File Encryptor

How Do You Encrypt a File with a Password?

Choose a document, photo, archive, or other file in Encrypt mode. Enter a passphrase twice, or use Suggest a passphrase to generate six random words locally. The button becomes available when both fields match and the passphrase contains at least twelve characters or reaches a strength score of three out of four. This rule is a minimum acceptance check, not a promise that every accepted phrase resists guessing equally well.

Select Encrypt file and let the browser finish its work. The output is checked automatically: the tool decrypts the encrypted file and compares the recovered content with the source. Download appears only after this verification passes. Your source file remains on your device. The encrypted download appends .age to its name, so a file called notes.txt becomes notes.txt.age. Save the download before closing the tab.

What Encryption Format Does the Tool Use?

File Encryptor uses the open age format in passphrase mode. It combines scrypt key derivation with ChaCha20-Poly1305 authenticated encryption. Scrypt makes each password guess require substantial computation and memory, while authenticated encryption detects invalid changes to the protected data. A modified or truncated file fails to open instead of being offered as a successfully decrypted file containing wrong bytes. These mechanisms still depend on keeping the passphrase secret and choosing it well.

The format is portable. Recipients can decrypt files here, or install the free open-source age command-line tool on Windows, macOS, or Linux. A basic command is age -d notes.txt.age; age asks for the passphrase interactively. The completion card provides a quoted command for the actual download name. Avoid writing the passphrase into a command, where shell history could retain it. Public-key recipient files require a private key and cannot be unlocked by this page's passphrase field.

Why Does a Strong Passphrase Matter?

Someone who obtains an encrypted file can attempt guesses without asking this page for permission. Scrypt increases the cost of guesses, but cannot turn a predictable phrase into a random secret. Names, birthdays, song lines, repeated characters, and familiar sentences are poor choices even if they are long. Prefer independently selected random words or a long random password that you store safely. The strength estimate is useful guidance, rather than a guarantee about a particular attacker.

A six-word phrase could look like cobalt-lantern-orbit-meadow-velvet-anchor. This published example must never be used as your own secret. Select Suggest a passphrase to make a fresh one with the browser's cryptographic random source, then record it securely. The Password Generator offers other local password options, and the Password Strength Checker explains common guessing patterns. Share the passphrase through a separate trusted channel from the encrypted attachment.

How Do You Decrypt and Recover the Filename?

Drop an age file onto the page. Its binary or text-armored age header selects Decrypt automatically and shows a note. Enter the passphrase and select Decrypt file. Wrong passphrases, damaged files, unsupported work factors, and public-key files produce controlled explanations. No download is offered after a failed operation. A successful decryption restores the file's bytes, with the download name derived by removing the final .age suffix.

The age format does not preserve an original filename inside the encrypted content. Keep the original name before the .age suffix if you want that name restored automatically. If someone renamed the encrypted attachment, rename the decrypted download as needed. The File Hash Verifier can compare a recovered file against a separately supplied checksum when you have one. A matching checksum establishes content equality with that reference, rather than the sender's identity.

What Are the Browser and Privacy Limits?

All file processing and passphrase handling take place locally. The tool does not put passphrases into addresses, persistent browser storage, logs, or error messages. Passphrase inputs are discarded when the completed form is left, when modes change, and when the component is removed. Once the page and its required assets have loaded, it works offline; allow those assets to load before disconnecting. Reloading while offline depends on what your browser has cached.

Very large files depend on device memory. Key derivation itself uses significant memory, and encryption plus automatic verification does more work than simply copying an attachment. A lower-memory phone can fail where a desktop succeeds. There is no universal maximum file size that works on every device. Text armor is available only for source files up to 1 MiB and expands the output. Use Cancel to abandon an operation and try a smaller file if your device struggles.

There is no recovery mechanism. Write the passphrase down securely and keep it accessible for as long as you need the encrypted file. Encryption protects file contents, but the visible download name and approximate size can still reveal context. Choose an appropriate filename before sharing, and remember that other applications may retain copies of the original document or a downloaded plaintext file.