Encrypting the same file twice produces different results

Each encryption generates a fresh random salt and initialisation vector. Encrypt document.pdf with the same password twice and the two outputs differ completely — different bytes, different hash. This is not a bug. It is the property that makes the encryption sound.

This defeats precomputed-hash attacks

A rainbow-table attack relies on deriving keys for common passwords once, then matching them against many captured files. A random 16-byte salt per file means an attacker must redo the key derivation for every file and every password guess — the precomputation buys them nothing. Combined with PBKDF2-SHA256 at 200,000 iterations, each guess costs real time even on fast hardware.

What happens when you encrypt a file here

The tool applies AES-256-GCM. It generates a 16-byte random salt and a 12-byte random IV, derives the key from your password with PBKDF2 at 200,000 iterations, encrypts the file, and writes a .enc container: the magic bytes 7BB1, then the salt, the IV, the ciphertext, and a 16-byte authentication tag. All of it happens in your browser — the file and the password never leave your device.

Losing the password means losing the file

There is no reset, no backdoor and no recovery service. Forget the password and the file is gone: there is no master key, and brute-forcing a PBKDF2-derived AES-256 key is not practical. The container format is also specific to this site, so only the matching File Decrypter can open it — no third-party utility will. Store the password in a password manager before you close the tab. For sharing a bundle of files instead, see Password-Protect a ZIP.