Out-of-band authentication based on secure channel to trusted execution environment on client device

A computer-implemented method executed by one or more processors of a computing device that supports a client-side role in out-of-band authentication, the method comprising:

• obtaining an authentication application within a memory of a computing device;
• and
• executing, by the computing device, the authentication application within a client execution environment of the computing device, the authentication application when executed being configured to perform operations comprising:
• establishing one or more secure sessions with a trusted execution environment of the computing device over which the authentication application communicates with the trusted execution environment, the trusted execution environment comprising a secure memory not accessible from the client execution environment other than via secure sessions;
• requesting in a first request, over a first one of the secure sessions, establishment of a set of credentials corresponding to a given user of the computing device within the secure memory by a co-processor of the trusted execution environment, the co-processor being a different processor from a central processing unit of the computing device;
• obtaining, over a second one of the secure sessions after at least some credentials in the set of credentials corresponding to the given user are established, first data comprising & respective representations of each of the at least some credentials in the set of credentials, respective representations corresponding to the given user, first signed data, and a signature key of the trusted execution environment, the signature key being a public key of a public/private cryptographic key pair having a private key retained by the trusted execution environment;
• determining whether the co-processor of the trusted execution environment generated all of the representations, the determination being responsive to the signature key of the trusted execution environment to which the representations correspond;
• in response to the determination, sending, via a network, the first data and the first signed data to a server system;
• accessing, within the memory other than the secure memory on the computing device, information from a notification requesting authentication of the given user of the computing device, the notification being received after sending the first data and the first signed data to the server system, and the notification being stored within the memory other than the secure memory on the computing device, the memory other than the secure memory on the computing device having a different memory address bus relative to the secure memory;
• in response to the notification, requesting in a second request, over a third one of the secure sessions, second data comprising the representation of a given credential from the at least some credentials in the set of credentials and second signed data, wherein the second data and the second signed data are received dependent upon authentication of the given user by the co-processor of the trusted execution environment, and wherein the authentication of the given user is based on the given credential stored within the secure memory by the co-processor;
• and
• sending the second data and the second signed data to the server system.

A computer-implemented method, executed by a server-side computing system that supports a client-side role in out-of-band authentication based on a secure channel to a trusted execution environment on a first device different from a second device requesting access to a secure asset, the method comprising:

• registering the first device having a trusted execution environment, the registering comprising:
• establishing a user record associated with a user permitted to access the secure asset, the user record comprising a user identifier associated with the user;
• and
• establishing, in association with the user record, a device record for the first device in response to receiving, from the first device, a set of representations corresponding to a set of credentials stored within the trusted execution environment on the first device, device information including a device identifier of the first device, and a signature key corresponding to the trusted execution environment;
• receiving information corresponding to an attempt to access the secure asset from the second device, the received information comprising the user identifier and device information of the second device;
• identifying the user record associated with the user based on the user identifier;
• selecting the device record for the first device associated with the user record, the device record for the first device being selected based on the first device having a trusted execution environment;
• transmitting a notification to the first device based on the device identifier stored within the device record for the first device, the notification requesting approval of the attempt to access the secure asset;
• receiving, from the first device, a response to the notification the response including data comprising a representation of a credential, the representation in the set of representations corresponding to the set of credentials stored within the trusted execution environment on the first device and signed data;
• determining an authentication result by verifying the representation of the credential received in the response to the notification, wherein verifying the representation comprises matching the representation with the stored representation in the device record of the first device and verifying that the data was generated by the trusted execution environment based on the data, the signed data, and the signature key corresponding to the trusted execution environment;
• and
• transmitting the authentication result to grant the access attempt by the second device.