Security of digital signature with one-time pair of keys [comment]

Recently, Yi et al. [see ibid., vol. 36, no. 2, p. 130-1 (2000)] proposed a digital signature scheme using a one-time pair of keys that provides the signer with anonymity with respect to the verifier but not to the certification authority. In this comment, we show that Yi et al.´s scheme is insecure against forgery because any malicious attacker can generate valid signatures for any message without knowing the legal user´s secret keys. That is, even the certification authority cannot identify the identity of the real signer. Therefore, Yi et al.´s signature scheme is not secure enough to withstand a forgery attack