Secure Hybrid Mode-Based Cryptosystem
O. · American Journal of Applied Sciences · 2012
Problem statement: A cryptosystem provides two parties; a sender and a receiver to communicate interactively via an insecure channel in which, the sender is able to send any confidential message, document or data in a disguised form to the intended receiver.Upon receiving the disguised message, the receiver converts it to the intelligible message using his secret key.The security of the existing cryptosystems was based on a single hard problem such as factorization, discrete logarithm, quadratic residue, or elliptic curve discrete logarithm.Although these schemes appear secure, one day in a near future they may be broken if one finds a solution of a single hard problem.Approach: To overcome the disadvantage of using a single hard problem, we developed a secure hybrid mode-based cryptosystem based on the two well-known hard problems; factoring and discrete logarithm.We inject the element of the hard problems into our encrypting and decrypting equations respectively in such a way that the former equation depends on two public keys whereas the latter depends on two corresponding secret keys.Results: The new cryptosystem is shown heuristically secure against various algebraic attacks.The efficiency analysis confirms that our scheme only needs 3T exp +T hash time complexity for encryption and 2T exp time complexity for decryption and this magnitude of complexity is considered minimal for multiple hard problems-like cryptosystems.Conclusion: The newly developed hybrid mode based-cryptosystem provides greater security level than that schemes based on a single hard problem.The enemy or adversary has to solve the two problems simultaneously which is unlikely to happen in order to read any secret message.