"Cipher Disk" before Alberti

I recently learned that before Leon Battista Alberti's treatise, there had been ideas similar to his cipher disk. In particular, Giovanni Fontana's disk for mnemonics looks very similar to Alberti's cipher disk, though there is no evidence Alberti knew this. (Another interesting thing about Fontana is that his ideas are described in a manuscript booklet almost entirely in cipher.)
I uploaded a short article about this: "Giovanni Fontana's "Cipher Disk" (ca. 1430) in an Encrypted Booklet". (This was delayed several weeks because of troubles of my PC....)