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

The challenge property of the PublicKeyCredentialRequestOptions dictionary is a BufferSource used as a cryptographic challenge. This is randomly generated then sent from the relying party's server. This value (among other client data) will be signed by the authenticator's private key and produce AuthenticatorAssertionResponse.signature which should be sent back to the server as part of the response.

Note: When the credential is created with a navigator.credentials.create() call, the signature of the challenge is contained within AuthenticatorAttestationResponse.attestationObject.

Note: A challenge will be at least 16 bytes long.


challenge = publicKeyCredentialRequestOptions.challenge


A BufferSource which is at least 16 bytes long. Contains a cryptographic challenge emitted from the relying party's server which must be signed by the authenticator's private key and sent back (within the response) to the relying party's server for verification.


var options = {
  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) {


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

Browser compatibility

ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Chrome Full support 67Edge Full support ≤79Firefox Full support 60IE ? Opera Full support YesSafari Full support 13WebView Android Full support 67Chrome Android Full support 67Firefox Android ? Opera Android Full support YesSafari iOS Full support 13.3Samsung Internet Android No support No


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.

See also