1 files changed, 279 insertions, 0 deletions
diff --git a/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/macs/Poly1305.java b/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/macs/Poly1305.java
new file mode 100644
index 000000000..ca1558d82
--- /dev/null
+++ b/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/macs/Poly1305.java
@@ -0,0 +1,279 @@
+package org.spongycastle.crypto.macs;
+
+import org.spongycastle.crypto.BlockCipher;
+import org.spongycastle.crypto.CipherParameters;
+import org.spongycastle.crypto.DataLengthException;
+import org.spongycastle.crypto.Mac;
+import org.spongycastle.crypto.generators.Poly1305KeyGenerator;
+import org.spongycastle.crypto.params.KeyParameter;
+import org.spongycastle.crypto.params.ParametersWithIV;
+import org.spongycastle.crypto.util.Pack;
+
+/**
+ * Poly1305 message authentication code, designed by D. J. Bernstein.
+ * <p>
+ * Poly1305 computes a 128-bit (16 bytes) authenticator, using a 128 bit nonce and a 256 bit key
+ * consisting of a 128 bit key applied to an underlying cipher, and a 128 bit key (with 106
+ * effective key bits) used in the authenticator.
+ * <p>
+ * The polynomial calculation in this implementation is adapted from the public domain <a
+ * href="https://github.com/floodyberry/poly1305-donna">poly1305-donna-unrolled</a> C implementation
+ * by Andrew M (@floodyberry).
+ * @see Poly1305KeyGenerator
+ */
+public class Poly1305
+    implements Mac
+{
+    private static final int BLOCK_SIZE = 16;
+
+    private final BlockCipher cipher;
+
+    private final byte[] singleByte = new byte[1];
+
+    // Initialised state
+
+    /** Polynomial key */
+    private int r0, r1, r2, r3, r4;
+
+    /** Precomputed 5 * r[1..4] */
+    private int s1, s2, s3, s4;
+
+    /** Encrypted nonce */
+    private int k0, k1, k2, k3;
+
+    // Accumulating state
+
+    /** Current block of buffered input */
+    private final byte[] currentBlock = new byte[BLOCK_SIZE];
+
+    /** Current offset in input buffer */
+    private int currentBlockOffset = 0;
+
+    /** Polynomial accumulator */
+    private int h0, h1, h2, h3, h4;
+
+    /**
+     * Constructs a Poly1305 MAC, using a 128 bit block cipher.
+     */
+    public Poly1305(final BlockCipher cipher)
+    {
+        if (cipher.getBlockSize() != BLOCK_SIZE)
+        {
+            throw new IllegalArgumentException("Poly1305 requires a 128 bit block cipher.");
+        }
+        this.cipher = cipher;
+    }
+
+    /**
+     * Initialises the Poly1305 MAC.
+     *
+     * @param a {@link ParametersWithIV} containing a 128 bit nonce and a {@link KeyParameter} with
+     *            a 256 bit key complying to the {@link Poly1305KeyGenerator Poly1305 key format}.
+     */
+    public void init(final CipherParameters params)
+        throws IllegalArgumentException
+    {
+        final byte[] nonce;
+        final byte[] key;
+        if ((params instanceof ParametersWithIV) && ((ParametersWithIV)params).getParameters() instanceof KeyParameter)
+        {
+            nonce = ((ParametersWithIV)params).getIV();
+            key = ((KeyParameter)((ParametersWithIV)params).getParameters()).getKey();
+        }
+        else
+        {
+            throw new IllegalArgumentException("Poly1305 requires a key and and IV.");
+        }
+
+        setKey(key, nonce);
+        reset();
+    }
+
+    private void setKey(final byte[] key, final byte[] nonce)
+    {
+        if (nonce.length != BLOCK_SIZE)
+        {
+            throw new IllegalArgumentException("Poly1305 requires a 128 bit IV.");
+        }
+        Poly1305KeyGenerator.checkKey(key);
+
+        // Extract r portion of key
+        int t0 = Pack.littleEndianToInt(key, BLOCK_SIZE + 0);
+        int t1 = Pack.littleEndianToInt(key, BLOCK_SIZE + 4);
+        int t2 = Pack.littleEndianToInt(key, BLOCK_SIZE + 8);
+        int t3 = Pack.littleEndianToInt(key, BLOCK_SIZE + 12);
+
+        r0 = t0 & 0x3ffffff; t0 >>>= 26; t0 |= t1 << 6;
+        r1 = t0 & 0x3ffff03; t1 >>>= 20; t1 |= t2 << 12;
+        r2 = t1 & 0x3ffc0ff; t2 >>>= 14; t2 |= t3 << 18;
+        r3 = t2 & 0x3f03fff; t3 >>>= 8;
+        r4 = t3 & 0x00fffff;
+
+        // Precompute multipliers
+        s1 = r1 * 5;
+        s2 = r2 * 5;
+        s3 = r3 * 5;
+        s4 = r4 * 5;
+
+        // Compute encrypted nonce
+        final byte[] cipherKey = new byte[BLOCK_SIZE];
+        System.arraycopy(key, 0, cipherKey, 0, cipherKey.length);
+
+        cipher.init(true, new KeyParameter(cipherKey));
+        cipher.processBlock(nonce, 0, cipherKey, 0);
+
+        k0 = Pack.littleEndianToInt(cipherKey, 0);
+        k1 = Pack.littleEndianToInt(cipherKey, 4);
+        k2 = Pack.littleEndianToInt(cipherKey, 8);
+        k3 = Pack.littleEndianToInt(cipherKey, 12);
+    }
+
+    public String getAlgorithmName()
+    {
+        return "Poly1305-" + cipher.getAlgorithmName();
+    }
+
+    public int getMacSize()
+    {
+        return BLOCK_SIZE;
+    }
+
+    public void update(final byte in)
+        throws IllegalStateException
+    {
+        singleByte[0] = in;
+        update(singleByte, 0, 1);
+    }
+
+    public void update(final byte[] in, final int inOff, final int len)
+        throws DataLengthException,
+        IllegalStateException
+    {
+        int copied = 0;
+        while (len > copied)
+        {
+            if (currentBlockOffset == BLOCK_SIZE)
+            {
+                processBlock();
+                currentBlockOffset = 0;
+            }
+
+            int toCopy = Math.min((len - copied), BLOCK_SIZE - currentBlockOffset);
+            System.arraycopy(in, copied + inOff, currentBlock, currentBlockOffset, toCopy);
+            copied += toCopy;
+            currentBlockOffset += toCopy;
+        }
+
+    }
+
+    private void processBlock()
+    {
+        if (currentBlockOffset < BLOCK_SIZE)
+        {
+            currentBlock[currentBlockOffset] = 1;
+            for (int i = currentBlockOffset + 1; i < BLOCK_SIZE; i++)
+            {
+                currentBlock[i] = 0;
+            }
+        }
+
+        final long t0 = 0xffffffffL & Pack.littleEndianToInt(currentBlock, 0);
+        final long t1 = 0xffffffffL & Pack.littleEndianToInt(currentBlock, 4);
+        final long t2 = 0xffffffffL & Pack.littleEndianToInt(currentBlock, 8);
+        final long t3 = 0xffffffffL & Pack.littleEndianToInt(currentBlock, 12);
+
+        h0 += t0 & 0x3ffffff;
+        h1 += (((t1 << 32) | t0) >>> 26) & 0x3ffffff;
+        h2 += (((t2 << 32) | t1) >>> 20) & 0x3ffffff;
+        h3 += (((t3 << 32) | t2) >>> 14) & 0x3ffffff;
+        h4 += (t3 >>> 8);
+
+        if (currentBlockOffset == BLOCK_SIZE)
+        {
+            h4 += (1 << 24);
+        }
+
+        long tp0 = mul32x32_64(h0,r0) + mul32x32_64(h1,s4) + mul32x32_64(h2,s3) + mul32x32_64(h3,s2) + mul32x32_64(h4,s1);
+        long tp1 = mul32x32_64(h0,r1) + mul32x32_64(h1,r0) + mul32x32_64(h2,s4) + mul32x32_64(h3,s3) + mul32x32_64(h4,s2);
+        long tp2 = mul32x32_64(h0,r2) + mul32x32_64(h1,r1) + mul32x32_64(h2,r0) + mul32x32_64(h3,s4) + mul32x32_64(h4,s3);
+        long tp3 = mul32x32_64(h0,r3) + mul32x32_64(h1,r2) + mul32x32_64(h2,r1) + mul32x32_64(h3,r0) + mul32x32_64(h4,s4);
+        long tp4 = mul32x32_64(h0,r4) + mul32x32_64(h1,r3) + mul32x32_64(h2,r2) + mul32x32_64(h3,r1) + mul32x32_64(h4,r0);
+
+        long b;
+        h0 = (int)tp0 & 0x3ffffff; b = (tp0 >>> 26);
+        tp1 += b; h1 = (int)tp1 & 0x3ffffff; b = ((tp1 >>> 26) & 0xffffffff);
+        tp2 += b; h2 = (int)tp2 & 0x3ffffff; b = ((tp2 >>> 26) & 0xffffffff);
+        tp3 += b; h3 = (int)tp3 & 0x3ffffff; b = (tp3 >>> 26);
+        tp4 += b; h4 = (int)tp4 & 0x3ffffff; b = (tp4 >>> 26);
+        h0 += b * 5;
+    }
+
+    public int doFinal(final byte[] out, final int outOff)
+        throws DataLengthException,
+        IllegalStateException
+    {
+        if (outOff + BLOCK_SIZE > out.length)
+        {
+            throw new DataLengthException("Output buffer is too short.");
+        }
+
+        if (currentBlockOffset > 0)
+        {
+            // Process padded final block
+            processBlock();
+        }
+
+        long f0, f1, f2, f3;
+
+        int b = h0 >>> 26;
+        h0 = h0 & 0x3ffffff;
+        h1 += b; b = h1 >>> 26; h1 = h1 & 0x3ffffff;
+        h2 += b; b = h2 >>> 26; h2 = h2 & 0x3ffffff;
+        h3 += b; b = h3 >>> 26; h3 = h3 & 0x3ffffff;
+        h4 += b; b = h4 >>> 26; h4 = h4 & 0x3ffffff;
+        h0 += b * 5;
+
+        int g0, g1, g2, g3, g4;
+        g0 = h0 + 5; b = g0 >>> 26; g0 &= 0x3ffffff;
+        g1 = h1 + b; b = g1 >>> 26; g1 &= 0x3ffffff;
+        g2 = h2 + b; b = g2 >>> 26; g2 &= 0x3ffffff;
+        g3 = h3 + b; b = g3 >>> 26; g3 &= 0x3ffffff;
+        g4 = h4 + b - (1 << 26);
+
+        b = (g4 >>> 31) - 1;
+        int nb = ~b;
+        h0 = (h0 & nb) | (g0 & b);
+        h1 = (h1 & nb) | (g1 & b);
+        h2 = (h2 & nb) | (g2 & b);
+        h3 = (h3 & nb) | (g3 & b);
+        h4 = (h4 & nb) | (g4 & b);
+
+        f0 = (((h0       ) | (h1 << 26)) & 0xffffffffl) + (0xffffffffL & k0);
+        f1 = (((h1 >>> 6 ) | (h2 << 20)) & 0xffffffffl) + (0xffffffffL & k1);
+        f2 = (((h2 >>> 12) | (h3 << 14)) & 0xffffffffl) + (0xffffffffL & k2);
+        f3 = (((h3 >>> 18) | (h4 << 8 )) & 0xffffffffl) + (0xffffffffL & k3);
+
+        Pack.intToLittleEndian((int)f0, out, outOff);
+        f1 += (f0 >>> 32);
+        Pack.intToLittleEndian((int)f1, out, outOff + 4);
+        f2 += (f1 >>> 32);
+        Pack.intToLittleEndian((int)f2, out, outOff + 8);
+        f3 += (f2 >>> 32);
+        Pack.intToLittleEndian((int)f3, out, outOff + 12);
+
+        reset();
+        return BLOCK_SIZE;
+    }
+
+    public void reset()
+    {
+        currentBlockOffset = 0;
+
+        h0 = h1 = h2 = h3 = h4 = 0;
+    }
+
+    private static final long mul32x32_64(int i1, int i2)
+    {
+        return ((long)i1) * i2;
+    }
+}