How SafeShare works

All encryption and decryption happens in your browser. The server stores only ciphertext and can't read any secret. Neither can anyone who copies its database, backups or logs.

Share a secret

Use this when you have the secret and a reasonably trusted way to reach the recipient.

Your browser generates a random 256-bit key and encrypts the text with AES-256-GCM. An optional passphrase is stretched with PBKDF2 (600,000 iterations) and mixed in with HKDF.
The key goes after the # in the link. Browsers never send that part to the server.
Send one link, or send the link and the key through two different channels (e.g. e-mail + chat).
Opening the link shows a confirmation page first, so chat link previews can't use up the secret. The server hands over the ciphertext once and deletes it in the same step.

Request a secret

Use this when someone outside your organisation (a client or a vendor) has to send you a secret and you have no channel you both trust.

Your browser creates an ECDH P-256 key pair. The private key is stored in this browser and can't be exported. The server only receives the public key.
You send the request link. It contains nothing secret, so plain e-mail is fine.
Both of you see the same security code (a fingerprint of your public key). Read it to each other over the phone or a video call. If the codes match, nobody has swapped the key on the way.
The sender's browser encrypts the secret to your public key. Only your browser can decrypt it, once. After that, the ciphertext is deleted from the server and the private key from your browser.

Auto-burn timer

Secrets and requests can burn automatically after a time you choose, whether or not they have been opened. The maximum is 43200 minutes.
The timer is optional. Without one, an item lives until it is opened, cancelled or destroyed.
For requests, both sides can set a timer. The shorter one applies.

Limits

Anyone who gets a full share link before the recipient opens it can read the secret. For anything sensitive, send the link and key separately, or use a request.
After 5 wrong key or passphrase attempts, a shared secret is destroyed. Someone with only the link can't read it, but can destroy it this way. The recipient will notice and should tell you.
A request can only be opened in the browser where it was created. Private windows and clearing site data lose the key.
Someone who controls the server could change the JavaScript it serves. This applies to every browser-based encryption tool.