Encrypt and decrypt text
Turn a message into unreadable text that only someone with the passphrase can open. Encryption happens on your device.
Sealed on this device
Runs in your browser. Nothing is uploaded.
Sealed
Share it with the recipient by another channel than the message, for example in person or by phone.
This passphrase is short. Anyone who gets the encrypted text could try to guess it: use at least 4 random words or 12 random characters.
The two passphrases don’t match.
Encrypted text Decrypted message
The encrypted text will appear here. It is safe to send by email or chat: without the passphrase, it reveals nothing but its approximate length. The original message will appear here.
How it’s protected
AES-256-GCM encryption. The key is derived from your passphrase with PBKDF2-SHA-256 and 600,000 iterations, with a random salt and nonce for every message. Any change to the encrypted text is detected.
How it works
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Write your message
Type or paste the text to protect, then choose a strong passphrase and type it twice.
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Send the encrypted text
Copy the result into an email, a chat or a note. Share the passphrase separately, never in the same message.
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Decrypt on arrival
The recipient opens this page, chooses Decrypt, pastes the text and enters the passphrase.
Frequently asked questions
How secure is this encryption?
It uses AES-256 in GCM mode, a standard used by banks and governments, through your browser’s built-in Web Crypto engine. The key comes from your passphrase via PBKDF2-SHA-256 with 600,000 iterations, which makes each guess slow for an attacker. In practice, the strength depends on your passphrase.
Is my message or passphrase sent to a server?
No. Encryption and decryption run entirely in your browser. Neither the message nor the passphrase is transmitted or stored by this page.
What if I forget the passphrase?
The message cannot be recovered. There is no back door and no reset: that is what makes the encryption trustworthy. Keep the passphrase in a password manager if you need it later.
Why does the same message give a different result each time?
Each encryption uses a new random salt and nonce. This hides whether two encrypted texts contain the same message, and both still decrypt with the same passphrase.
Can I decrypt the text with another program?
Yes, with some code. The text is Base64: one version byte (1), the iteration count as a 4-byte big-endian number, a 16-byte salt, a 12-byte nonce, then the AES-256-GCM ciphertext and its 16-byte tag. The first 33 bytes are authenticated as associated data, and the passphrase is normalized to Unicode NFC before PBKDF2-SHA-256.
Is it suitable for very sensitive information?
It protects the content of a message well, provided the passphrase is strong and shared safely. It doesn’t hide who sent the message or when. For ongoing private conversations, an end-to-end encrypted messenger is more convenient.