Secure USB debugging
Android 4.2.2 introduces a new way of protecting your apps and data on compatible devices — secure USB debugging. When enabled on a device, secure debugging ensures that only host computers authorized by the user can access the internals of a USB-connected device using the ADB tool included in the Android SDK.
Secure debugging is an extension of the ADB protocol that requires hosts to authenticate before accessing any ADB services or commands. At first launch, ADB generates an RSA key pair to uniquely identifies the host. Then, when you connect a device that requires secure debugging, the system displays an authorization dialog such as the one shown below.
The user can allow USB debugging for the host for a single session or can give automatic access for all future sessions. Once a host is authorized, you can execute ADB commands for the device in the normal way. Until the device is authorized, it remains in "offline" state, as listed in the adb devices command.
For developers, the change to USB debugging should be largely transparent. If you've updated your SDK environment to include ADB version 1.0.31 (available with SDK Platform-tools r16.0.1 and higher), all you need to do is connect and authorize your device(s). If your development device appears in "offline" state, you may need to update ADB. To so so, download the latest Platform Tools release through the SDK Manager.
Secure USB debugging is enabled in the Android 4.2.2 update that is now rolling out to Nexus devices across the world. We expect many more devices to enable secure debugging in the months ahead.