AES-256 Encryption/Decryption

About this tool

Encrypts or decrypts a piece of text with a passphrase using AES-256 in GCM mode. The tool derives the key from your passphrase with PBKDF2 (SHA-256, 100,000 iterations) and a random 16-byte salt, and uses a random 12-byte IV for every encryption. The result is a single Base64 string containing the salt, the IV and the ciphertext, so the same text encrypts to a different string each time. GCM also authenticates the data, so a wrong passphrase or altered ciphertext fails to decrypt instead of returning garbage. Everything runs in your browser with the Web Crypto API; your text and passphrase are not sent to our server.

How to use it

1. Choose Encrypt or Decrypt.
2. Enter a passphrase. Use a long, unique one, because the key is only as strong as the passphrase.
3. Paste your plain text (to encrypt) or the Base64 string produced earlier (to decrypt).
4. Run the tool and copy the result. Keep the passphrase somewhere safe; it cannot be recovered.

Common problems

Decryption failed (wrong passphrase or corrupt input)

The passphrase must match exactly, including case and spaces. Also make sure you pasted the whole Base64 string with nothing added or cut off.

Output cannot be decrypted by another tool

The format is specific to this tool (salt + IV + ciphertext in one Base64 string). Other software will need the same layout and key derivation settings to read it.

Encrypting the same text gives a different result each time

This is expected. A fresh random salt and IV are used for every run, which is what makes the output safe to store.