|| = 01000100 01000101 01000110 00011100 00100101 Invisible character coding table 1D1C1D1C 1D1C1D1D 1D1C1D1E 1C1D1F1C 1C1E1D1D P k Pk’ Pk’

11. The proposed method(6/8) 11  Extracting hidden shares and signs  E k : The shares, k = 1, 2,…, n  A k : The authentication signs, k = 1, 2,…, n  F k ’: The extracted character string, k = 1, 2,…, n  P k : Camouflage program,, k = 1, 2, …, n  P k ’: Stego-programs, k = 1, 2, …, n Pk’ Pk’ P k 1D1C1D1C 1D1C1D1D 1D1C1D1E 1C1D1F1C 1C1E1D1D = F k ’ || Invisible character coding table F k ’ = 01000100 01000101 01000110 00011100 00100101 E k A k

12. The proposed method(7/8)  Authenticating  E k : The shares, k = 1, 2,…, n  A k ’: The authentication signs, k = 1, 2,…, n  P k : Camouflage program,, k = 1, 2, …, n  S k : Camouflage programs string, k = 1, 2, …, n  Y : The secret random key 12 =00011100 00100101 A k ’ A k = 00011100 00100101 P k = c 1 c 2 c 3 … S k E k = (ABC) 16 =(65 66 67) 10 = (DEF) 16 =(68 69 70) 10 65+66+67 mod 170 = 28 68+69+70 mod 170 = 37 Y = (10101010) 2 = (170) 10 00011100 00100101 = A k ’

13. The proposed method(8/8)  Recovering the secret program  S s : Secret program string  S k : Camouflage programs string, k = 1, 2, …, n  Y’: The expanded key  E k : The shares, k = 1, 2, …, n 13 E E 1 E 2 E n-1 E 3 E n ‧‧‧ || = S s ⊕ S 1 S 2 S 3 S n-1 S n ⊕⊕⊕⊕‧‧‧⊕⊕ Y’ = E

14. Experimental result 14

15. Conclusions 15  The proposed method may decrease the doubts of malicious attackers.  The proposed method may be extended to deal with web pages.