Updating my plane’s very old GPS data in a very modern way
&gt; The key turned out to be the actual 32-bit GPS “key” and the “encryption” method was laughably simple: use the key as the starting value for CRC-32. To decrypt each byte, subtract from it the lower 8 bits of the current CRC. After the byte is decrypted, update the CRC for it. I am not joking, this is it.<p>[...]<p>&gt; Fun tidbit: you can decrypt the file without knowing whose GPS it was for and what their “key” is. Honeywell engineers were nice enough to leave the decryption key right in the file footer.<p>When reading stories like this, I like to try to figure out whether the developers who designed these things were 1. totally incompetent &#x2F; careless, thinking they&#x27;re actually securing their precious IP, 2. powerless contractors, just dutifully implementing the half-witted attempt at obfuscation some other &quot;architect&quot; designed, or 3. actually true hackers, sympathetic to the cause, deliberately leaving breadcrumbs and vulnerabilities for like minded souls who will later go through the effort to reverse engineer their work.<p>When I&#x27;m in one of my rare optimistic moods, like today, I like to imagine it was #3.