Signet Ring = Early 2 Factor Authentication
|Photo: A. Reinkober / pixelio.de|
|Difficult to copy||Supposedly impossible to copy|
|Seal proves personal involvement of bearer||2FA token proves personal interaction of owner|
The main difference is of course that 2FA is commonly available to everybody who needs it while signet rings where and remain a special feature. But it is still nice to know that the basic idea is several thousands years old.