By studying Shamir’s secret sharing scheme, this paper proposes an authentication scheme with intrusion-tolerant feature that stores user password data in distributed shared servers. Valid authentication services are continuously available even though a minority of shared servers are compromised, and reconstructing original password data is not demanded during authentication processes. Through this scheme, the availability and security of authentication system will be enhanced. By studying Shamir’s secret sharing scheme, this paper proposes an authentication scheme with intrusion-tolerant feature that stores user password data in distributed shared servers. Valid authentication services are continuously available even though a minority of shared servers are compromised, and reconstructing original password data is not demanded during authentication processes. Through this scheme, the availability and security of authentication system will be enhanced.