A New Visual Public-Key Cryptosystem Based On Non-Expansion Technique And Boolean Operations
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Date
2011
Authors
Jaafar, Abdullah Mohammed Abdo Ali
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Journal ISSN
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Publisher
Universiti Sains Malaysia
Abstract
Many public-key cryptosystems are used in our daily lives to attain privacy, authenticity, integrity and non-repudiation. However, most of the existing public-key algorithms are based on complex mathematical computations. Until recently, building a highly secured public-key cryptosystem without utilizing complex computations has been a serious challenge, making it necessary for investigations to develop new cryptography methods. Visual cryptography is special because the scheme requires visual inspection or the equivalence of simple Boolean computation and therefore, does not require complex computations. The basic design of visual cryptography exploits the human visual system, to recover secret images. Moreover, the visual inspection process could be carried out very easily by humans, but hard for the computer to imitate. Indirectly, such scheme adds extra protection to the visual scheme against brute-force search on the visual secret key. However, visual cryptography currently exists only for secret-key cryptography. Therefore, in the current study, alternative public-key primitives are proposed, based on non-expansion visual cryptography and Boolean operations. The proposed visual cryptosystem include: visual key exchange protocol, visual digital signature protocol and visual zero-knowledge proof of identity protocol. The security of the proposed visual public-key protocols is assured by the K-SAT NP-hard problem and non-solvable of the non-invertible matrix problem. Security analyses showed that the proposed visual public-key cryptosystem is secure, especially when used with large sizes of shadow images (visual shares). The time required to brute-force the secret
values (visual secret keys) increased exponentially with the increase in the size of shadow images. The wide potential use, specific niche on visual applications, simplicity and ease of implementation of shadow images, therefore makes the proposed visual public-key cryptosystem a suitable alternative to the classical public-key cryptosystems that are currently in use today.
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Keywords
A new visual public-key cryptosystem , based on non-expansion technique