Blind signature protocol based on difficulty of simultaneous solving two difficult problems

In fact, most of the developed blind signatures are based on a single difficult problem.If one finds a solution to this problem then the blind schemes are breakable.The probability of such event is sufficiently small and the value of the probability P should be taken into account while estimating the protocol security, additionally to the difficulty W of the best known attack on the protocol. The ratio W/P can be defined as integrated security parameter. Therefore reducing the value P leads to increasing the integrated security parameter. In this paper, we propose the blind signature protocol breaking of which requires simultaneous solving two independent difficult problems, factorization and discrete logarithm. Since these two problems are independent, the value P is significantly reduced, i.e. the proposed protocol has higher integrated security than the known blind signature protocols.