Modified Harn signature scheme based on factorising and discrete logarithms

L. Harn (1994) proposed a digital signature scheme which was claimed to be unbreakable if the factorisation and the discrete logarithms are simultaneously unsolvable. The paper shows that `hackers´ can forge the signatures of Harn schemes with high probabilities, if they can solve the discrete logarithms modulo α large prime number. The Harn signature scheme is modified to give it the same degree of security as was originally claimed