12850 is neither civil nor aero related, at least according to the UDXF logs. The North Korean Diplomatic service runs a sometimes-active HF network at ARQ/600 baud; as that is one of the speeds HFDL can use, I can easily see how it could be mistaken for that.
Enigma is the name of a sub-group within the UDXF that tracks (basically) signals that can be decoded but not read. Often it's assumed that it can be military, intelligence services, diplomatics and other applications, but it's never really sure as to what the signal is sending
There are several very expensive decoding apps that have analysis tools generally not available to the average hobbyist. These include Hoka Code 300-32, Krypto 500 and 1000 (no, not Superman's dog), and Procitec's go2decode and go2monitor. But even these won't break hard encryption
My first thought on that 5531 frequency might be a high speed PACTOR or STANAG mode, but that's pure guesswork. Mike