Watermarking relational databases using optimization based techniques
A study for Relational Database watermarking scheme
description
Transcript of A study for Relational Database watermarking scheme
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 [email protected] 515203
Tuple 2 2 Bob 128.6427 [email protected] 138667
Tuple 3 3 Casey 305.1839 [email protected] 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 [email protected] 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 [email protected] 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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