1 files changed, 244 insertions, 0 deletions
diff --git a/core/src/main/java/org/bouncycastle/crypto/io/CipherInputStream.java b/core/src/main/java/org/bouncycastle/crypto/io/CipherInputStream.java
new file mode 100644
index 00000000..bb09a76b
--- /dev/null
+++ b/core/src/main/java/org/bouncycastle/crypto/io/CipherInputStream.java
@@ -0,0 +1,244 @@
+package org.bouncycastle.crypto.io;
+
+import java.io.FilterInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.bouncycastle.crypto.BufferedBlockCipher;
+import org.bouncycastle.crypto.StreamCipher;
+
+/**
+ * A CipherInputStream is composed of an InputStream and a BufferedBlockCipher so
+ * that read() methods return data that are read in from the
+ * underlying InputStream but have been additionally processed by the
+ * Cipher.  The Cipher must be fully initialized before being used by
+ * a CipherInputStream.
+ * <p>
+ * For example, if the Cipher is initialized for decryption, the
+ * CipherInputStream will attempt to read in data and decrypt them,
+ * before returning the decrypted data.
+ */
+public class CipherInputStream
+    extends FilterInputStream
+{
+    private BufferedBlockCipher bufferedBlockCipher;
+    private StreamCipher streamCipher;
+
+    private byte[] buf;
+    private byte[] inBuf;
+
+    private int bufOff;
+    private int maxBuf;
+    private boolean finalized;
+
+    private static final int INPUT_BUF_SIZE = 2048;
+
+    /**
+     * Constructs a CipherInputStream from an InputStream and a
+     * BufferedBlockCipher.
+     */
+    public CipherInputStream(
+        InputStream is,
+        BufferedBlockCipher cipher)
+    {
+        super(is);
+
+        this.bufferedBlockCipher = cipher;
+
+        buf = new byte[cipher.getOutputSize(INPUT_BUF_SIZE)];
+        inBuf = new byte[INPUT_BUF_SIZE];
+    }
+
+    public CipherInputStream(
+        InputStream is,
+        StreamCipher cipher)
+    {
+        super(is);
+
+        this.streamCipher = cipher;
+
+        buf = new byte[INPUT_BUF_SIZE];
+        inBuf = new byte[INPUT_BUF_SIZE];
+    }
+
+    /**
+     * grab the next chunk of input from the underlying input stream
+     */
+    private int nextChunk()
+        throws IOException
+    {
+        int available = super.available();
+
+        // must always try to read 1 byte!
+        // some buggy InputStreams return < 0!
+        if (available <= 0)
+        {
+            available = 1;
+        }
+
+        if (available > inBuf.length)
+        {
+            available = super.read(inBuf, 0, inBuf.length);
+        }
+        else
+        {
+            available = super.read(inBuf, 0, available);
+        }
+
+        if (available < 0)
+        {
+            if (finalized)
+            {
+                return -1;
+            }
+
+            try
+            {
+                if (bufferedBlockCipher != null)
+                {
+                    maxBuf = bufferedBlockCipher.doFinal(buf, 0);
+                }
+                else
+                {
+                    maxBuf = 0; // a stream cipher
+                }
+            }
+            catch (Exception e)
+            {
+                throw new IOException("error processing stream: " + e.toString());
+            }
+
+            bufOff = 0;
+
+            finalized = true;
+
+            if (bufOff == maxBuf)
+            {
+                return -1;
+            }
+        }
+        else
+        {
+            bufOff = 0;
+
+            try
+            {
+                if (bufferedBlockCipher != null)
+                {
+                    maxBuf = bufferedBlockCipher.processBytes(inBuf, 0, available, buf, 0);
+                }
+                else
+                {
+                    streamCipher.processBytes(inBuf, 0, available, buf, 0);
+                    maxBuf = available;
+                }
+            }
+            catch (Exception e)
+            {
+                throw new IOException("error processing stream: " + e.toString());
+            }
+
+            if (maxBuf == 0)    // not enough bytes read for first block...
+            {
+                return nextChunk();
+            }
+        }
+
+        return maxBuf;
+    }
+
+    public int read()
+        throws IOException
+    {
+        if (bufOff == maxBuf)
+        {
+            if (nextChunk() < 0)
+            {
+                return -1;
+            }
+        }
+
+        return buf[bufOff++] & 0xff;
+    }
+
+    public int read(
+        byte[] b)
+        throws IOException
+    {
+        return read(b, 0, b.length);
+    }
+
+    public int read(
+        byte[] b,
+        int off,
+        int len)
+        throws IOException
+    {
+        if (bufOff == maxBuf)
+        {
+            if (nextChunk() < 0)
+            {
+                return -1;
+            }
+        }
+
+        int available = maxBuf - bufOff;
+
+        if (len > available)
+        {
+            System.arraycopy(buf, bufOff, b, off, available);
+            bufOff = maxBuf;
+
+            return available;
+        }
+        else
+        {
+            System.arraycopy(buf, bufOff, b, off, len);
+            bufOff += len;
+
+            return len;
+        }
+    }
+
+    public long skip(
+        long n)
+        throws IOException
+    {
+        if (n <= 0)
+        {
+            return 0;
+        }
+
+        int available = maxBuf - bufOff;
+
+        if (n > available)
+        {
+            bufOff = maxBuf;
+
+            return available;
+        }
+        else
+        {
+            bufOff += (int)n;
+
+            return (int)n;
+        }
+    }
+
+    public int available()
+        throws IOException
+    {
+        return maxBuf - bufOff;
+    }
+
+    public void close()
+        throws IOException
+    {
+        super.close();
+    }
+
+    public boolean markSupported()
+    {
+        return false;
+    }
+}