Embodiments described herein relate to securing the privacy of knowledge used to authenticate a user (i.e., Proof of Knowledge (PoK) test(s)). In some embodiments, a client device is operable to receive a first encryption key and encrypted test(s) from a PoK server. The client device also receives a second encryption key from a Relying Party (RP) server. The client device can decrypt the encrypted test(s) by using the first encryption key and the second encryption key to thereby render decrypted test(s). The client device is further operable to obtain answer(s) for the decrypted test(s), send a communication to the PoK server based on the answer(s), and receive a communication from the RP server that authorizes a user of the client device to access service(s) administered by the RP server.