Secure watermarking scheme against watermark attacks in the encrypted domain Source: Journal of Visual Communication and Image Representation, Vol.30, pp.125-135,2015. Authors: Jianting Guo, Peijia Zheng and Jiwu Huang. Speaker: Chin Hao Chuan Date: 03/09

Outline Related Work Proposed Scheme Experimental Results Conclusions Paillier homomorphic encryption Proposed Scheme Experimental Results Conclusions

Related Work-PHE p,q N=p∗q γ=𝑙𝑐𝑚 𝑝−1,𝑞−1 Public key :(N, g) 𝑔 𝑙𝑐𝑚 : Least common multiple p,q N=p∗q γ=𝑙𝑐𝑚 𝑝−1,𝑞−1 Public key :(N, g) 𝑔 gcd L 𝑔 𝛾 𝑚𝑜𝑑 𝑁 2 ,𝑁 =1 𝐿 𝑥 = 𝑥−1 𝑁 Private key:(p, q,γ) 𝑚= 𝐿( 𝑐 𝛾 𝑚𝑜𝑑 𝑁 2 ) 𝐿( 𝑔 𝛾 𝑚𝑜𝑑 𝑁 2 )

Proposed Scheme LL LH HL HH DWT

Proposed Scheme 𝐵 1 LL 𝐵 2 DCT 𝐵 1 𝑇 1 𝐵 2 𝑇 2 428 403 432 429 425 408 412 416 409 438 405 407 415 431 1 2 1 2 1 2 1 2 428 432 403 404 429 433 425 408 438 412 419 416 402 409 414 421 405 413 407 436 415 411 431 430 401 400 420 427 437 426 𝐵 1 432 404 433 429 438 419 402 414 421 413 436 428 411 405 LL 𝐵 2 428 403 432 429 425 408 412 416 409 438 405 407 415 431 1681 4 9 8 -6 -8 7 11 21 -11 12 24 -3 1 -15 -16 DCT 𝐵 1 𝑇 1 432 404 433 429 438 419 402 414 421 413 436 428 411 405 1683 7 11 1 15 -3 -4 13 16 17 5 -28 14 𝐵 2 𝑇 2

Proposed Scheme 𝐾𝑒𝑦 2 :0101 𝑋 2 = 𝑋 1 +2 𝑖𝑓 𝑤 𝑖 =1 𝑋 1 −2 𝑖𝑓 𝑤 𝑖 =0 1681 4 9 8 -6 -8 7 11 21 -11 12 24 -3 1 -15 -16 𝑋 2 = 𝑋 1 +2 𝑖𝑓 𝑤 𝑖 =1 𝑋 1 −2 𝑖𝑓 𝑤 𝑖 =0 𝑇 1 𝑋′ 2 =7+2=9 1683 7 11 1 15 -3 -4 13 16 17 5 -28 14 𝑋′ 2 =−3−2=−5 1683 7 11 1 15 -3 9 13 -4 16 17 -5 -28 14 𝑇 2 1 𝐾𝑒𝑦 1 436 399 427 437 433 438 419 406 411 421 413 432 424 416 410 𝑊

Proposed Scheme-extraction 428 403 432 429 425 408 412 416 409 438 405 407 415 431 1681 4 9 8 -6 -8 7 11 21 -11 12 24 -3 1 -15 -16 DCT 𝐵′ 1 𝑇′ 1 436 399 427 437 433 438 419 406 411 421 413 432 424 416 410 1683 7 11 1 15 -3 9 13 -4 16 17 -5 -28 14 𝐵′ 2 𝑇′ 2 𝑋′ 2 − 𝑋 ′ 1 >0 ⇒ 𝑤 𝑖 =1 𝑋′ 2 − 𝑋 ′ 1 <0 ⇒ 𝑤 𝑖 =0 1 𝐾𝑒𝑦 2 :0101 9−7=2>0 −5− −3 =−2<0 𝑊

Experimental Results (a) noise attack; (b) cropping attack;

Experimental Results (c) BDCTlm; (d) DCTlm; (e) DWTll; (f) JPEG-90; [11] T. Bianchi, A. Piva, M. Barni, Encrypted domain DCT based on homomorphic cryptosystems, EURASIP J. Inform. Secur. (2009).

Experimental Results

Conclusions By combining the encrypted domain DWT and DCT, the performance of the watermarking scheme has been improved. The visual quality and the robustness of the scheme are satisfactory.