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 /spl alpha/ large prime number. The Harn signature scheme is modified to give it the same degree of security as was originally claimed.