Many D-Link routers such as DIR-2660 are great platforms for OpenWRT. You can easily replace the default firmware with OpenWRT using its recovery GUI.
However, for whatever reason you need to revert the router back to its original firmware, it isn't that straightforward. It seems recent D-Link firmware is encrypted but the recovery GUI can only take unencrypted firmware. This means, the conversion is a one way trip.
Luckily, someone has developed a utility called "dlink-decrypt" overcoming this.
https://github.com/0xricksanchez/dlink-decrypt
As its name suggested, it decrypts the original firmware which can then used by the recovery GUI to revert the device back to its original setup.
