Security Level 4 in Bluetooth LE connection

  • Responder: Always corresponds to the Link Layer Slave and the GAP peripheral.
  • Level 2: Unauthenticated pairing with encryption
  • Level 3: Authenticated pairing with encryption
  • Level 4: Authenticated LE Secure Connections pairing with encryption
  • Passkey Entry: The Passkey Entry is primarily intended for the case that one device has a keyboard, but no display unit and the other device has at least a display unit, for example, a PC and a BLE keyboard scenario. The user is shown a six-digit number (from “000000” to “999999”) on the device with a display and then is asked to enter the number on the other device. If the value entered on the second device is correct, the pairing is successful.
  • Just Works: This model is primarily intended for the most constrained devices in I/O. The Just Works association model uses the Numeric Comparison protocol, but the user is never shown a number, and the application may ask the user to accept the connection. This method doesn’t offer protection against a Man in the Middle (MITM) attack, but it provides the same protection level against passive eavesdropping as the Numeric Comparison.
  • AT+ENTERPASSKEY for entering the 6-digit passkey to continue the pairing request.
  • AT+SECLVL for setting or querying minimum security level used when connected to other devices.
  • AT+NUMCOMPA accepts a numeric comparison authentication request or enables/disabling auto-accepting numeric comparisons.
  • AT+GAPADDRTYPE Sets or queries what address type the dongle will use. Changing address type cannot be done while advertising or while connected to other devices. Read more at



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The BleuIO is Bluetooth low energy solution that can be used to create new BLE 5.0 applications in the fastest and easiest way.