Oh, and, the cryptographic choices made in the ST paper are, in retrospect, quite poor: for instance, I had no idea when I picked it that AES-GCM was so troublesome in software, and all of the elliptic curve stuff has since been obsoleted by Elligator.
Anyone interested in hacking on steganographic transports nowadays would be well-advised to begin from something else, such as Yawning Angel's LODP.