End-to-end verifiable multi-factor authentication service
An end-to-end verifiable multi-factor authentication scheme uses an authentication service. An authentication request is received from an organization, the request having been generated at the organization in response to receipt there of an access request from a user. The user has an associated public-private key pair. The organization provides the authentication request together with a first nonce. In response to receiving the authentication request and the first nonce, the authentication service generates a second nonce, and then it send the first and second nonces to the user. Thereafter, the service receives a data string, the data string having been generated by the client applying its private key over the first and second nonces. Using the user's public key, the service attempts to verify that the data string includes the first and second nonces. If it does, the authentication service provides the authentication decision in response to the authentication request, together with a proof that the user approved the authentication request.
1. A method of authenticating a user requesting access to a network-accessible resource, the user associated with a client and having an associated public-private key pair, the key pair comprising a private key, and an associated public key, comprising:
at an authentication service to which the resource is associated:
receiving from the resource an authentication request, the authentication request having been generated at the resource in response to receipt of an access request from the user, the authentication request having associated therewith a first nonce;
in response to receiving the authentication request and the first nonce, generating a second nonce, and sending the first and second nonces to the user;
upon receipt of a data string, the data string having been generated by the client applying the private key over the first and second nonces, determining, using the associated public key, that the data string includes the first and second nonces; and
upon verifying that the data string includes the first and second nonces, providing the resource an authentication decision in response to the authentication request, together with a proof that the user approved the authentication request.
2. The method as described in claim 1 wherein the first nonce and the second nonce are each a cryptographically random-generated one time use token.
3. The method as described in claim 1 wherein inclusion of the first nonce cryptographically binds the authentication request to the proof.
4. The method as described in claim 3 wherein inclusion of the second nonce provides an independent authentication proof for the authentication service.
5. The method as described in claim 1 wherein the data string is a signature generated by applying the private key over a concatenation of the first nonce and the second nonce.
6. The method as described in claim 1 wherein the authentication service is associated with an overlay network.
7. The method as described in claim 1 wherein the authentication service workflow is associated with an auxiliary method of multi-factor authentication.
8. The method as described in claim 7 wherein the auxiliary method of multi-factor authentication is one of: push, push TOTP (time-based one-time passcode), phish-proof push, U2F, WebAuthn, hardware OTP (one time passcode), external TOTP, SMS OTP, email OTP, client-less push by SMS, client-less push by email, phone call, and bypass codes.
9. The method as described in claim 1 wherein the first nonce is generated by the network resource.
10. An apparatus configured as an authentication service, comprising:
a processor;
computer memory holding computer program instructions executed by the processor, the computer program instructions including program code operative to authenticate a user requesting access to a network-accessible resource, the user associated with a client and having an associated public-private key pair, the key pair comprising a private key, and an associated public key, the program code configured to:
receive from the resource an authentication request, the authentication request having been generated at the resource in response to receipt of an access request from the user, the authentication request having associated therewith a first nonce;
in response to receiving the authentication request and the first nonce, generate a second nonce, and send the first and second nonces to the user;
upon receipt of a data string, the data string having been generated by the client applying the private key over the first and second nonces, determine, using the associated public key, that the data string includes the first and second nonces; and
upon verifying that the data string includes the first and second nonces, provide the resource an authentication decision in response to the authentication request, together with a proof that the user approved the authentication request.
11. The apparatus as described in claim 10 wherein the first nonce and the second nonce are each a cryptographically random-generated one time use token.
12. The apparatus as described in claim 10 wherein inclusion of the first nonce cryptographically binds the authentication request to the proof.
13. The apparatus as described in claim 12 wherein inclusion of the second nonce provides an independent authentication proof for the authentication service.
14. A computer program product in a non-transitory computer-readable medium comprising program code executable in hardware on a computing system configured as an authentication service, the program code operative to authenticate a user requesting access to a network-accessible resource, the user associated with a client and having an associated public-private key pair, the key pair comprising a private key, and an associated public key, the program code configured to:
receive from the resource an authentication request, the authentication request having been generated at the resource in response to receipt of an access request from the user, the authentication request having associated therewith a first nonce;
in response to receiving the authentication request and the first nonce, generate a second nonce, and send the first and second nonces to the user;
upon receipt of a data string, the data string having been generated by the client applying the private key over the first and second nonces, determine, using the associated public key, that the data string includes the first and second nonces; and
upon verifying that the data string includes the first and second nonces, provide the resource an authentication decision in response to the authentication request, together with a proof that the user approved the authentication request.
15. The computer program product as described in claim 14 wherein the first nonce and the second nonce are each a cryptographically random-generated one time use token.
16. The computer program product as described in claim 14 wherein inclusion of the first nonce cryptographically binds the authentication request to the proof.
17. The computer program product as described in claim 16 wherein inclusion of the second nonce provides an independent authentication proof for the authentication service.