new MultiBlockCipher interface.

core/src/main/java/org/bouncycastle/crypto/DefaultMultiBlockCipher.java

@@ -0,0 +1,33 @@
+package org.bouncycastle.crypto;
+
+public abstract class DefaultMultiBlockCipher
+    implements MultiBlockCipher
+{
+    protected DefaultMultiBlockCipher()
+    {
+    }
+
+    public int getMultiBlockSize()
+    {
+        return this.getBlockSize();
+    }
+
+    public int processBlocks(byte[] in, int inOff, int blockCount, byte[] out, int outOff)
+        throws DataLengthException, IllegalStateException
+    {
+
+        // TODO check if the underlying cipher supports the multiblock interface and call it directly?
+
+        int resultLen = 0;
+        int blockSize = this.getMultiBlockSize();
+
+        for (int i = 0; i != blockCount; i++)
+        {
+            resultLen += this.processBlock(in, inOff, out, outOff + resultLen);
+
+            inOff += blockSize;
+        }
+
+        return resultLen;
+    }
+}

core/src/main/java/org/bouncycastle/crypto/MultiBlockCipher.java

@@ -0,0 +1,31 @@
+package org.bouncycastle.crypto;
+
+/**
+ * Base interface for a cipher engine capable of processing multiple blocks at a time.
+ */
+public interface MultiBlockCipher
+    extends BlockCipher
+{
+    /**
+     * Return the multi-block size for this cipher (in bytes).
+     *
+     * @return the multi-block size for this cipher in bytes.
+     */
+    int getMultiBlockSize();
+
+    /**
+     * Process blockCount blocks from input in offset inOff and place the output in
+     * out from offset outOff.
+     *
+     * @param in input data array.
+     * @param inOff start of input data in in.
+     * @param blockCount number of blocks to be processed.
+     * @param out output data array.
+     * @param outOff start position for output data.
+     * @return number of bytes written to out.
+     * @throws DataLengthException
+     * @throws IllegalStateException
+     */
+    int processBlocks(byte[] in, int inOff, int blockCount, byte[] out, int outOff)
+        throws DataLengthException, IllegalStateException;
+}

core/src/main/java/org/bouncycastle/crypto/StreamBlockCipher.java

@@ -5,7 +5,8 @@
  * a streaming mode.
  */
 public abstract class StreamBlockCipher
-    implements BlockCipher, StreamCipher
+    extends DefaultMultiBlockCipher
+    implements StreamCipher
 {
     private final BlockCipher cipher;