What it does
Encrypt / Decrypt protects text with AES, the standard cipher used by banks and governments. Use a password (turned into a key with PBKDF2-SHA256) or a raw key, and choose AES-GCM (recommended), CBC or CTR with a 128 or 256-bit key. Everything runs in your browser with the Web Crypto API.
How to use it
- Choose Encrypt or Decrypt.
- Choose the key source: Password, or Raw key (paste hex or click Generate key).
- Pick the mode, the key size and the output encoding (Base64 or Hex).
- Type or paste the text. The result appears on the right; copy or download it.
To decrypt, use exactly the same password or key, mode, key size, encoding and PBKDF2 rounds.
What the output contains
The output holds everything needed to decrypt except the password or key:
| Part | Size |
|---|---|
| Salt (password mode only) | 16 bytes |
| IV | 12 bytes for GCM, 16 for CBC and CTR |
| Ciphertext | same length as the text (CBC pads to 16-byte blocks) |
| Authentication tag (GCM only) | 16 bytes |
Because the salt and IV are random, encrypting the same text twice gives different results. That is expected.
Good to know
- AES-GCM detects tampering: change one character of the ciphertext and decryption fails. CBC and CTR do not, so use them only for compatibility.
- The default of 600,000 PBKDF2 rounds follows OWASP's advice. More rounds make guessing passwords slower for attackers, and slightly slower for you.
- A strong password matters more than any setting. The Password Generator can make one.
FAQ
Can I decrypt this with OpenSSL or Python? Yes, if you split the output into salt, IV, ciphertext and tag as shown above and derive the key with PBKDF2-SHA256 and the same rounds. Our test suite decrypts the output with Node's crypto module to check exactly that.
What happens if I forget the password? The text cannot be recovered. There is no back door.