Time Capsule: Send a Message to the Future

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How it Works

Using cryptography, we can encrypt a message and throw away the key so that it would take a normal (classical) computer millions of years to recover the original message. If we do the encryption using elliptic-curve cryptography, then a classical computer will still need millions of years to recover the message, but a large-scale quantum computer, if we had one, would be able to recover the message in a matter of weeks. This gives us a unique opportunity to save messages in a format that won't be possible to read until somebody manages to build a quantum computer.

So, use the form above to encrypt and upload a message that will remain unreadable until either someone builds a large-scale quantum computer or, in an unexpected breakthrough, someone discovers a way to recover the messages using a classical computer. It's not known how long it will be before we can build large-scale quantum computers. Some scientists guess that we'll see one within the next 10 years, others guess that it'll take 50 years or more, and some don't think we'll ever be able to build one. So, it's impossible to say when your message will be read, if at all. But it's worth a try!

Message Archive

It might take a long time for humanity to invent the technology we need to read these messages, and this website will probably go down before then. So, after you've added your message, please consider downloading the entire archive so that a future historian might one day find your copy of it.

The archive currently contains 1144 messages. The last message was added 2 days ago.

Future historians would like to know that their version of the archive is authentic. To help prevent fakes, once a year I will embed a cryptographic hash of the archive into a cryptocurrency's blockchain. Historians will be able to check the blockchain's "proof of work" so that anyone trying to rewrite years-past history will need to have enormous computational resources at their disposal.


  1. The SHA256 hash f4233140fde1f1efe75d867eeb17cc34ae91a0165f767d6908ed7e3e3bb33b09 of the first 1338 lines of the archive can be found in transaction ff8221a3ee3322b36ef5817a0a591d7001c0fca2f549b5aa0c2a2b712fe6315a in block 178,991 of the Zcash blockchain.
  2. The SHA256 hash 4c72f9ca9a5ea691ed694f6091263d229752f6424cd6048dfbfda3f2498ffa3a of the first 1825 lines of the archive can be found in transaction 30ae065eb7d6860776abaa0b1fbb02144d8295a4c803ec44118204b61f8cfa29 in block 476,431 of the Zcash blockchain.