Protected document builder
Pick a file and a password; this page produces a single self-contained HTML file that decrypts and downloads it. Everything runs in your browser - nothing you enter is ever uploaded.
File (or secret message)
The document(s) to encrypt: pick one or more files, or protect a written message. You can also drop files onto this card.
Tip: drag and drop files here to select them. Selecting several files produces one bundled output with a file list on its unlock page.
Used only in your browser to derive the encryption key. Never stored, never transmitted. There is no way to recover it, so keep a copy somewhere safe. This password is recipient 1; add more recipients below.
Must match the password above exactly. A typo here is the most common way a protected file becomes impossible to open.
Every visible element can be toggled on or off for this build, and colors/text default to the project theme.
When generated, every file shows a "Share this file" button and a QR code of the page URL (when served over http(s)). Turn this off to omit the button, QR, and the embedded QR encoder entirely from the built file.
Legal, privacy, and learn-more buttons. These are fixed to this deployment and cannot be changed here; every generated file always includes all three, and each opens in a new tab when a visitor clicks it.
Sign the ciphertext with an ECDSA P-256 key so a recipient can verify the file came from you and was not altered. The signature proves the file was not tampered with since signing; it does NOT prove who sent it, because the public key ships inside the same file. A recipient only sees a green "verified" badge after they confirm this file's key fingerprint with you out-of-band. Share that fingerprint separately (e.g. chat, card, phone call) - never through the file itself.
Shown to recipients as the stated sender. This label is not authenticated by itself - recipients verify your key fingerprint out-of-band, then the label is just a convenience.
Keep the private key. Recipients only learn its public half (embedded in each signed file) and the 8-byte fingerprint of it, which is what they confirm out-of-band. Reuse the same key across builds so recipients can recognize you by a stable fingerprint.
Encrypt one file to several recipients at once. The ciphertext is wrapped once per recipient, so the built file opens for any of them. You can mix passwords and public keys. This is what lets you send a file to someone's key instead of a password over chat.
The file's password can be cracked offline, so the default Argon2id is the strongest protection. Choose the PBKDF2 mode only when a FIPS-listed KDF is required; it is still 600,000-iteration HMAC-SHA256 with the same key-commitment.
Create a public/private pair to hand to someone else. Share the public key, and they encrypt to it; the recipient keeps the private key and pastes it into the built file to unlock.
Reuse public keys you have already generated or imported without copying them by hand. Public keys are public material. Nothing is written to your device unless you click Save or Import.
Optional extra stylesheet, inlined into the output after the built-in theme so it can override it. External requests are stripped so the file stays self-contained and works offline.
Working... 0s elapsed. Large file? Compression and Argon2id take a moment.