A method, computer program product, and system for providing verification processes associated with a commitment-based authentication protocol are described. A request by a user for access to one or more resources is received, and a presentation policy is transmitted to the user indicating required credentials. A commitment to a revocation handle is received, including an indication of an associated Sigma protocol executed by the user. A challenge value selected from a challenge value set associated with the associated Sigma protocol is transmitted to the user. Based on the selected challenge value, a presentation token and a value parameter that is distinct from the presentation token are received from the user. Based on a determination as to whether the presentation token and value parameter are valid in accordance with the associated Sigma protocol, access for the user to the one or more resources is granted to the user or prevented.