package 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;    }}