In December 2013, Verizon issued an over-the-air (OTA) update for the Samsung Galaxy S III. The 4.3 update, dubbed "ML1" by the XDA community, introduces Samsung KNOX, a sandboxed Android application environment aimed at business and government customers. Coinciding with the KNOX integration are several changes to the device boot loader firmware. Signing policies are now re-enforced on flashing procedures targeting the boot loader, recovery, and kernel partitions. Attempts to flash the device contents will supposedly trigger a newly exposed eFuse, permanently altering certain hardware circuit paths, thereby signaling expiration of the device's warranty.
Due to a desire by some individuals to downgrade to Android version 4.1, and a prevailing belief that this is now impossible, I will describe below steps on how to flash an older signed system ROM onto a 4.3-installed device.
Warning #1: Despite it being possible to downgrade the system and kernel to official version 4.1, it is not believed possible to d