Question 1

Does this cryptographically prevent early decryption?

Accepted Answer

No. A technically capable holder can recover the message from the envelope before the target date. The unlock time is enforced by this tool, not by the encryption itself. Use it for scheduling and honor-system seals, not against a motivated adversary.

Question 2

What is the Drand beacon used for here?

Accepted Answer

As a shared, verifiable public clock: decryption checks that the beacon has published the round matching your target time. It does not currently supply the decryption key, which is why the lock is not cryptographic.

Question 3

What would make it a real time-lock?

Accepted Answer

True time-lock uses identity-based encryption where the decryption key is the Drand signature for the target round — a value that literally does not exist until that round publishes. That (the tlock construction) is a planned enhancement.

Question 4

Does this work in air-gap mode?

Accepted Answer

Encryption yes. Decryption fetches the target Drand round from api.drand.sh, so it needs network access and is disabled in air-gap mode.

Question 5

What should I actually use it for?

Accepted Answer

Non-adversarial scheduling: a note to your future self, a reveal you intend to publish later, a countdown envelope. For secrecy against someone holding the envelope, encrypt to a recipient key instead.

Zeitsperre