[Home](./index.md) > [@digitalpersona/authentication](./authentication.md) > [U2FAuth](./authentication.u2fauth.md) > [authenticate](./authentication.u2fauth.authenticate.md) ## U2FAuth.authenticate() method Authenticates the user using a user's registered U2F token (FIDO token). Signature: ```typescript authenticate(identity: User | JSONWebToken): Promise; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | identity | User | JSONWebToken | a or a JSON Web Token. | Returns: `Promise` a promise to return a JSON Web Token containing a claim (`crd`) showing the fact a U2F was used. To resolve the promise, the user must touch the U2F token when prompted. Will reject if authentication fails or times out. ## Remarks If the `identity` parameter is a user name, a new token will be created. If the `identity` parameter is a JSON Web Token, an updated token will be returned. The user must have a U2F (FIDO) token enrolled in the DigitalPersona server. The user should insert the token and activate it using a touch or pressing a device button. The promise returned by the method will be resolved after the user activates the token, otherwise it will reject with a timeout error.