Comment on “Digital signature with (t, n) shared verification based on discrete logarithms”

For the original article see ibid., vol. 29, no. 24, p. 2094-95 (1993). The digital signature scheme with (r, n) shared verification proposed by Harn in the aforementioned article can be easily forged universally, as shown by Lee and Chang (see ibid., vol. 31, no. 3, p. 176-7, 1995). In the reply of Harn (see ibid., vol. 31, no. 3, p. 177, 1995), two different solutions to overcome this attack were presented. The commenters discuss the first solution and show that the second solution (and related ones) are flawed, because with a simple attack one can forge this scheme and related ones universally. Finally, they propose a simple solution to countermeasure all attacks