1 files changed, 85 insertions, 0 deletions
diff --git a/core/src/main/java/org/bouncycastle/crypto/engines/NullEngine.java b/core/src/main/java/org/bouncycastle/crypto/engines/NullEngine.java
new file mode 100644
index 00000000..95a395a4
--- /dev/null
+++ b/core/src/main/java/org/bouncycastle/crypto/engines/NullEngine.java
@@ -0,0 +1,85 @@
+package org.bouncycastle.crypto.engines;
+
+import org.bouncycastle.crypto.BlockCipher;
+import org.bouncycastle.crypto.CipherParameters;
+import org.bouncycastle.crypto.DataLengthException;
+import org.bouncycastle.crypto.OutputLengthException;
+
+/**
+ * The no-op engine that just copies bytes through, irrespective of whether encrypting and decrypting.
+ * Provided for the sake of completeness.
+ */
+public class NullEngine implements BlockCipher
+{
+    private boolean initialised;
+    protected static final int BLOCK_SIZE = 1;
+    
+    /**
+     * Standard constructor.
+     */
+    public NullEngine()
+    {
+        super();
+    }
+
+    /* (non-Javadoc)
+     * @see org.bouncycastle.crypto.BlockCipher#init(boolean, org.bouncycastle.crypto.CipherParameters)
+     */
+    public void init(boolean forEncryption, CipherParameters params) throws IllegalArgumentException
+    {
+        // we don't mind any parameters that may come in
+        this.initialised = true;
+    }
+
+    /* (non-Javadoc)
+     * @see org.bouncycastle.crypto.BlockCipher#getAlgorithmName()
+     */
+    public String getAlgorithmName()
+    {
+        return "Null";
+    }
+
+    /* (non-Javadoc)
+     * @see org.bouncycastle.crypto.BlockCipher#getBlockSize()
+     */
+    public int getBlockSize()
+    {
+        return BLOCK_SIZE;
+    }
+
+    /* (non-Javadoc)
+     * @see org.bouncycastle.crypto.BlockCipher#processBlock(byte[], int, byte[], int)
+     */
+    public int processBlock(byte[] in, int inOff, byte[] out, int outOff)
+        throws DataLengthException, IllegalStateException
+    {
+        if (!initialised)
+        {
+            throw new IllegalStateException("Null engine not initialised");
+        }
+            if ((inOff + BLOCK_SIZE) > in.length)
+            {
+                throw new DataLengthException("input buffer too short");
+            }
+
+            if ((outOff + BLOCK_SIZE) > out.length)
+            {
+                throw new OutputLengthException("output buffer too short");
+            }
+            
+            for (int i = 0; i < BLOCK_SIZE; ++i)
+            {
+                out[outOff + i] = in[inOff + i];
+            }
+            
+            return BLOCK_SIZE;
+    }
+
+    /* (non-Javadoc)
+     * @see org.bouncycastle.crypto.BlockCipher#reset()
+     */
+    public void reset()
+    {
+        // nothing needs to be done
+    }
+}