PublicKeyCredentialRequestOptions.extensions

Secure context
This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

extensions, an optional property of the PublicKeyCredentialRequestOptions dictionary, is an object providing the client extensions and their input values.

Extensions are values requesting additional processing by the client and by the authenticator. For instance, extensions may be used for:

backward compatibility with the legacy FIDO JS API,
knowing the user verification process,
etc.

Note: An analogous option exists for the creation operation (navigators.credentials.create()), see PublicKeyCredentialCreationOptions.extensions.

Syntax

extensions = publicKeyCredentialRequestOptions.extensions

Value

An object with various keys and values.

Here is the current (as of March 2019) list of potential extensions which may be used during the registration operation.

Warning! As of June 2020, only appid is supported by Chrome and Edge. Firefox does not seem to support any extension. Also Chrome doesn't plan to support any other extension in future

Extension identifier	Type	Description
`appid`	`USVString`	FIDO appID. An appID which was used with legacy FIDO JS APIs to identify the current relying party.
`txAuthSimple`	`USVString`	Simple transaction authorization. This text is displayed on a prompt of the authenticator before verifying the user or testing their presence. The client outputs a `USVString` which is the text as it was displayed (line breaks may have been added).
`txAuthGeneric`	An object with two properties: `contentType` (`USVString`) `content` (`ArrayBuffer`)	Generic transaction authorization. This is used to display an image or some non-textual content on the authenticator before verifying the user or testing their presence. The `contentType` gives the MIME type of the resource to be displayed while `content` gives its actual content. The client outputs the hash of the content which was displayed (hashing with the same algorithm which is used for the signature).
`uvi`	Boolean	User verification index. If `true`, the client outputs an `ArrayBuffer` which contains a value uniquely identifying a user verification data record. In other words, this may be used server side to check if the current operation is based on the same biometric data that the previous authentication.
`loc`	Boolean	Location. If `true`, the client outputs a `Coordinates` object representing the geolocation of the authenticator.
`uvm`	Boolean	User verification method. If `true`, the client outputs an array of arrays with 3 values containing information about how the user was verified (e.g. fingerprint, pin, pattern), how the key is protected, how the matcher (tool used for the authentication operation) is protected.

Note: Extensions are optional and different browsers may recognize different extensions. All extensions are optional for the client to process them: if a browser does not know a given extension, that will not cause any failure, the extension simply will not be processed.

Examples

var options = {
  extensions: {
    uvm: true,
    loc: false,
    txAuthSimple: "Could you please verify yourself?"
  },
  challenge: new Uint8Array([/* bytes sent from the server */])
};

navigator.credentials.get({ "publicKey": options })
    .then(function (credentialInfoAssertion) {
    // send assertion response back to the server
    // to proceed with the control of the credential
}).catch(function (err) {
     console.error(err);
});

Specifications

Specification	Status	Comment
Web Authentication: An API for accessing Public Key Credentials Level 1 The definition of 'extensions' in that specification.	Recommendation	Initial definition.

Browser compatibility

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`extensions` Experimental	Chrome Full support 67	Edge Full support ≤79	Firefox Full support 60	IE ?	Opera Full support Yes	Safari Full support 13	WebView Android Full support 67	Chrome Android Full support 67	Firefox Android ?	Opera Android Full support Yes	Safari iOS Full support 13.3	Samsung Internet Android No support No

Legend

Full support: Full support
No support: No support
Compatibility unknown: Compatibility unknown
Experimental. Expect behavior to change in the future.: Experimental. Expect behavior to change in the future.