Authors : I-Shi Lee and Wen-Hsiang Tsai

Security Protection of Software Programs by Information Sharing and Authentication

Techniques Using Invisible ASCII Control Codes

Authors : I-Shi Lee and Wen-Hsiang TsaiSource : International Journal of Network Security, vol. 10, no. 1, pp. 1-10, 2010Presenter : Ping-Kun Hsu (許鈵昆 )Date : 11/26/2010

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Outline Introduction ASCII control codes The proposed method Experimental result Conclusions

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Introduction Goals

Information Sharing Authentication

Related Works Invisible Character Coding Table Exclusive-OR

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ASCII control codes(1/2)

Hex Char Hex Char Hex Char Hex Char

0 NUL 8 BS 10 DLE 18 CAN

1 SOH 9 HT 11 DC1 19 EM

2 STX A LF 12 DC2 1A SUB

3 ETX B VT 13 DC3 1B ESC

4 EOT C FF 14 DC4 1C FS

5 ENQ D CR 15 NAK 1D GS

6 ACK E SO 16 SYN 1E RS

7 BEL F SI 17 ETB 1F US

invisible in the comments or characters string of VC++ programs

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ASCII control codes(2/2)

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The proposed method(1/8) Invisible Character Coding Table

Hex Invisible ASCII Code Bit Pair

1C FS 00

1D GS 01

1E RS 10

1F US 11

The proposed method(2/8) Flow Chat

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Secret program Camouflage programs Secret random key

⊕ ⊕

Shares

Authentication signs

Stego-programs

Invisible Character Coding Table

The proposed method(3/8) Creating shares from the secret program

Ss : Secret program string Pk: Camouflage program, , k = 1, 2, … , n Sk: Camouflage programs string, k = 1, 2, …, n Y’: The expanded key Ek: The shares, k = 1, 2, …, n

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S1 S2 S3 Sn-1 Sn Ss⊕ ⊕ ⊕ ⊕‧‧‧ ⊕ ⊕⊕ Y’

E E1 E2 En-1 E3 En‧‧‧

= E

Pk = c1c2c3 … Sk

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The proposed method(4/8) Generating authentication signs

Sk: Camouflage programs string, k = 1 ,2, …, n Ek: The shares, k = 1, 2, …, n Ak: The authentication signs, k = 1, 2, … ,n Y : The secret random key

Sk

Ek

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 = Ak

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The proposed method(5/8) Encoding and hiding the shares and signs

Ek: The shares, k = 1, 2,…, n Ak: The authentication signs, k = 1, 2,… , n Fk: Binary string, k = 1, 2,… , n Pk: Camouflage program, , k = 1, 2, … , n Pk’: Stego-programs, k = 1, 2, … , n

Ek Ak Fk = ||

= 01000100 01000101 01000110 00011100 00100101

Invisible character coding table

1D1C1D1C 1D1C1D1D 1D1C1D1E 1C1D1F1C 1C1E1D1D

Pk Pk’

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The proposed method(6/8) Extracting hidden shares and signs

Ek: The shares, k = 1, 2,…, n Ak: The authentication signs, k = 1, 2,… , n Fk’: The extracted character string, k = 1, 2,… , n Pk: Camouflage program, , k = 1, 2, … , n Pk’: Stego-programs, k = 1, 2, … , n

Pk’ Pk

1D1C1D1C 1D1C1D1D 1D1C1D1E 1C1D1F1C 1C1E1D1D

= Fk’||

Invisible character coding table

Fk’ =

01000100 01000101 01000110 00011100 00100101

Ek Ak

The proposed method(7/8) Authenticating

Ek: The shares, k = 1, 2,…, n Ak’: The authentication signs, k = 1, 2,… , n Pk: Camouflage program, , k = 1, 2, … , n Sk: Camouflage programs string, k = 1, 2, …, n Y : The secret random key

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=00011100 00100101 Ak’

Ak = 00011100 00100101 Pk = c1c2c3 … Sk

Sk

Ek

= (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 = Ak’

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The proposed method(8/8) Recovering the secret program

Ss : Secret program string Sk: Camouflage programs string, k = 1, 2, …, n Y’: The expanded key Ek: The shares, k = 1, 2, …, n

E E1 E2 En-1 E3 En‧‧‧|| || || || =

Ss⊕ S1 S2 S3 Sn-1 Sn

⊕ ⊕ ⊕ ⊕‧‧‧ ⊕ ⊕ Y’= E

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Experimental result

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Conclusions The proposed method may decrease the

doubts of malicious attackers.

The proposed method may be extended to deal with web pages.