1 files changed, 182 insertions, 0 deletions
diff --git a/src/main/java/org/pdfbox/encryption/ARCFour.java b/src/main/java/org/pdfbox/encryption/ARCFour.java
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+++ b/src/main/java/org/pdfbox/encryption/ARCFour.java
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+/**
+ * Copyright (c) 2003, www.pdfbox.org
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 3. Neither the name of pdfbox; nor the names of its
+ *    contributors may be used to endorse or promote products derived from this
+ *    software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * http://www.pdfbox.org
+ *
+ */
+package org.pdfbox.encryption;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+/**
+ * This class is an implementation of the alleged RC4 algorithm.
+ *
+ * @author Ben Litchfield
+ * @version $Revision: 1.7 $
+ */
+public class ARCFour
+{
+    private int[] salt;
+    private int b;
+    private int c;
+
+    /**
+     * Constructor.
+     *
+     */
+    public ARCFour()
+    {
+        salt = new int[256];
+    }
+
+    /**
+     * This will reset the key to be used.
+     *
+     * @param key The RC4 key used during encryption.
+    */
+    public void setKey( byte[] key )
+    {
+        b = 0;
+        c = 0;
+
+        if(key.length < 1 || key.length > 32)
+        {
+            throw new IllegalArgumentException("number of bytes must be between 1 and 32");
+        }
+        for(int i = 0; i < salt.length; i++)
+        {
+            salt[i] = i;
+        }
+
+        int keyIndex = 0;
+        int saltIndex = 0;
+        for( int i = 0; i < salt.length; i++)
+        {
+            saltIndex = (fixByte(key[keyIndex]) + salt[i] + saltIndex) % 256;
+            swap( salt, i, saltIndex );
+            keyIndex = (keyIndex + 1) % key.length;
+        }
+
+    }
+
+    /**
+     * Thie will ensure that the value for a byte >=0.
+     *
+     * @param aByte The byte to test against.
+     *
+     * @return A value >=0 and < 256
+     */
+    private static final int fixByte( byte aByte )
+    {
+        return aByte < 0 ? 256 + aByte : aByte;
+    }
+
+    /**
+     * This will swap two values in an array.
+     *
+     * @param data The array to swap from.
+     * @param firstIndex The index of the first element to swap.
+     * @param secondIndex The index of the second element to swap.
+     */
+    private static final void swap( int[] data, int firstIndex, int secondIndex )
+    {
+        int tmp = data[ firstIndex ];
+        data[ firstIndex ] = data[ secondIndex ];
+        data[ secondIndex ] = tmp;
+    }
+
+    /**
+     * This will encrypt and write the next byte.
+     *
+     * @param aByte The byte to encrypt.
+     * @param output The stream to write to.
+     *
+     * @throws IOException If there is an error writing to the output stream.
+     */
+    public void write( byte aByte, OutputStream output ) throws IOException
+    {
+        b = (b + 1) % 256;
+        c = (salt[b] + c) % 256;
+        swap( salt, b, c );
+        int saltIndex = (salt[b] + salt[c]) % 256;
+        output.write(aByte ^ (byte)salt[saltIndex]);
+    }
+
+    /**
+     * This will encrypt and write the data.
+     *
+     * @param data The data to encrypt.
+     * @param output The stream to write to.
+     *
+     * @throws IOException If there is an error writing to the output stream.
+     */
+    public void write( byte[] data, OutputStream output ) throws IOException
+    {
+        for( int i = 0; i < data.length; i++ )
+        {
+            write( data[i], output );
+        }
+    }
+
+    /**
+     * This will encrypt and write the data.
+     *
+     * @param data The data to encrypt.
+     * @param output The stream to write to.
+     *
+     * @throws IOException If there is an error writing to the output stream.
+     */
+    public void write( InputStream data, OutputStream output ) throws IOException
+    {
+        byte[] buffer = new byte[1024];
+        int amountRead = 0;
+        while( (amountRead = data.read( buffer )) != -1 )
+        {
+            write( buffer, 0, amountRead, output );
+        }
+    }
+
+    /**
+     * This will encrypt and write the data.
+     *
+     * @param data The data to encrypt.
+     * @param offset The offset into the array to start reading data from.
+     * @param len The number of bytes to attempt to read.
+     * @param output The stream to write to.
+     *
+     * @throws IOException If there is an error writing to the output stream.
+     */
+    public void write( byte[] data, int offset, int len, OutputStream output) throws IOException
+    {
+        for( int i = offset; i < offset + len; i++ )
+        {
+            write( data[i], output );
+        }
+    }
+}
+\ No newline at end of file