Encrypt and Decrypt Files with a Password

How it works

Choose your file by tapping or clicking the box, type a password and press Apply. Encrypting payslip.pdf, for example, downloads a new file named payslip.pdf.enc — you can e-mail it or put it in cloud storage without worry, because the content cannot be opened without the password. The recipient (or future you) opens this same page, switches the direction to "Decrypt" and types the same password to get the original file back byte for byte; the file name is stored encrypted inside, so the decrypted file comes back under its own name. Everything runs inside your browser on your device — neither the file nor the password is ever sent to any server. Note that the password field is shown in plain text, so be careful if someone can see your screen. If you need to hand the password to someone, use a different channel from the one carrying the file — say it over the phone rather than putting it in the same e-mail.

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What is AES-256?

AES is the symmetric encryption standard published by the US standards institute NIST in 2001; the 256 is the key length in bits. Symmetric means the same key both locks and unlocks the data — on this page that key is derived from your password. A 256-bit key has 2 to the power of 256 possible values, a space no known computing power can search. This tool uses AES in GCM mode, which does more than hide the content: it appends an authentication tag to the output, so if even a single byte of the file changes in transit, decryption fails with a clear error instead of silently producing corrupted data.

What is PBKDF2 (deriving a key from a password)?

Passwords people type are far too short and guessable to serve as encryption keys directly. PBKDF2 turns a password into a fixed-length key by combining it with a random salt and feeding it through a hash function hundreds of thousands of times. This tool uses 600,000 rounds: the half second that costs your device once is the same slowdown an attacker pays for every single password guess, which makes brute-forcing dramatically more expensive. Because a fresh salt is generated for every file, two files encrypted with the same password produce completely different output.

What is the difference between encryption and hashing?

Both are cryptographic operations, but they point in opposite directions. Encryption is two-way: anyone with the right password recovers the original content exactly — its purpose is keeping content away from unauthorized eyes. A hash is one-way: it produces a fixed-length fingerprint of a file from which the file can never be reconstructed — its purpose is proving content has not changed. To deliver a file to someone privately, encrypt it; to let anyone verify that a publicly posted file arrived intact, publish its hash. This site has a separate page for each job.

Lose the password and the file is gone

This tool has no back door, no recovery question and no "forgot password" link — deliberately, because any recovery path we could use would be a weakness an attacker could use too. There is no known practical way to open an AES-256-encrypted file without its password; if the password is lost, the content is mathematically gone. When encrypting anything important, store the password in a password manager or write it down somewhere physically safe.

The second trap is password strength: however solid the encryption, the door opens if an attacker can guess the password. PBKDF2's 600,000 rounds slow every guess down, but they cannot save a short, predictable password like a birth date or a single dictionary word. Use a random password of at least 12-16 characters — the password generator on this site exists for exactly this.

How to use it in practice

The output is a single .enc file in this tool's own format: a signature identifying the file, the key-derivation salt and the encrypted body. Decryption happens on this same page — send the recipient this page's address and the password through separate channels and that is all they need. You may freely rename the .enc file: the original name is stored encrypted inside and comes back on decryption. If the file name itself gives something away (say, resignation-letter.docx), rename the .enc file to something meaningless before sending it.

• Before e-mailing or cloud backup → encrypt the file, pass the password through a separate channel
• Documents carried on a USB stick → if it is lost, the content cannot be opened without the password
• Long-term archives → store the password in a password manager; an archive without its password is a lost archive
• Several files at once → select them all; each file is encrypted separately with its own salt

Frequently asked questions

Can you recover my file if I forget the password?

No. Encryption runs on your device, your password never reaches us, and the format has no back door. There is no known practical way to open an AES-256-encrypted file without its password — a lost password means lost content. Keep the password in a password manager.

Is my file or password sent to a server?

No. Encryption and decryption run entirely inside your browser using its built-in crypto engine (crypto.subtle). Neither the file, nor its name, nor the password ever crosses the network — and this site's security headers block the page from sending data anywhere in the first place.

Can I open the .enc file with WinRAR or 7-Zip?

No — .enc is this tool's own format, not an archive format. To decrypt, open this page, switch the direction to "Decrypt" and type the same password. Send the recipient this page's address; no account or installation is needed.

Will the file still decrypt if I rename the .enc file?

Yes. The original file name is stored encrypted inside the .enc file; even if you delete or completely change the visible name, decrypting with the right password brings the file back under its original name. If the name itself is sensitive, rename the .enc file to something meaningless before sending it.