Add scrypt-based password stretching.

Bug: 27056334
Change-Id: Ifa7f776c21c439f89dad7836175fbd045e1c603e
diff --git a/ScryptParameters.h b/ScryptParameters.h
new file mode 100644
index 0000000..1b43ea5
--- /dev/null
+++ b/ScryptParameters.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2016 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.
+ */
+
+#ifndef ANDROID_VOLD_SCRYPT_PARAMETERS_H
+#define ANDROID_VOLD_SCRYPT_PARAMETERS_H
+
+#include <stdbool.h>
+#include <sys/cdefs.h>
+
+#define SCRYPT_PROP "ro.crypto.scrypt_params"
+#define SCRYPT_DEFAULTS "15:3:1"
+
+__BEGIN_DECLS
+
+bool parse_scrypt_parameters(const char* paramstr, int *Nf, int *rf, int *pf);
+
+__END_DECLS
+
+#endif