# Haskell bindings for Windows DPAPI

This project is to provide Haskell access to Windows's [Data Protection API](https://en.wikipedia.org/wiki/Data_Protection_API).

## Usage

If you have some data that needs protecting such that only your user account
can access it, say the location of your buried treasure,
you could protect it with the following, then save it to a file or somewhere else.

```hs
saveEncrypted :: ByteString -> FilePath -> IO ()
saveEncrypted data filepath = cryptProtectData data Nothing CurrentUser *> writeFile filePath
```

Then you can get back easily, returning Nothing instead of catching an exception
if you can't decrypt it.

```hs
readEncrypted :: FilePath -> IO (Maybe ByteString)
readEncrypted filepath = do
	data <- readFile filepath
	cryptUnprotectDataCheck data Nothing CurrentUser
```

You may want to covert the ciphertext to base64 or some other similar encoding
before saving it, such as when you are saving it to a text file.

## Tests

The tests rely on using PowerShell to protect and unprotect the data, to provide a half that works.
However, this may trip your antimalware service when you run `cabal test`.