Which Italian Renaissance polymath invented a method to writing secret messages on the inside of eggs for communication with his friends who had been imprisoned by the Spanish Inquisition?

Giambattista della Porta (1535-1615) was a polymath and playwright from Naples. As many of his friend were imprisoned, he found a way to communicate with them through secret messages written on the inside of eggs. He used a mixture of plant pigments and alum which penetrated the porous egg shell. Then he boiled the egg in hot water and the ink on the outside of the egg was washed away. When a visitor came to the gate of the prison, everything was checked except for eggs. Della Porta himself wrote in his "Magia Natularis" (1590):

...pontificalium suffragiorium comittiis ova non incipiuntur nec aliquid fraudis in eis suspicatur...

which translates as: "...eggs are not stopped by the Papal Inquisition and no fraud is suspected to be in them..."

When the recipient in prison peeled off the shell, the message was revealed once again on the egg white.


Sources:
https://en.wikipedia.org/wiki/Giambattista_della_Porta
https://www.logbuch-wissensgeschichte.de/2633/egg-and-inquisition/