Ask someone to send you a secret.
You get two links: a write-only reply link to send them, and a private pickup link that only you should keep. Their browser locks the secret to a key that never leaves your pickup link.
Open a letterbox
If they reply, you must pick the secret up before the same timer runs out. After you open it, the server copy is deleted.
How does a letterbox work?
- A key stays with youYour browser makes a lock and a key. The lock (a public key) is stored with the empty letterbox. The key rides in your pickup link after the
#. - They write, they cannot readThe reply link has no key. They get one look to check it (stray spaces and invisible characters are pointed out), then their browser encrypts it to your lock and forgets it. Someone who sees only that link cannot decrypt what they type.
- Posted is not openedBoth pages show a simple trail: letterbox opened, secret posted, unlocked. The sender can only check whether it is still waiting. There is no read receipt.
- You pick it up onceYour pickup page waits until something arrives, then burns the server copy when you reveal it.
Is this safer than asking them to email it?
Yes, for the usual case. Email keeps the secret in both inboxes and backups. Here the chat only holds a write-only link, and the secret itself is readable only with your pickup link. Read the plain-words guide.
What if someone else opens the reply link first?
They could put junk in the letterbox, or a fake secret. They still cannot read a real reply afterwards, because they don't have your pickup key. If the pickup page shows a secret you weren't expecting, don't use it, close the letterbox and ask again over a trusted channel.
Will they know when I've read it?
No. They can see that it was posted and whether it is still sitting in the letterbox. When it has gone, it was collected or the letterbox was closed, which isn't proof a person read it. If it matters, tell them you have it.
Can't they just send me a one-time note instead?
They can, and that works too. A letterbox is handy when you want to start the request, give them a page that is ready to type into, and watch for the reply yourself.