120 · Security Tools

Text Encryption & Decryption

Turn a message into unreadable text that only someone with the passphrase can decrypt. Encryption happens on your device.

Mode

Nobody, including CapyHelp, can recover the text if you forget it.

How to use the text encryption & decryption

  1. Type your message and a strong passphrase.
  2. Choose Encrypt, then select the button.
  3. To read it later, paste the TLR1… text, choose Decrypt and enter the same passphrase.

How it works

Your passphrase is stretched into a 256-bit key with PBKDF2-SHA256 (600,000 rounds and a random salt), which makes guessing passphrases slow. The message is encrypted with AES-256-GCM, which also detects any change to the encrypted text. The result starts with TLR1. followed by the salt, nonce and ciphertext in Base64.

The security depends on your passphrase: use several random words, share it separately from the message, and remember that nobody can recover a forgotten passphrase.

Examples

Encrypt “meet at 6” with a passphrase

TLR1.… (different every time)

Decrypt with the wrong passphrase

Wrong passphrase, or the encrypted text was changed.

Questions

Why is the result different every time?

A new random salt and nonce are used for each encryption. That’s expected and makes the encryption stronger.

Is anything sent to CapyHelp?

No. The message, the passphrase and the result stay in your browser.