Encrypt a File
Lock any file with a password before you send it, using AES-256 in your own browser.
What it does
Encrypt a File uses the cryptography built into your browser (WebCrypto) — the same standard algorithms your bank's site uses — on a file or a piece of text that never leaves this page.
When you need it
Before sending something sensitive by email or chat, when a file you received must be checked, or when you want to know whether a password or a signature holds up.
Limits and caveats
A strong algorithm is only as safe as the password or certificate behind it, and some checks — whether a certificate was revoked, say — need the issuer's servers, which the page says where it matters. Nothing is stored or logged. Everything happens in your browser, so the file never leaves your device.
How to encrypt a file
- Drop the file.
- Choose a password — and tell the recipient some other way than the file.
- Send the .kivo file. Only that password opens it.
Everything happens on this device: no file is uploaded and nothing leaves the browser.
Frequently asked questions
- Isn't a zip password enough?
- No. The legacy ZIP cipher is broken well enough that a laptop gets through it in minutes, and most tools still use it by default. This is AES-256-GCM with a key stretched by 310,000 rounds of PBKDF2, which is the current recommendation rather than a 1990s one.
- Can you recover my file if I forget the password?
- No, and nobody can — that is what makes it worth using. There is no copy of the key, no reset, and no back door. Write the password down somewhere safe before you send anything.
- Who else can open a .kivo file?
- Only this tool, and that is the honest limitation. Standard containers like OpenPGP would open anywhere, but shipping an implementation of one is a much bigger promise to keep correctly. For sending something to somebody you can point at this page, that trade is fine; for a long-term archive, use a tool with a standard format.
- Is the filename hidden?
- No. The name is stored in the clear so the recipient knows what they received; only the contents are encrypted. Rename the file first if the name itself is sensitive.
- Do my files get uploaded?
- No. This tool runs entirely in your browser, so the file never leaves your device.