The community does some it’s own checking. The C++ version was partially audited with the response being positive. The auditors even stated that it was of great quality. The rust rewrite has yet to undergo a similar audit but that will come very soon. As for spy tactics and decryption I suggest you see the FAQ for a fairly detailed breakdown of potential attacks an the designed mitigations. A working SAFE network will be very powerful and resistant to almost all known attacks. The devs strive for simple effective code that eliminates unnecessary complexities and will over time with intervention adapt to new attacks.
That said, there are no guarantees. Just strong math and the hope that it is implemented properly. Hope that helps. If not, I leave it to those more thoroughly invested. I’m just a hopeful onlooker with a few things to say. Being here is one the MANY tasks I juggle daily. The main attraction being how passionate this community is. Rare in its makeup. Passion being only a tip of it’s awesomeness. It’s been slow lately, but it’ll soon pick up!