Abstract: Techniques are provided for user authentication using a location assurance based on a location indicator modified by a shared secret. One method comprises obtaining a shared secret; initiating a challenge in connection with an authentication request by a client from a given location to access a protected resource, wherein the challenge comprises a location indicator selected for the given location; processing a response submitted by the client in response to the challenge, wherein the response comprises the location indicator for the given location modified by the client with the shared secret, and wherein the processing comprises evaluating the response submitted by the client relative to the location indicator selected by the authentication server; and resolving the authentication request based on the evaluating. The client modification of the selected location indicator with the shared secret comprises, for example, decrypting, filtering and/or altering the location indicator based on the shared secret.