Encrypt a note before pasting it into chat or email

The job

You need to send a colleague a recovery code, but the chat history lives forever. Encrypt the text with a password here, paste the base64 block into the chat, and tell them the password by a different channel — a call, in person, anywhere that is not the same thread.

Worked example

Choose Encrypt, paste the recovery code, set a password like a four-word phrase (the password generator can help with random secrets). The output is one base64 block. The recipient opens the same tool, chooses Decrypt, pastes the block, enters the password, and gets the original text back.

• Each encryption uses a fresh random salt and IV, so encrypting the same text twice gives different blocks.
• The key is derived from your password with PBKDF2-SHA-256, 200,000 iterations; the cipher is AES-256-GCM.

What it protects — and what it does not

It protects the message content from anyone who can read the chat but does not have the password. It does not hide that a message was sent, who sent it, or when — chat logs still show that. It is not a password manager: nothing is stored, and a forgotten password means the text is gone for good. If the password is weak, the encryption is weak; use a long one.

Limits

Text up to 200,000 characters. The whole thing runs in your browser with WebCrypto — the text and password never leave the page. Both sides need this tool (or an equivalent AES-GCM/PBKDF2 implementation) to round-trip.