Not all covert communications is electronic. Some is physically transfered.

A dead drop is both the technique of passing a physical message and also the place where a message might be left for later collection.

In the movies a coded message is rolled up, put into something, and then dropped/placed someplace where the next person in the spy message chain would recover te message, taking it away for decoding.

Variations are endless, though usually they tend to be focused on message delivery and security/annonimity for the people passing the message.

This may be relaxed if the message collector is a person protected by diplomatic immunity.

Complex systems may involved several stages of dead drops, though that added complexity has its own risks to the secrecy of both the message and message passing routine.

Sometimes the message might be photos, film, or microdots or perhaps even a USB drive.

--- Steve K9ZW via SPOT BBS

--- Mystic BBS v1.12 A48 2022/02/11 (Linux/64)
* Origin: SPOT BBS / k9zw (700:100/69)