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Private-Key Cryptosystem

Among numerous possible {k,n} threshold configurations, the simplest case is constituted by {2,2} schemes. By reducing the number of shares to only two pieces, a private-key cryptosystem is obtained, as each of the two generated shares can be used as the decryption key for the other share.
 

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  Secret gray-scale image   Share 1   Share 2   Decrypted image  

Unlike the traditional secret sharing solutions which encrypt each secret pixel into a block of share pixels, a cost-effective variant of the image secret sharing framework with the perfect reconstruction property reduces the encryption and decryption operations from the block level to the pixel level. The solution operates on the decomposed bit-levels of the secret image. Each decomposed bit of the original pixels is encrypted into a single output bit for each of the two shares. In this way, the produced shares have the same spatial resolution as that of the original image, thus allowing significant computational and memory savings and efficient transmission of the shares in public networks.
 

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  Secret color image   Share 1   Share 2   Decrypted image  

References:

 
bullet R. Lukac and K.N. Plataniotis, Secure Color Imaging. In Color Image Processing: Methods and Applications, (eds.) R. Lukac and K.N. Plataniotis, CRC Press / Taylor & Francis, pp. 185-202, October 2006. ISBN 0-8493-9774-X
bulletR. Lukac, K.N. Plataniotis, and C.N. Yang, Image Secret Sharing. In Encyclopedia of Multimedia, (ed.) B. Furth, Springer-Verlag, pp. 328-335, January 2006. Including short articles: Compression in Image Secret Sharing (pp. 86-87), Halftoning-Based Visual Secret Sharing (pp. 363-364), Image Watermarking Using Visual Cryptography (pp. 337-338), Private-Key Cryptosystem (pp. 712-714), Threshold Schemes with Minimum Pixel Expansion (pp. 849-850), Visual Cryptography (pp. 950-951). ISBN 0-387-24395-X
bulletR. Lukac and K.N. Plataniotis, "A Cost-Effective Encryption Scheme for Color Images," Real-Time Imaging, Special Issue on Multi-Dimensional Image Processing, vol. 11, no. 5-6, pp. 454-464, October-December 2005.
bulletR. Lukac and K.N. Plataniotis, "Digital Image Indexing Using Secret Sharing Schemes: A Unified Framework for Single-Sensor Consumer Electronics," IEEE Transactions on Consumer Electronics, vol. 51, no. 3, pp. 908-916, August 2005.

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Last update: 10/15/06

2006 Rastislav Lukac