On Tuesday, January 5, 2016 at 6:02:51 AM UTC-8, wrote:
SNIP Negative- it is much harder to ensure that the new mode performs equally for all without hackers turning it wide open again. This would require use of flight displays running programs shown to be compliant.

I don't believe that is correct. All the information on stealth mode (actually named PRIV in the documents) suggests that the implementation is on the receive end. When the PRIV flag is set, the broadcasts contain the same information, but are marked with the PRIV flag, telling the receiver not to forward the information to the serial port for display (regardless of display). Since the receivers are also running Flarm firmware, they respect this flag. The information is there for the hacking today by someone determined enough. All that needs to be done for non-contestants is to allow the receiver to make the decision based on its PRIV flag. If I was not flying in the contest and did not have the PRIV flag set, my receiver would forward the information to the serial port and the display. The vulnerability to cheating and hacking is the same as now. The change to the firmware to do this should be trivial.

From the dataport spec: "The stealth flag indicates whether the own broadcasted data shall be solely used for collision avoidance15, i.e. where not all the received information is forwarded to the serial data-port and therefore is not available to external, graphical displays or PDA's to prevent abuse in competitions."