def yubikey_authenticated?(otp)
      if yubico_identity? && Account.verify_yubico_otp(otp)
        (Account.extract_yubico_identity_from_otp(otp) == yubico_identity)
      else
        false
      end
    end
def yubikey_authenticated?(otp)
      if yubico_identity? && Account.verify_yubico_otp(otp)
        (Account.extract_yubico_identity_from_otp(otp) == yubico_identity)
      else
        false
      end
    end
Is the Yubico OTP valid and belongs to this account?