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

The challenge property of the PublicKeyCredentialCreationOptions 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, using its private key, and must be sent back for verification to the server as part of AuthenticatorAttestationResponse.attestationObject.

Note: When the credential is retrieved with a navigator.credentials.get() call, the signature of the challenge is contained in AuthenticatorAssertionResponse.signature.

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


challenge = publicKeyCredentialCreationOptions.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 publicKey = {
  challenge: new Uint8Array(26) /* this actually is given from the server */,
  rp: {
    name: "Example CORP",
    id  : ""
  user: {
    id: new Uint8Array(26), /* To be changed for each user */
    name: "",
    displayName: "John Doe",
  pubKeyCredParams: [
      type: "public-key",
      alg: -7

navigator.credentials.create({ publicKey })
  .then(function (newCredentialInfo) {
    // send attestation response and client extensions
    // to the server to proceed with the registration
    // 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

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Chrome Full support 67Edge Full support ≤79Firefox Full support 60IE No support NoOpera Full support 54Safari Full support 13WebView Android No support NoChrome Android Full support 67Firefox Android ? Opera Android Full support 48Safari 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