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) {


Web Authentication: An API for accessing Public Key Credentials - Level 3 (Web Authentication)
# dom-publickeycredentialrequestoptions-challenge

Browser compatibility

BCD tables only load in the browser

See also