Added P-384 Utils

[overheadhunter]

Added some utility classes to generate P-384 key pairs, store them to PKCS12 files and load them again.

[overheadhunter]

@SailReal Can you verify if these changes work on Android 7?

Path somePath = ...
P384KeyPair orig = P384KeyPair.generate();
orig.store(somePath, "somePassword".toCharArray());
P384KeyPair loaded = P384KeyPair.load(somePath, "somePassword".toCharArray());
assert orig.equals(loaded);

[SailReal]

Looks very promising but all of java.nio.file was added in API level 26 (Android 8.0) that means it is not possible to get e.g. a Path instance in pre Android 8.0 and pass it to P384KeyPair. Maybe we can provide further methods where we can pass in the input/output-stream of the key material like in MasterkeyFileAccess?

[overheadhunter]

it is not possible to get e.g. a Path instance in pre Android 8.0 and pass it to P384KeyPair.

But it is still possible to load a class that has a Path in some unused method?

So overloading the method such as here works?

cryptolib/src/main/java/org/cryptomator/cryptolib/common/MasterkeyFileAccess.java

Lines 117 to 134 in 3347bc0

	public Masterkey load(Path filePath, CharSequence passphrase) throws MasterkeyLoadingFailedException {
	try (InputStream in = Files.newInputStream(filePath, StandardOpenOption.READ)) {
	return load(in, passphrase);
	} catch (IOException e) {
	throw new MasterkeyLoadingFailedException("I/O error", e);
	}
	}
	public Masterkey load(InputStream in, CharSequence passphrase) throws IOException {
	try (Reader reader = new InputStreamReader(in, UTF_8)) {
	MasterkeyFile parsedFile = MasterkeyFile.read(reader);
	if (!parsedFile.isValid()) {
	throw new IOException("Invalid key file");
	} else {
	return unlock(parsedFile, passphrase);
	}
	}
	}

[SailReal]

But it is still possible to load a class that has a Path in some unused method?

So overloading the method such as here works?

Yes to both questions :)

[sonarqubecloud]

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[SailReal]

LGTM, tested on Android 7 and 11:

val out = applicationContext.openFileOutput("foo", Context.MODE_PRIVATE)

val orig = P384KeyPair.generate();
orig.store(out, "somePassword".toCharArray())

val in = applicationContext.openFileInput("foo")

val loaded = P384KeyPair.load(in, "somePassword".toCharArray())

=> orig.equals(loaded) == true