Letterlocking (nonfiction)

Letterlocking is the practice of folding and sealing a letter or other document such that the letter cannot be opened and re-closed without revealing that the fact that the letter has been opened.

The term was a term coined by MIT Libraries conservator Jana Dambrogio after she discovered a trove of letters which had been ingeniously folded and sealed so that they couldn't be opened and re-closed without revealing that they had been read. Some even contained "booby traps" to catch the unwary.

Dambroglio and her colleagues have since been painstaking reconstructing these long-lost letterlocking techniques (which they hypothesize led to the development of the modern envelope), and documenting their findings in an online Letterlocking dictionary that documents the techniques, tools, and jargon of their discipline.

https://boingboing.net/2019/03/15/security-thru-topology.html

http://www.janadambrogio.com/

Fiction cross-reference

• Gnomon algorithm
• Gnomon Chronicles
• The Sigil (crime fighter)

Nonfiction cross-reference

External links:

• Seal (emblem) @ Wikipedia