1 files changed, 147 insertions, 0 deletions
diff --git a/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/generators/SCrypt.java b/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/generators/SCrypt.java
new file mode 100644
index 000000000..c199adbf2
--- /dev/null
+++ b/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/generators/SCrypt.java
@@ -0,0 +1,147 @@
+package org.spongycastle.crypto.generators;
+
+import org.spongycastle.crypto.PBEParametersGenerator;
+import org.spongycastle.crypto.digests.SHA256Digest;
+import org.spongycastle.crypto.engines.Salsa20Engine;
+import org.spongycastle.crypto.params.KeyParameter;
+import org.spongycastle.crypto.util.Pack;
+import org.spongycastle.util.Arrays;
+
+public class SCrypt
+{
+    // TODO Validate arguments
+    public static byte[] generate(byte[] P, byte[] S, int N, int r, int p, int dkLen)
+    {
+        return MFcrypt(P, S, N, r, p, dkLen);
+    }
+
+    private static byte[] MFcrypt(byte[] P, byte[] S, int N, int r, int p, int dkLen)
+    {
+        int MFLenBytes = r * 128;
+        byte[] bytes = SingleIterationPBKDF2(P, S, p * MFLenBytes);
+
+        int[] B = null;
+
+        try
+        {
+            int BLen = bytes.length >>> 2;
+            B = new int[BLen];
+
+            Pack.littleEndianToInt(bytes, 0, B);
+
+            int MFLenWords = MFLenBytes >>> 2;
+            for (int BOff = 0; BOff < BLen; BOff += MFLenWords)
+            {
+                // TODO These can be done in parallel threads
+                SMix(B, BOff, N, r);
+            }
+
+            Pack.intToLittleEndian(B, bytes, 0);
+
+            return SingleIterationPBKDF2(P, bytes, dkLen);
+        }
+        finally
+        {
+            Clear(bytes);
+            Clear(B);
+        }
+    }
+
+    private static byte[] SingleIterationPBKDF2(byte[] P, byte[] S, int dkLen)
+    {
+        PBEParametersGenerator pGen = new PKCS5S2ParametersGenerator(new SHA256Digest());
+        pGen.init(P, S, 1);
+        KeyParameter key = (KeyParameter) pGen.generateDerivedMacParameters(dkLen * 8);
+        return key.getKey();
+    }
+
+    private static void SMix(int[] B, int BOff, int N, int r)
+    {
+        int BCount = r * 32;
+
+        int[] blockX1 = new int[16];
+        int[] blockX2 = new int[16];
+        int[] blockY = new int[BCount];
+
+        int[] X = new int[BCount];
+        int[][] V = new int[N][];
+
+        try
+        {
+            System.arraycopy(B, BOff, X, 0, BCount);
+
+            for (int i = 0; i < N; ++i)
+            {
+                V[i] = Arrays.clone(X);
+                BlockMix(X, blockX1, blockX2, blockY, r);
+            }
+
+            int mask = N - 1;
+            for (int i = 0; i < N; ++i)
+            {
+                int j = X[BCount - 16] & mask;
+                Xor(X, V[j], 0, X);
+                BlockMix(X, blockX1, blockX2, blockY, r);
+            }
+
+            System.arraycopy(X, 0, B, BOff, BCount);
+        }
+        finally
+        {
+            ClearAll(V);
+            ClearAll(new int[][]{ X, blockX1, blockX2, blockY });
+        }
+    }
+
+    private static void BlockMix(int[] B, int[] X1, int[] X2, int[] Y, int r)
+    {
+        System.arraycopy(B, B.length - 16, X1, 0, 16);
+
+        int BOff = 0, YOff = 0, halfLen = B.length >>> 1;
+
+        for (int i = 2 * r; i > 0; --i)
+        {
+            Xor(X1, B, BOff, X2);
+
+            Salsa20Engine.salsaCore(8, X2, X1);
+            System.arraycopy(X1, 0, Y, YOff, 16);
+
+            YOff = halfLen + BOff - YOff;
+            BOff += 16;
+        }
+
+        System.arraycopy(Y, 0, B, 0, Y.length);
+    }
+
+    private static void Xor(int[] a, int[] b, int bOff, int[] output)
+    {
+        for (int i = output.length - 1; i >= 0; --i)
+        {
+            output[i] = a[i] ^ b[bOff + i];
+        }
+    }
+
+    private static void Clear(byte[] array)
+    {
+        if (array != null)
+        {
+            Arrays.fill(array, (byte)0);
+        }
+    }
+
+    private static void Clear(int[] array)
+    {
+        if (array != null)
+        {
+            Arrays.fill(array, 0);
+        }
+    }
+
+    private static void ClearAll(int[][] arrays)
+    {
+        for (int i = 0; i < arrays.length; ++i)
+        {
+            Clear(arrays[i]);
+        }
+    }
+}