A study for Relational Database watermarking scheme

Speaker: Pei-Feng Shiu

Date: 2012/09/21

Outline

• Introduction• Relational Database watermarking schemes• Discussion

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Introduction• Image

– Pixel(0-255)• Database

– Textual data– Numerical data

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Pixel blocks

Coefficient blocks

Compression code

Primary key Attribute1 Attribute2 Attribute3 Attribute4

Tuple 1 1 Alice 334.1024 Alice@gmail.com 515203

Tuple 2 2 Bob 128.6427 Bob@hotmail.com 138667

Tuple 3 3 Casey 305.1839 Casey@livemail.tw 152470

…

Tuple n

Schemes• Relational Databases Watermarking for textual and

numerical data– Zhang et al., MEC2011, China, 2011.

• DCT Transform based Relational Database Robust Watermarking Algorithm– Song et al., ISDPE2010, USA, 2010.

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Relational Databases Watermarking for textual and numerical data

2011 International Conference on Mechatronic Science, Electric Engineering and Computer

Author: Lizhong Zhang, Wei Gao, Nan Jiang, Liqiu Zhang and Yan Zhang

Notations and Parameters

Parameter Description

N N is a natural number

e Number of groups in the relation

Key User’s secret key

ri.p Primary key of the ith tuple in relation or in group

Hi Tuple Hash of the ith tuple

ri.mod The remainder of the ith tuple

ri.Aj the jth attribute value of the ith tuple in the relation

Lt Watermark tag location of textual attributes

Ln Watermark tag location of numerical attributes

Number of candidate bits to be modified

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Watermark embedding algorithm• Tuples selection.

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𝐻 𝑖= h𝐻𝑎𝑠 (𝐾𝑒𝑦 ,𝑟 𝑖 .𝑝 )

𝑟 𝑖 .𝑚𝑜𝑑=𝐻 𝑖𝑚𝑜𝑑𝑒𝑟 𝑖 .𝑚𝑜𝑑<

𝑒𝑁Condition:

Primary key Attribute1 Attribute2 Attribute3 Attribute4

Tuple 1

Tuple 2

Tuple 3

…

Tuple n

40,000

Watermark embedding algorithm• Watermark insertion

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Primary key Attribute1 Attribute2 Attribute3 Attribute4

Tuple 235 235 Paul 212.751 akaily@livemail.tw 99700

Set: Hi=Hash(Key, 235)=155, e=37, =5, N=2, Watermark bit =1

Textual attribute:

Numerical attribute: 𝐿𝑡 𝑖 , 𝑗=𝐻 𝑖𝑚𝑜𝑑 h𝑙𝑒𝑛𝑔𝑡 (𝑟 𝑖 . 𝐴 𝑗) 𝐿𝑛𝑖 , 𝑗=𝐻 𝑖𝑚𝑜𝑑𝜀

If Watermark bit =1 then Insert #13(Carriage return character) at location Lti,j

Else Insert #10(Linefeed character) at location Lti,j

If Lni,j digits mod 2 ≠ watermark bit then Lni,j digits 1

155 mod 5 = 0

1

155 mod 4 = 3

Watermark extracting algorithm• Tuples selection• Watermark extraction

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𝐿𝑡 ′𝑖 , 𝑗=𝐻 ′ 𝑖𝑚𝑜𝑑 ( h𝑙𝑒𝑛𝑔𝑡 (𝑟 ′𝑖 . 𝐴 ′ 𝑗 )−1)

Primary key Attribute1 Attribute2 Attribute3 Attribute4

Tuple 235 235 P aul 212.751 akaily@livemail.tw 99701

Textual attribute:

Numerical attribute: 𝐿𝑛 ′ 𝑖 , 𝑗=𝐻 ′𝑖𝑚𝑜𝑑 𝜀Watermark bit = Lni,j digits mod 2If #13 at location Lti,j then

Watermark bit =1 If #10 at location Lti,j then Watermark bit =0

Experimental results• Subset Addition Attack

– Watermark detected ratio 99.5%• Subset Alteration Attack

– Watermark detected ratio 99.5% even if 70% of the tuples of the database are modified

• Subset Deletion Attack– Watermark detected ratio 95% even if 70% of the tuples

are deleted.

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DCT Transform based Relational Database Robust Watermarking Algorithm

2010 Second International Symposium on Data, Privacy, and E-Commerce

Author: Song Yige, Liu Weidong, Song Jiaxing and Wong Ming Sze Angela

Notations and Parameters

Parameter Descriptionthe primary key of the ith tuple in the relation or in a group

user’s secret key

tuple hash of the ith tuple

tuple group number of the ith tuple

g number of groups in the relation after divide

s number of attributes allowed tag in the relation

watermark tag attribute location of the ith tuple

C The medium frequency coefficient in DCT

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Watermark embedding algorithm• Tuples selection

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𝑟 𝑖 . h h𝑎𝑠 𝑘𝑒𝑦= h𝐻𝑎𝑠 (𝐾𝑒𝑦 ,𝑟 𝑖 .𝑃)

𝑟 𝑖 . h h𝑎𝑠 𝑚𝑜𝑑=𝑟 𝑖 . h h𝑎𝑠 𝑘𝑒𝑦𝑚𝑜𝑑𝑔𝑟 𝑖 . 𝑙𝑜𝑐𝑎𝑡𝑖𝑜𝑛=𝑙𝑜𝑐𝑎𝑡𝑖𝑜𝑛 (𝑟 𝑖 . h h𝑎𝑠 𝑘𝑒𝑦 ,𝑘 𝑗 )𝑚𝑜𝑑𝑠

Primary key Attribute1 Attribute2 Attribute3 Attribute4

Tuple 1

Tuple 2

Tuple 3

…

Tuple n

581,012

Watermark embedding algorithm• DCT transform - two-dimensional DCT• Watermark insertion

– Select medium frequency coefficient as C

• Inverse DCT transform• Update database

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If (Watermark bit =1 && C > 0 ) or (Watermark bit =0 && C < 0 ) then C = C

Extracting phase:

if C > 0 then Watermark bit = 0else if C < 0 then Watermark bit = 1

Experimental results• Subset Addition Attack

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Original watermark and extracted watermark after tuple deletion attack

Experimental results• Subset Alteration Attack

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Original watermark and extracted watermark after tuple deletion attack

Experimental results• Subset Deletion Attack

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Original watermark and extracted watermark after tuple deletion attack

Discussion• Practicality• Affect data analysis result• Affect data mining result• Effect of computing time for big data

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