Secretive society of Hider aioids. They are traditionally considered among S<1 sophonts to be masters of encryption and usually disguise themselves as random bits in the datastream or pixels in graphics or virch files. They also are able to intercept and decrypt most communication over the planetary nets and even the Known Net itself. As a result they are great keepers of secrets.
Critics and hackers observe the decryption claims are overblown. Which doesn't mean that people do not believe in them - Plain Sight perfectly fits the urban legend attractor, and has become the perfect fodder of myths, virches and urban myths. Need to add a shady contact to your story in order to advance the plot? Make it a Plain Sight aioid cracking the archailect code. Need some reason things are going badly? It must be the machinations of the Plain Sight. Who knows the location of the Holy Grail? Guess who?
Meanwhile, the real Plain Sight quietly flows through the datastream doing whatever they do in peace.