Text Encryption and Decryption

This tool encrypts text with AES-256-GCM using a password you choose, and turns it back into readable text when you enter the same password. It all happens in your browser with the Web Crypto API. The protection is only as strong as your password.

Three things happen when you click Encrypt. First, PBKDF2 stretches your password into a 256-bit key using 600,000 rounds of SHA-256 and a random 16-byte salt. This slow step makes each password guess costly for an attacker. Second, AES in GCM mode encrypts the text with a random 12-byte IV, a one-time starting value, so the same message gives different output every time. Third, GCM adds a 16-byte tag that detects tampering. If anyone changes a single character, decryption fails instead of returning garbage.

The result is one Base64 string that holds the salt, the IV, the encrypted text and the tag. It is always 44 bytes longer than your text, and Base64 then makes it about a third longer again. So an 11-character note becomes 76 characters. This layout is specific to this tool, so decrypt it here or with code that reads the same format.

Use it to send a short secret, such as a Wi-Fi password or a private note, through a channel you do not fully trust. Send the password another way, for example by phone. Pick a long random password, for instance from the Password Generator. A short or common password can be guessed, however strong AES is. If you want each person to have their own key pair instead of a shared password, look at the RSA Key Pair Generator.