Last will in ETH?

Hey, I've been wondering whether ETH can provide the function of a last will in sort of a smart contract or similar… I also crossposted this over at /r/cryptocurrency but moons take most of the attention, I guess. 🙂

Anyway.

In case of my death I have to leave some important passwords to others and like to have them stored safely under my control until then.

I'd like to give the other parties access to an encrypted file which contains the passwords / important documents. The password to the encrypted file would only be released from the smart contract if my interaction with it does not happen for a set amount of time. 30, 60, days – any amount of reasonable time.

As long as I am alive I'd also have to sign the smart contract to continuously deny access to the content.

In short: a "if not signed / dead man switch" rule must be obtained to grant access.

How do I achieve this and which project does provide such a functionality? ETH maybe?

Do you think ETH is stable enough to exist in the unforseen future and is reliable enough today in terms of security?

I'd love to hear your ideas. Sorry, I am not a native speaker. 🙂 Thank you!