# Encrypt File

> Encrypt or decrypt a file with a password in your browser. AES-256-GCM in compact JWE, nothing uploaded. Lose the password and the file cannot be recovered.

- URL: https://bytescope.dev/en/encrypt-file/
- Locale: en · Also: [ja](https://bytescope.dev/ja/encrypt-file.md) · [zh-Hant](https://bytescope.dev/zh-Hant/encrypt-file.md)
- Runs: Your files never leave your browser — all processing is local.
- Requires: Any modern browser (Chrome, Edge, Firefox, Safari), desktop and mobile.
- Updated: 2026-09-08

## What it does

A password stays in this tab. The file is encrypted with AES-256-GCM; the content key is wrapped with PBES2-HS256+A256KW (PBKDF2-HMAC-SHA256, 600,000 iterations). The container is compact JWE from RFC 7516 / 7518 — not a homemade box. Decrypt the `.jwe` on the same page. Nothing is uploaded, and there is no account that could hold a recovery key.

### Why JWE and not a mystery `.enc`

A private container is how files get stranded when the site disappears. Compact JWE is an existing open format with published test vectors (RFC 7516 Appendix A.1 for A256GCM, RFC 7517 Appendix C for PBES2 key wrap, RFC 3394 §4.6 for the 256-bit wrap). Other JWE tools that implement the same `alg` / `enc` pair can read the file; this page does not invent a header.

### If the password is gone, the file is gone

There is no reset mail, no security questions, no 'we can unlock it for you'. That is the point of doing this in the browser: we never see the password, so we cannot give it back. Write it down somewhere that will still exist next year before you delete the plaintext.

## Limits

Does not recover a lost password and does not share or store files; it encrypts and decrypts with a password locally.

If you lose the password, the file cannot be opened. We cannot recover it. There is no reset, no email, no back door.

## FAQ

### Is my file or password uploaded?

No. PBKDF2, AES key wrap and AES-GCM all run in this tab via the Web Cryptography API. There is no endpoint that accepts the file.

### I lost the password — can you unlock the file?

No. If you lose the password, the file cannot be opened. We cannot recover it. That is not a policy choice we could relax later; the key never existed on a server.

### What format is the encrypted file?

Compact JWE (five base64url segments). Header `alg` is `PBES2-HS256+A256KW`, `enc` is `A256GCM`. Keep the `.jwe` extension so you can find it again.

### Can another program decrypt it?

Any implementation of that JWE `alg`/`enc` pair can, in principle. This page is not a lock-in. A tool that only speaks age or zip-AES will not open it — those are different formats.

### How slow is the password stretch?

PBKDF2-HMAC-SHA256 at 600,000 iterations, the OWASP 2023 figure for SHA-256. A short wait on encrypt and decrypt is the cost of not storing a fast-to-brute-force key.

## Related tools

- [File Hash Calculator](https://bytescope.dev/en/file-hash.md) — Hash the file before you encrypt it, if you need a checksum later.