In some implementations, a server device may receive, from a first device, a credential and a request to access a resource. The server device may transmit, to a second device associated with the credential, an image that includes a first symbol composed of a set of elements. The server device may receive, from the first device, information associated with a second symbol formed via user interaction with a user interface of the first device. The second symbol may be formed by dragging elements, presented via the user interface, to an area of the user interface in which the second symbol is to be formed, or drawing elements in the area of the user interface in which the second symbol is to be formed. The server device may grant or denying access to the resource based on the first symbol and the information associated with the second symbol.