Text Encrypt/Decrypt
Encrypt or decrypt text with a passphrase using AES-256-GCM, so only someone with the passphrase can read it.
Why use this tool?
Encrypt a message with a passphrase using AES-256-GCM so only someone with the passphrase can read it, or decrypt a message you received. Everything happens in your browser, and a wrong passphrase is rejected rather than producing garbage.
How to use it
- Choose Encrypt or Decrypt.
- Enter the text and the passphrase (share the passphrase separately from the message).
- Copy the encrypted text, or read the decrypted message.
What happens when you encrypt
Your passphrase is turned into a 256-bit key using PBKDF2 with SHA-256 and 150,000 rounds. The rounds are deliberately slow, so anyone trying to guess the passphrase has to repeat that work for every guess. The text is then encrypted with AES-256-GCM, a widely used standard that both hides the message and detects whether it has been changed.
Each time you encrypt, a new random salt and a new random starting value are created and stored with the result. That's why encrypting the same text with the same passphrase twice gives two completely different outputs, and both decrypt correctly. The result is a block of letters and numbers (base64) that's safe to paste into an email or chat.
Everything happens in your browser. The text and the passphrase are never sent to a server.
Decrypting
Paste the encrypted text, enter the passphrase and choose Decrypt. Because AES-GCM checks the message's integrity, a wrong passphrase or a message that was altered or cut off is rejected with an error rather than turning into garbled text. If decryption fails, check that you copied the whole encrypted block and that the passphrase matches exactly, including capital letters and spaces.
Using it safely
The encryption is only as strong as the passphrase. A short or common word can be guessed; a passphrase of several random words, such as four or five unrelated words, is far stronger and still easy to type.
Share the passphrase through a different channel from the message. If you email the encrypted text, give the passphrase by phone or in person; sending both in the same email gives the protection away.
There is no recovery. If the passphrase is lost, the message can't be decrypted by anyone, including us.
Frequently asked questions
Why is the output different every time?
A new random salt and starting value are used for each encryption. That's intentional: it stops anyone telling whether two messages are the same.
What if I forget the passphrase?
The text can't be recovered. Nothing is stored on a server, so there's no reset option.
Is this the same as end-to-end encrypted messaging?
It uses the same kind of strong encryption, but you manage the passphrase yourself. It's useful for protecting a piece of text you need to send or store, not as a replacement for a secure messaging app.