An intro to Insertabeles, as published in ACM interactions. 

Imagine Dylan, a bureaucrat working in a foreign embassy. Dylan approaches a security door, arms overflowing with confidential reports. Dylan leans toward the door’s access sensor and is authenticated. The door is now unlocked and can be easily pushed open with one shoulder, without the need to put down the documents and fumble for his keys or an access pass. Dylan has an insertable device implanted subcutaneously in his hand that interacts with the transponder at the office door.

It may read as science fiction, but it's already a reality.