U+1F510 · emoji since 2010
The padlock with a key means secured and protected, with the key right there. It marks privacy, passwords, and keeping things safe.
It is the icon for encryption and security, the reassurance that your stuff is locked and the key is yours.
In texting, 🔐 does not carry a widely used hidden or slang meaning, so you can usually take it at face value. People send it just as it looks, to add a little visual touch or set the mood of a message. Only a handful of emoji have a separate texting code, and 🔐 is not really one of them.
Its official Unicode name is the Locked with Key emoji. In everyday chat most people just call it the locked with key emoji or describe what it shows. Copy and paste it from the button at the top of this page.
The 🔐 leads off a short phrase, and the rest of the words are written in cipher, every letter disguised as another emoji. Tap decipher to reveal the whole line.
Or make your own cipher in the translator.