Text Watermarking,Text watermarking Techniques,Survey text watermarking,
An Efficient and Anonymous Buyer- Seller Watermarking Protocol C. L. Lei, P. L. Yu, P. L. Tsai and...
-
date post
20-Dec-2015 -
Category
Documents
-
view
217 -
download
4
Transcript of An Efficient and Anonymous Buyer- Seller Watermarking Protocol C. L. Lei, P. L. Yu, P. L. Tsai and...
An Efficient and Anonymous Buyer-Seller Watermarking Protocol
C. L. Lei, P. L. Yu, P. L. Tsai and M. H. Chan, IEEE Transactions on Image Processing, VOL. 13, NO. 12, December 2004
Multimedia Security
Outline
• Customer’s Right Problem
• Buyer-Seller Watermarking Protocol
• Unbinding Problem
• The Proposed Watermarking Protocol
• Discussion
Customer’s Right Problem
• In traditional watermarking scenarios, the seller is entitled to the responsibility of generating and inserting digital watermarks. As a result, the seller is granted access to each watermarked copy.
• A malicious seller can easily frame the buyer by releasing corresponding watermarked copy afterwards.
Memon and Wong’s Protocol
B & IDB
SignWCA(EB(W))
W
SignWCA(EB(W))
EB(W’)=P(EB(W))EB(X’)=EB(X+W’)= EB(X)+EB(W’)
X’=DB-1
(EB(X’))
Privacy Homomorphism
Memon and Wong’s Protocol
Memon and Wong’s Protocol
Memon and Wong’s Protocol
Unbinding Problem
• Failure to bind a watermark to a certain piece of content – U’=U+P1(W1), V’=V+P2(W2)
– If Seller gets V’, P2(W2) is available to seller.
– EB(U+P2(W2)) now can be generated
Roles
• S: seller
• B: buyer
• CA: A trusted certification authority, issuing anonymous certificate
• WCA: a trusted watermark certificate authority
• ARB: arbiter
Notations
• (pkI, skI) : a public-private key pair for owner I• (pk*, sk*): a one-time key pair• SignI(M): digital signature of message M signed by I• DskI /EpkI : Decryption and encryption function• X+W: watermarked version of X, + standards for waterm
ark insertion• ARG: common agreement between buyer and seller, ne
gotiated in advance
Registration Protocol
• B first sends a randomly selected pkB to CA. When CA receives pkB,, it generates an anonymous certificate CertCA(pkB) and sends it back to B.
• The registration process can be skipped if anonymity is not a concern
The Proposed Protocol
The Proposed Protocol
X’=X+V
Epk*(X’’)=Epk*(X’+W)=Epk*(X’)+Epk*(W)Store sales records
The Proposed Protocol
The Proposed Protocol
The Proposed Protocol
The Proposed Protocol
The Proposed Protocol
The Proposed Protocol
Identification and Arbitration
SellerArbiter
Y, X’, CertCA(pkB), CertpkB(pk*), ARG, Signpk*(ARG), Epk*(W), Epkwca(W),SignWCA(Epk*(W), pk*, Signpk*(ARG))
WCA
W
CA
Buyer using pk*
Solving Unbinding Problem
• SignWCA(Epk*(W), pk*, Signpk*(ARG)) explicitly binds W to ARG
• By introducing the one-time key pairs, it is impossible for S to fool B.
Accomplishment of Other Goals
• Buyer’s privacy is well protected by using anonymous certificate.
• Only one communication with seller is required for the buyer now
• Trusted third parties are capable of making appropriate adjudications, no cooperation from buyer is required.
• The WCA gets information about the digital content, thus a more robust watermark may be tailored.