Encrypt / Decrypt Text with a Password

This tool locks a message with a password so you can paste it into an email, a note or a chat without others reading it. It uses the browser’s Web Crypto API: the password is stretched with PBKDF2-SHA256 (600,000 rounds) into a 256-bit key, and the text is encrypted with AES-256-GCM, which also detects any change. The result is a single Base64 string that only the same password can open. Nothing is uploaded.

How to use this tool

1. Choose Encrypt, type or paste your text and enter a strong password.
2. Press the button and copy the whole Base64 result.
3. Send the result and share the password through a different channel.
4. To read it, choose Decrypt, paste the Base64 and enter the same password.

Formula

key = PBKDF2-HMAC-SHA256(password, salt, 600,000, 32 bytes); output = Base64(0x01 ‖ salt[16] ‖ IV[12] ‖ AES-256-GCM(key, IV, text) ‖ tag[16])

The salt and IV are random for every message, so identical texts encrypt differently. The 16-byte GCM tag makes decryption fail loudly if the password is wrong or a single character of the output was changed.

Example

Encrypting the 38-byte sentence "Meet me at the north entrance at 7 pm." gives 1 + 16 + 12 + 38 + 16 = 83 bytes, which Base64 writes as 112 characters. Decrypting with "correct horse battery staple" returns the sentence; a password differing by one letter gives "Decryption failed".

Opening the output elsewhere

The format is plain and documented, so any AES-GCM library can read it. In Python with the cryptography package: decode the Base64, take salt = data[1:17], iv = data[17:29], derive the key with PBKDF2HMAC(SHA256(), 32, salt, 600000) and call AESGCM(key).decrypt(iv, data[29:], None).