Improved public key authentication scheme for non-repudiation

Recently, Peinado proposed a modification on Lee-Hwang-Li's public key authentication scheme. Peinado claimed that the modified scheme achieves non-repudiation of the user's public key. However, we show that a dishonest user can forge his public key via the verification equation. Hence, Peinado's scheme cannot achieve the non-repudiation service, like the previous versions. And then, an improved public key authentication scheme is proposed. Finally, we prove that our improved scheme can provide the non-repudiation service for the user's public key.