A secure distributed single-login authentication system comprises a client and a server. The client collects a user name and password from a user and tests that user name and password at a variety of potential authentication servers to check where the login is valid. It combines the password with a time varying salt and a service specific seed in a message digesting hash and generates a first hash value. The client sends the hash value along with the user name and the time varying salt to a currently selected server. The server extracts the user name and looks up an entry under the user name from the selected server's database. If an entry is found, it retrieves the password and performs the same hash function on the combination of the user name, the service specific seed, and the retrieved password to generate a second hash value. Then, it compares two hash values. If these two values match, the user is authenticated. In this way, the system never sufficiently reveals the password to authentication agents that might abuse the information.