{
    "version": "U2F_V2",
    "appId": "testApp.com",
    "challenge": "MYvX-7uq2tyd3XO2nl_eNiKbCeETbotZrMFQeRTTl5k",
    "type": "u2f_sign_request",
    "registeredKeys": [
        {
            "version": "U2F_V2",
            "keyHandle": "Ym9ndXNfMTQ2NTU1NjYzNTQ0Nw"
        }
    ]
}