Cryptanalysis of the blind signatures based on the discrete logarithm problem

In a recent paper (see L. Harn, ibid., vol.31, no.14, pp.1136, 1995), Harn claims that certain signature schemes are not true blind signatures. In this comment we prove that this claim is incorrect. Harn´s attempt to cryptanalyse the schemes is incorrect, since the proposed relationship, which is used to trace the signature by the signer, is an invariant that is satisfied by any two pairs of signed messages