A computing system, method, and computer program product provide cryptographic isolation between a client device and a server computer for providing a network service to the client device. The computing system stores encrypted user authentication data of the client device and its user, and encrypted service authorization data of the server computer in such a way that neither the client device nor the server computer can obtain information about the other. Upon subsequent receipt in the computing system of purported user authentication data and a request to access the network service, the computing system encrypts the purported authentication data and compares it against the stored, encrypted data. Only when these encrypted data match is the computing system able to decrypt the service authorization data and provide it to the server computer to gain access to the network service.