Hello Help Desk? I forgot the password to my bullets.

First it was smart guns with secret rings and bracelets. Then came the fingerprint and palmprint technologies. Get ready for password lists and keypads on your firearms next.

An article Password-protected bullets in New Scientist describes a recent patent to do just that.
From the article:

"The way to make firearms really safe, says Hebert Meyerle of Germany, is to password-protect the ammunition itself." . . .
"When they are sold, cartridges could be programmed with a password that matches the purchaser's gun. An owner could set the gun to request the password when it is reloaded, or to perform a biometric check before firing. The gun could also automatically lock itself after a pre-set period of time has passed since the password was entered."

"The system would undoubtedly cost more than a conventional gun, but many firearm enthusiasts would surely pay a premium for such added security."

I guess I can not be considered a "Firearm Enthusiast" because there is no way I would consider this technology until it has seen widespread use by the police and military. If they are not willing to bet their lives on 'Smart Cartridges', I will never bet my family's safety on it either.