com.braintree.org.bouncycastle.util.encoders.HexEncoder Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of encryption Show documentation
Client side encryption for Braintree integrations on Android.
There is a newer version: 2.1.0
package com.braintree.org.bouncycastle.util.encoders;

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

public class HexEncoder
    implements Encoder
{
    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;
    }
}