National Security Action Memorandum 160

Evidence that NSA was the first to discover public-key cryptography, a decade before Whit Diffie and Martin Hellman did in 1976. This is a sanitized copy of NSAM 160, titled "Permissive Links for Nuclear Weapons in NATO".

NSAM 160 Text

Recently, I saw a post to a mailing list by Steve Bellovin regarding the origins of public-key cryptography, and some evidence that NSA discovered the technique before Diffie and Hellman.

He has a web page giving more insight. It includes a copy of National Security Action Memorandum (NSAM) 160 that had been sanitized. Unfortunately, the electronic version of the document is graphical, from a scanned FAX copy. For folks (and programs!) unable to read the memo in its graphical form, I've converted the documents to HTML. If you find any errors in my conversion, please let me know so I can make the corrections.

There are a few parts where the text is barely legible, in which case I made my best effort to convert the text faithfully.

Thanks to Steve Bellovin and Matt Blaze for shedding some light on an important piece of the history of cryptography.

Enjoy.