Everything happens locally using your browser's built-in Web Crypto API. No file, password, or text is ever sent anywhere — you could disconnect from the internet and this would still work.
- Cipher: AES-256-GCM — encryption and tamper-detection in one step. If a single byte of the encrypted output changes, decryption fails loudly instead of silently returning corrupted data.
- Key derivation: PBKDF2-HMAC-SHA256, 600,000 iterations (current OWASP minimum) with a fresh random 16-byte salt every time — this is what makes deriving a key from your password take a moment.
- Crack-time estimate: based on character-set entropy and this tool's PBKDF2 cost, assuming one high-end GPU attacking the file offline. It assumes a truly random password — dictionary words and predictable patterns crack far faster than the estimate suggests, no matter how long they are.
- Files are streamed in 4MB chunks, each with its own nonce, so large videos don't have to fit in memory all at once. The total length is checked against an authenticated record of the original size, so silently dropped or reordered chunks are rejected rather than handed back as a truncated file.
- Nonce: every chunk (and every text encryption) gets its own nonce derived from a random per-operation base value, so nothing is ever reused.
- Metadata: the original filename and file type are encrypted and authenticated in their own block, not stored in the open.
There's no password recovery, by design — if you lose the password, the data is unrecoverable. For very high-stakes or long-term secrets, consider a dedicated tool like age or GPG alongside this.