An identity authority computing device having a processor in communication with a database is described herein. The database stores a plurality of persistent user identifiers associated with a plurality of users. The processor is programmed to receive a service request over a public network, the service request including a service provider identifier and a single-use token value associated with one of the users. The processor is also programmed to determine at least one persistent user identifier associated in the database with the token value, and generate an updated service request including the at least one persistent user identifier. The processor further is programmed to generate an encrypted service request using a public encryption key associated with the service provider identifier, and transmit the encrypted service request to a service provider computing device associated with the service provider identifier.