Expose the JNI scrypt function in a standalone Java class so we can
use it in RecoverableKeyStore as well

Bug: 77325751
Test: It builds. No caller code yet.

Change-Id: I6ff847cff2efbd023612e51fe35be980f27f162d
diff --git a/core/java/android/security/Scrypt.java b/core/java/android/security/Scrypt.java
new file mode 100644
index 0000000..edf8d31
--- /dev/null
+++ b/core/java/android/security/Scrypt.java
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.security;
+
+/**
+ * A Java wrapper for the JNI function to perform the password hashing algorithm SCRYPT.
+ *
+ * @hide
+ */
+public class Scrypt {
+
+    native byte[] nativeScrypt(byte[] password, byte[] salt, int n, int r, int p, int outLen);
+
+    /** Computes the password hashing algorithm SCRYPT. */
+    public byte[] scrypt(byte[] password, byte[] salt, int n, int r, int p, int outLen) {
+        return nativeScrypt(password, salt, n, r, p, outLen);
+    }
+}