1 files changed, 174 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/crypto/macs/BlockCipherMac.java b/core/src/main/java/org/spongycastle/crypto/macs/BlockCipherMac.java
new file mode 100644
index 00000000..2446812c
--- /dev/null
+++ b/core/src/main/java/org/spongycastle/crypto/macs/BlockCipherMac.java
@@ -0,0 +1,174 @@
+package org.spongycastle.crypto.macs;
+
+import org.spongycastle.crypto.BlockCipher;
+import org.spongycastle.crypto.CipherParameters;
+import org.spongycastle.crypto.Mac;
+import org.spongycastle.crypto.modes.CBCBlockCipher;
+
+public class BlockCipherMac
+    implements Mac
+{
+    private byte[]          mac;
+
+    private byte[]          buf;
+    private int             bufOff;
+    private BlockCipher     cipher;
+
+    private int             macSize;
+
+    /**
+     * create a standard MAC based on a block cipher. This will produce an
+     * authentication code half the length of the block size of the cipher.
+     *
+     * @param cipher the cipher to be used as the basis of the MAC generation.
+     * @deprecated use CBCBlockCipherMac
+     */
+    public BlockCipherMac(
+        BlockCipher     cipher)
+    {
+        this(cipher, (cipher.getBlockSize() * 8) / 2);
+    }
+
+    /**
+     * create a standard MAC based on a block cipher with the size of the
+     * MAC been given in bits.
+     * <p>
+     * Note: the size of the MAC must be at least 16 bits (FIPS Publication 113),
+     * and in general should be less than the size of the block cipher as it reduces
+     * the chance of an exhaustive attack (see Handbook of Applied Cryptography).
+     *
+     * @param cipher the cipher to be used as the basis of the MAC generation.
+     * @param macSizeInBits the size of the MAC in bits, must be a multiple of 8.
+     * @deprecated use CBCBlockCipherMac
+     */
+    public BlockCipherMac(
+        BlockCipher     cipher,
+        int             macSizeInBits)
+    {
+        if ((macSizeInBits % 8) != 0)
+        {
+            throw new IllegalArgumentException("MAC size must be multiple of 8");
+        }
+
+        this.cipher = new CBCBlockCipher(cipher);
+        this.macSize = macSizeInBits / 8;
+
+        mac = new byte[cipher.getBlockSize()];
+
+        buf = new byte[cipher.getBlockSize()];
+        bufOff = 0;
+    }
+
+    public String getAlgorithmName()
+    {
+        return cipher.getAlgorithmName();
+    }
+
+    public void init(
+        CipherParameters    params)
+    {
+        reset();
+
+        cipher.init(true, params);
+    }
+
+    public int getMacSize()
+    {
+        return macSize;
+    }
+
+    public void update(
+        byte        in)
+    {
+        if (bufOff == buf.length)
+        {
+            cipher.processBlock(buf, 0, mac, 0);
+            bufOff = 0;
+        }
+
+        buf[bufOff++] = in;
+    }
+
+    public void update(
+        byte[]      in,
+        int         inOff,
+        int         len)
+    {
+        if (len < 0)
+        {
+            throw new IllegalArgumentException("Can't have a negative input length!");
+        }
+
+        int blockSize = cipher.getBlockSize();
+        int resultLen = 0;
+        int gapLen = blockSize - bufOff;
+
+        if (len > gapLen)
+        {
+            System.arraycopy(in, inOff, buf, bufOff, gapLen);
+
+            resultLen += cipher.processBlock(buf, 0, mac, 0);
+
+            bufOff = 0;
+            len -= gapLen;
+            inOff += gapLen;
+
+            while (len > blockSize)
+            {
+                resultLen += cipher.processBlock(in, inOff, mac, 0);
+
+                len -= blockSize;
+                inOff += blockSize;
+            }
+        }
+
+        System.arraycopy(in, inOff, buf, bufOff, len);
+
+        bufOff += len;
+    }
+
+    public int doFinal(
+        byte[]  out,
+        int     outOff)
+    {
+        int blockSize = cipher.getBlockSize();
+
+        //
+        // pad with zeroes
+        //
+        while (bufOff < blockSize)
+        {
+            buf[bufOff] = 0;
+            bufOff++;
+        }
+
+        cipher.processBlock(buf, 0, mac, 0);
+
+        System.arraycopy(mac, 0, out, outOff, macSize);
+
+        reset();
+
+        return macSize;
+    }
+
+    /**
+     * Reset the mac generator.
+     */
+    public void reset()
+    {
+        /*
+         * clean the buffer.
+         */
+        for (int i = 0; i < buf.length; i++)
+        {
+            buf[i] = 0;
+        }
+
+        bufOff = 0;
+
+        /*
+         * reset the underlying cipher.
+         */
+        cipher.reset();
+    }
+}