Johannes Trithemius and Steganography

When looking at stenography, you may as well start at the beginning (or at least as far back as we can get anyway) So we have here, Johannes Trithemius, who was the 24 year old abbot who gave us our earliest modern use of it, back in 1504.
Heres Trithemius' book on the subject, Brian Cole's book on Trimethius and a couple of academic papers.