Hacker News
- Permissive Action Links – how nuclear weapons are secured https://www.cs.columbia.edu/~smb/nsam-160/pal.html 8 comments
- Permissive Action Links http://www.cs.columbia.edu/~smb/nsam-160/pal.html 6 comments programming
- Spaceballs in real life: Can you quess the seven digit secred code (Permissive Action Link) used to prevent unauthorized launch of strategic missiles during cold war? http://www.cdi.org/blair/permissive-action-links.cfm 14 comments reddit.com