Patch scrypt implementation to directly use Java's Integer.rotateLeft

This should improve performance in some rare cases where the wrapper
function that BouncyCastle has for Integer.rotateLeft is not inlined.

See: #1024

app/src/main/java/com/beemdevelopment/aegis/crypto/CryptoUtils.java

@@ -2,7 +2,7 @@ package com.beemdevelopment.aegis.crypto;
 
 import android.os.Build;
 
-import org.bouncycastle.crypto.generators.SCrypt;
+import com.beemdevelopment.aegis.crypto.bc.SCrypt;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;

app/src/main/java/com/beemdevelopment/aegis/crypto/bc/SCrypt.java

@@ -0,0 +1,255 @@
+/*
+Copyright (c) 2000-2021 The Legion of the Bouncy Castle Inc. (https://www.bouncycastle.org)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+and associated documentation files (the "Software"), to deal in the Software without restriction,
+including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
+and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial
+portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+ */
+
+package com.beemdevelopment.aegis.crypto.bc;
+
+import org.bouncycastle.crypto.PBEParametersGenerator;
+import org.bouncycastle.crypto.digests.SHA256Digest;
+import org.bouncycastle.crypto.generators.PKCS5S2ParametersGenerator;
+import org.bouncycastle.crypto.params.KeyParameter;
+import org.bouncycastle.util.Arrays;
+import org.bouncycastle.util.Integers;
+import org.bouncycastle.util.Pack;
+
+/**
+ * Implementation of the scrypt a password-based key derivation function.
+ * <p>
+ * Scrypt was created by Colin Percival and is specified in <a
+ * href="https://tools.ietf.org/html/rfc7914">RFC 7914 - The scrypt Password-Based Key Derivation Function</a>
+ */
+public class SCrypt
+{
+    private SCrypt()
+    {
+        // not used.
+    }
+
+    /**
+     * Generate a key using the scrypt key derivation function.
+     *
+     * @param P     the bytes of the pass phrase.
+     * @param S     the salt to use for this invocation.
+     * @param N     CPU/Memory cost parameter. Must be larger than 1, a power of 2 and less than
+     *              <code>2^(128 * r / 8)</code>.
+     * @param r     the block size, must be &gt;= 1.
+     * @param p     Parallelization parameter. Must be a positive integer less than or equal to
+     *              <code>Integer.MAX_VALUE / (128 * r * 8)</code>.
+     * @param dkLen the length of the key to generate.
+     * @return the generated key.
+     */
+    public static byte[] generate(byte[] P, byte[] S, int N, int r, int p, int dkLen)
+    {
+        if (P == null)
+        {
+            throw new IllegalArgumentException("Passphrase P must be provided.");
+        }
+        if (S == null)
+        {
+            throw new IllegalArgumentException("Salt S must be provided.");
+        }
+        if (N <= 1 || !isPowerOf2(N))
+        {
+            throw new IllegalArgumentException("Cost parameter N must be > 1 and a power of 2");
+        }
+        // Only value of r that cost (as an int) could be exceeded for is 1
+        if (r == 1 && N >= 65536)
+        {
+            throw new IllegalArgumentException("Cost parameter N must be > 1 and < 65536.");
+        }
+        if (r < 1)
+        {
+            throw new IllegalArgumentException("Block size r must be >= 1.");
+        }
+        int maxParallel = Integer.MAX_VALUE / (128 * r * 8);
+        if (p < 1 || p > maxParallel)
+        {
+            throw new IllegalArgumentException("Parallelisation parameter p must be >= 1 and <= " + maxParallel
+                    + " (based on block size r of " + r + ")");
+        }
+        if (dkLen < 1)
+        {
+            throw new IllegalArgumentException("Generated key length dkLen must be >= 1.");
+        }
+        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);
+
+            /*
+             * Chunk memory allocations; We choose 'd' so that there will be 2**d chunks, each not
+             * larger than 32KiB, except that the minimum chunk size is 2 * r * 32.
+             */
+            int d = 0, total = N * r;
+            while ((N - d) > 2 && total > (1 << 10))
+            {
+                ++d;
+                total >>>= 1;
+            }
+
+            int MFLenWords = MFLenBytes >>> 2;
+            for (int BOff = 0; BOff < BLen; BOff += MFLenWords)
+            {
+                // TODO These can be done in parallel threads
+                SMix(B, BOff, N, d, 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 d, int r)
+    {
+        int powN = Integers.numberOfTrailingZeros(N);
+        int blocksPerChunk = N >>> d;
+        int chunkCount = 1 << d, chunkMask = blocksPerChunk - 1, chunkPow = powN - d;
+
+        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[][] VV = new int[chunkCount][];
+
+        try
+        {
+            System.arraycopy(B, BOff, X, 0, BCount);
+
+            for (int c = 0; c < chunkCount; ++c)
+            {
+                int[] V = new int[blocksPerChunk * BCount];
+                VV[c] = V;
+
+                int off = 0;
+                for (int i = 0; i < blocksPerChunk; i += 2)
+                {
+                    System.arraycopy(X, 0, V, off, BCount);
+                    off += BCount;
+                    BlockMix(X, blockX1, blockX2, blockY, r);
+                    System.arraycopy(blockY, 0, V, off, BCount);
+                    off += BCount;
+                    BlockMix(blockY, blockX1, blockX2, X, r);
+                }
+            }
+
+            int mask = N - 1;
+            for (int i = 0; i < N; ++i)
+            {
+                int j = X[BCount - 16] & mask;
+                int[] V = VV[j >>> chunkPow];
+                int VOff = (j & chunkMask) * BCount;
+                System.arraycopy(V, VOff, blockY, 0, BCount);
+                Xor(blockY, X, 0, blockY);
+                BlockMix(blockY, blockX1, blockX2, X, r);
+            }
+
+            System.arraycopy(X, 0, B, BOff, BCount);
+        }
+        finally
+        {
+            ClearAll(VV);
+            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;
+        }
+    }
+
+    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]);
+        }
+    }
+
+    // note: we know X is non-zero
+    private static boolean isPowerOf2(int x)
+    {
+        return ((x & (x - 1)) == 0);
+    }
+}

app/src/main/java/com/beemdevelopment/aegis/crypto/bc/Salsa20Engine.java

@@ -0,0 +1,118 @@
+/*
+Copyright (c) 2000-2021 The Legion of the Bouncy Castle Inc. (https://www.bouncycastle.org)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+and associated documentation files (the "Software"), to deal in the Software without restriction,
+including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
+and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial
+portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+ */
+
+package com.beemdevelopment.aegis.crypto.bc;
+
+/**
+ * Implementation of Daniel J. Bernstein's Salsa20 stream cipher, Snuffle 2005
+ */
+public class Salsa20Engine {
+    private Salsa20Engine()
+    {
+
+    }
+
+    public static void salsaCore(int rounds, int[] input, int[] x)
+    {
+        if (input.length != 16)
+        {
+            throw new IllegalArgumentException();
+        }
+        if (x.length != 16)
+        {
+            throw new IllegalArgumentException();
+        }
+        if (rounds % 2 != 0)
+        {
+            throw new IllegalArgumentException("Number of rounds must be even");
+        }
+
+        int x00 = input[ 0];
+        int x01 = input[ 1];
+        int x02 = input[ 2];
+        int x03 = input[ 3];
+        int x04 = input[ 4];
+        int x05 = input[ 5];
+        int x06 = input[ 6];
+        int x07 = input[ 7];
+        int x08 = input[ 8];
+        int x09 = input[ 9];
+        int x10 = input[10];
+        int x11 = input[11];
+        int x12 = input[12];
+        int x13 = input[13];
+        int x14 = input[14];
+        int x15 = input[15];
+
+        for (int i = rounds; i > 0; i -= 2)
+        {
+            x04 ^= Integer.rotateLeft(x00 + x12, 7);
+            x08 ^= Integer.rotateLeft(x04 + x00, 9);
+            x12 ^= Integer.rotateLeft(x08 + x04, 13);
+            x00 ^= Integer.rotateLeft(x12 + x08, 18);
+            x09 ^= Integer.rotateLeft(x05 + x01, 7);
+            x13 ^= Integer.rotateLeft(x09 + x05, 9);
+            x01 ^= Integer.rotateLeft(x13 + x09, 13);
+            x05 ^= Integer.rotateLeft(x01 + x13, 18);
+            x14 ^= Integer.rotateLeft(x10 + x06, 7);
+            x02 ^= Integer.rotateLeft(x14 + x10, 9);
+            x06 ^= Integer.rotateLeft(x02 + x14, 13);
+            x10 ^= Integer.rotateLeft(x06 + x02, 18);
+            x03 ^= Integer.rotateLeft(x15 + x11, 7);
+            x07 ^= Integer.rotateLeft(x03 + x15, 9);
+            x11 ^= Integer.rotateLeft(x07 + x03, 13);
+            x15 ^= Integer.rotateLeft(x11 + x07, 18);
+
+            x01 ^= Integer.rotateLeft(x00 + x03, 7);
+            x02 ^= Integer.rotateLeft(x01 + x00, 9);
+            x03 ^= Integer.rotateLeft(x02 + x01, 13);
+            x00 ^= Integer.rotateLeft(x03 + x02, 18);
+            x06 ^= Integer.rotateLeft(x05 + x04, 7);
+            x07 ^= Integer.rotateLeft(x06 + x05, 9);
+            x04 ^= Integer.rotateLeft(x07 + x06, 13);
+            x05 ^= Integer.rotateLeft(x04 + x07, 18);
+            x11 ^= Integer.rotateLeft(x10 + x09, 7);
+            x08 ^= Integer.rotateLeft(x11 + x10, 9);
+            x09 ^= Integer.rotateLeft(x08 + x11, 13);
+            x10 ^= Integer.rotateLeft(x09 + x08, 18);
+            x12 ^= Integer.rotateLeft(x15 + x14, 7);
+            x13 ^= Integer.rotateLeft(x12 + x15, 9);
+            x14 ^= Integer.rotateLeft(x13 + x12, 13);
+            x15 ^= Integer.rotateLeft(x14 + x13, 18);
+        }
+
+        x[ 0] = x00 + input[ 0];
+        x[ 1] = x01 + input[ 1];
+        x[ 2] = x02 + input[ 2];
+        x[ 3] = x03 + input[ 3];
+        x[ 4] = x04 + input[ 4];
+        x[ 5] = x05 + input[ 5];
+        x[ 6] = x06 + input[ 6];
+        x[ 7] = x07 + input[ 7];
+        x[ 8] = x08 + input[ 8];
+        x[ 9] = x09 + input[ 9];
+        x[10] = x10 + input[10];
+        x[11] = x11 + input[11];
+        x[12] = x12 + input[12];
+        x[13] = x13 + input[13];
+        x[14] = x14 + input[14];
+        x[15] = x15 + input[15];
+    }
+}

app/src/test/java/com/beemdevelopment/aegis/crypto/SCryptTest.java

@@ -1,18 +1,18 @@
 package com.beemdevelopment.aegis.crypto;
 
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertFalse;
+
+import com.beemdevelopment.aegis.crypto.bc.SCrypt;
 import com.beemdevelopment.aegis.encoding.EncodingException;
 import com.beemdevelopment.aegis.encoding.Hex;
 
-import org.bouncycastle.crypto.generators.SCrypt;
 import org.junit.Test;
 
 import java.util.Arrays;
 
 import javax.crypto.SecretKey;
 
-import static org.junit.Assert.assertArrayEquals;
-import static org.junit.Assert.assertFalse;
-
 public class SCryptTest {
     private static class Vector {
         private final byte[] _key;