HexEncoder.java

package kellinwood.security.zipsigner;

/*
This file is a copy of org.bouncycastle.util.encoders.HexEncoder.
  
Please note: our license is an adaptation of the MIT X11 License and should be read as such.
License

Copyright (c) 2000 - 2011 The Legion Of The Bouncy Castle (http://www.bouncycastle.org)

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

*/

import java.io.IOException;
import java.io.OutputStream;

public class HexEncoder
{
    protected final byte[] encodingTable =
        {
            (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5', (byte)'6', (byte)'7',
            (byte)'8', (byte)'9', (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f'
        };
    
    /*
     * set up the decoding table.
     */
    protected final byte[] decodingTable = new byte[128];

    protected void initialiseDecodingTable()
    {
        for (int i = 0; i < encodingTable.length; i++)
        {
            decodingTable[encodingTable[i]] = (byte)i;
        }
        
        decodingTable['A'] = decodingTable['a'];
        decodingTable['B'] = decodingTable['b'];
        decodingTable['C'] = decodingTable['c'];
        decodingTable['D'] = decodingTable['d'];
        decodingTable['E'] = decodingTable['e'];
        decodingTable['F'] = decodingTable['f'];
    }
    
    public HexEncoder()
    {
        initialiseDecodingTable();
    }
    
    /**
     * encode the input data producing a Hex output stream.
     *
     * @return the number of bytes produced.
     */
    public int encode(
        byte[]                data,
        int                    off,
        int                    length,
        OutputStream    out) 
        throws IOException
    {        
        for (int i = off; i < (off + length); i++)
        {
            int    v = data[i] & 0xff;

            out.write(encodingTable[(v >>> 4)]);
            out.write(encodingTable[v & 0xf]);
        }

        return length * 2;
    }

    private boolean ignore(
        char    c)
    {
        return (c == '\n' || c =='\r' || c == '\t' || c == ' ');
    }
    
    /**
     * decode the Hex encoded byte data writing it to the given output stream,
     * whitespace characters will be ignored.
     *
     * @return the number of bytes produced.
     */
    public int decode(
        byte[]          data,
        int             off,
        int             length,
        OutputStream    out)
        throws IOException
    {
        byte    b1, b2;
        int     outLen = 0;
        
        int     end = off + length;
        
        while (end > off)
        {
            if (!ignore((char)data[end - 1]))
            {
                break;
            }
            
            end--;
        }
        
        int i = off;
        while (i < end)
        {
            while (i < end && ignore((char)data[i]))
            {
                i++;
            }
            
            b1 = decodingTable[data[i++]];
            
            while (i < end && ignore((char)data[i]))
            {
                i++;
            }
            
            b2 = decodingTable[data[i++]];

            out.write((b1 << 4) | b2);
            
            outLen++;
        }

        return outLen;
    }
    
    /**
     * decode the Hex encoded String data writing it to the given output stream,
     * whitespace characters will be ignored.
     *
     * @return the number of bytes produced.
     */
    public int decode(
        String          data,
        OutputStream    out)
        throws IOException
    {
        byte    b1, b2;
        int     length = 0;
        
        int     end = data.length();
        
        while (end > 0)
        {
            if (!ignore(data.charAt(end - 1)))
            {
                break;
            }
            
            end--;
        }
        
        int i = 0;
        while (i < end)
        {
            while (i < end && ignore(data.charAt(i)))
            {
                i++;
            }
            
            b1 = decodingTable[data.charAt(i++)];
            
            while (i < end && ignore(data.charAt(i)))
            {
                i++;
            }
            
            b2 = decodingTable[data.charAt(i++)];

            out.write((b1 << 4) | b2);
            
            length++;
        }

        return length;
    }
}