datapass-verify

# mydatapass-verify

**Independently verify a MyDataPass export — without trusting us.**

[MyDataPass](https://mydatapass.app) delivers customer data offboarding exports as encrypted, audit-logged packages. This repository contains everything a recipient (or their security team) needs to **decrypt and verify an export with zero MyDataPass involvement**: the package format specification and two standalone verifiers.

## Why this repo exists

Our security model does not rely on secrecy of the format — it relies on the strength of the passphrase and standard, auditable cryptography. Publishing the format and the verification tooling means:

- Your security team can review exactly how packages are encrypted **before** signing anything.
- Recipients can decrypt and verify integrity **offline**, with no DataPass servers involved.
- If DataPass disappeared tomorrow, every delivered package would remain fully recoverable with the passphrase and this tooling.

## What's in an export package

A MyDataPass package is a JSON file with four fields:

| Field | Description |
|---|---|
| `ciphertext_b64` | AES-256-GCM ciphertext, Base64 |
| `iv_b64` | 12-byte random nonce, Base64 |
| `salt_b64` | 16-byte random KDF salt, Base64 |
| `hash_sha256` | SHA-256 hex digest of the original plaintext |

Encryption: **AES-256-GCM**. Key derivation: **PBKDF2-HMAC-SHA256, 310,000 iterations, 32-byte key**. Full details in [`docs/export-format.md`](docs/export-format.md).

## Verify an export

### Option A — browser, fully offline

Open [`verify.html`](verify.html) in any modern browser (works from `file://`, no network requests are made). Select the package file, enter the passphrase, and the page decrypts via WebCrypto and checks the SHA-256 digest locally.

### Option B — command line

Requires Python 3.9+ and the [`cryptography`](https://pypi.org/project/cryptography/) package:

```bash
pip install cryptography
python verify.py package.json --out exported-data.bin
```

The script prompts for the passphrase, decrypts, and confirms the plaintext digest matches `hash_sha256`. Exit code `0` means the package is authentic and intact; any tampering with the ciphertext fails GCM authentication.

## What this repo is NOT

This is **not** the MyDataPass product source code. It is the public, auditable surface: the delivery format, the verification tooling, and our [security model](SECURITY.md). Questions or responsible disclosure: **silvia@mydatapass.pro**.

## License

MIT — see [LICENSE](LICENSE).