2002/03/21 01:19:32

[org.ibex.core.git] / src / org / bouncycastle / crypto / StreamBlockCipher.java

diff --git a/src/org/bouncycastle/crypto/StreamBlockCipher.java b/src/org/bouncycastle/crypto/StreamBlockCipher.java
new file mode 100644 (file)
index 0000000..bea3b6a
--- /dev/null
+++ b/src/org/bouncycastle/crypto/StreamBlockCipher.java
@@ -0,0 +1,108 @@
+package org.bouncycastle.crypto;
+
+/**
+ * a wrapper for block ciphers with a single byte block size, so that they
+ * can be treated like stream ciphers.
+ */
+public class StreamBlockCipher
+    implements StreamCipher
+{
+    private BlockCipher  cipher;
+
+    private byte[]  oneByte = new byte[1];
+
+    /**
+     * basic constructor.
+     *
+     * @param cipher the block cipher to be wrapped.
+     * @exception IllegalArgumentException if the cipher has a block size other than
+     * one.
+     */
+    public StreamBlockCipher(
+        BlockCipher cipher)
+    {
+        if (cipher.getBlockSize() != 1)
+        {
+            throw new IllegalArgumentException("block cipher block size != 1.");
+        }
+
+        this.cipher = cipher;
+    }
+
+    /**
+     * initialise the underlying cipher.
+     *
+     * @param forEncryption true if we are setting up for encryption, false otherwise.
+     * @param param the necessary parameters for the underlying cipher to be initialised.
+     */
+    public void init(
+        boolean forEncryption,
+        CipherParameters params)
+    {
+        cipher.init(forEncryption, params);
+    }
+
+    /**
+     * return the name of the algorithm we are wrapping.
+     *
+     * @return the name of the algorithm we are wrapping.
+     */
+    public String getAlgorithmName()
+    {
+        return cipher.getAlgorithmName();
+    }
+
+    /**
+     * encrypt/decrypt a single byte returning the result.
+     *
+     * @param in the byte to be processed.
+     * @return the result of processing the input byte.
+     */
+    public byte returnByte(
+        byte    in)
+    {
+        oneByte[0] = in;
+
+        cipher.processBlock(oneByte, 0, oneByte, 0);
+
+        return oneByte[0];
+    }
+
+    /**
+     * process a block of bytes from in putting the result into out.
+     * 
+     * @param in the input byte array.
+     * @param inOff the offset into the in array where the data to be processed starts.
+     * @param len the number of bytes to be processed.
+     * @param out the output buffer the processed bytes go into.   
+     * @param outOff the offset into the output byte array the processed data stars at.
+     * @exception DataLengthException if the output buffer is too small.
+     */
+    public void processBytes(
+        byte[]  in,
+        int     inOff,
+        int     len,
+        byte[]  out,
+        int     outOff)
+        throws DataLengthException
+    {
+        if (outOff + len > out.length)
+        {
+            throw new DataLengthException("output buffer too small in processBytes()");
+        }
+
+        for (int i = 0; i != len; i++)
+        {
+                cipher.processBlock(in, inOff + i, out, outOff + i);
+        }
+    }
+
+    /**
+     * reset the underlying cipher. This leaves it in the same state
+     * it was at after the last init (if there was one).
+     */
+    public void reset()
+    {
+        cipher.reset();
+    }
+}