On Tuesday, January 5, 2016 at 12:10:14 PM UTC-8, wrote:
On Tuesday, January 5, 2016 at 12:14:30 PM UTC-5, jfitch wrote:
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."


From Flarm card:
Stealth Mode
The data FLARM(R)
receives from other is available at the serial
port to external devices like PDA's or graphical displays which
can thus display the nearby environment in detail. While this
information is useful for you, you might not want your
competitors to make use of this information, and others might
have the similar asymmetrical preferences. With the stealth
mode (named 'Privacy' before) in FLARM(R)
, you can choose
the trade-off acceptable for you between two modes:
* 'Stealth Mode' unchecked: you have full access to the data
you receive from others with Stealth Mode disabled and,
and others have full access to the data you send about
yourself if they have Stealth Mode disabled, or
* 'Stealth Mode' checked: you have limited access to the
data you receive from others and, and others have limited
access to the data you send about yourself independent of
their Stealth Mode setting.

I interpret this as saying info out to others is limited in Stealth mode which is the basis for my comment. I originally thought filtering was only on the receiving side which as you said, but this information contradicts that. I think I stand by my comment.
UH

The sending unit must always send all the data, and the receiving unit receive it. Otherwise how will they determine if a conflict exists? Stealth only decides if the data will be forwarded to the serial port out for display, otherwise it is held sequestered in the box. I don't see anything in what you quoted that contradicts this. However someone knows, and could clarify this finally.