What this does
The file is encrypted with a key derived from your passphrase, using the age format: a public, reviewed design, not something invented for this site. Large files are processed in pieces, so they work on a phone.
The encrypted file gets a neutral name by default, because a name like “redundancy-list.xlsx.age” says a lot without being opened.
What it can’t do
Protect a file after it has been decrypted, or protect one from someone who has the passphrase.
A worked example
An accountant needs a client’s ID scan. The client encrypts it here, emails the .age file, and reads the passphrase over the phone. The email provider and anyone who later gains access to either mailbox sees only an unreadable file.
Questions
- What happens if I forget the passphrase?
- The file cannot be opened by anyone. There is no reset and no back door.
- How does the other person open it?
- On this page, by choosing Decrypt at the top of the tool, adding the .age file and typing the passphrase. Or with the free, open-source age command-line tool, without this website.
- How should I send the passphrase?
- By a different route from the file. If the file goes by email, give the passphrase by phone or in a messaging app.
- What makes a good passphrase?
- Length. Three or more unrelated words are easier to say and type than a short string of symbols, and much harder to guess.
Your file stays on this device
The tool above runs in a sealed frame that cannot send your file anywhere. It works with airplane mode on, and the counter above it stays at 0. Here is how you can check that yourself.
Related tools
- Decrypt a file Open an .age file with its passphrase.
- Make an encrypted ZIP Bundle files into one password-protected ZIP.
- Password-protect PDF Add a password to a PDF, or remove one you know.
- Check a file hash Compare a checksum and see if a file is the type it claims to be.
- Remove metadata Strip location, device and hidden previews from photos and documents.
- Redact PDF Black out names, emails and numbers so they are gone for good.
- Redact image Cover parts of a screenshot or photo with solid boxes.
- Find hidden content Check a PDF or Office file for hidden text, sheets, comments and tracked changes.