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package com.trilead.ssh2.crypto;
import java.io.CharArrayWriter;
import java.io.IOException;
/**
* Basic Base64 Support.
*
* @author Christian Plattner, plattner@trilead.com
* @version $Id: Base64.java,v 1.1 2007/10/15 12:49:56 cplattne Exp $
*/
public class Base64
{
static final char[] alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
public static char[] encode(byte[] content)
{
CharArrayWriter cw = new CharArrayWriter((4 * content.length) / 3);
int idx = 0;
int x = 0;
for (int i = 0; i < content.length; i++)
{
if (idx == 0)
x = (content[i] & 0xff) << 16;
else if (idx == 1)
x = x | ((content[i] & 0xff) << 8);
else
x = x | (content[i] & 0xff);
idx++;
if (idx == 3)
{
cw.write(alphabet[x >> 18]);
cw.write(alphabet[(x >> 12) & 0x3f]);
cw.write(alphabet[(x >> 6) & 0x3f]);
cw.write(alphabet[x & 0x3f]);
idx = 0;
}
}
if (idx == 1)
{
cw.write(alphabet[x >> 18]);
cw.write(alphabet[(x >> 12) & 0x3f]);
cw.write('=');
cw.write('=');
}
if (idx == 2)
{
cw.write(alphabet[x >> 18]);
cw.write(alphabet[(x >> 12) & 0x3f]);
cw.write(alphabet[(x >> 6) & 0x3f]);
cw.write('=');
}
return cw.toCharArray();
}
public static byte[] decode(char[] message) throws IOException
{
byte buff[] = new byte[4];
byte dest[] = new byte[message.length];
int bpos = 0;
int destpos = 0;
for (int i = 0; i < message.length; i++)
{
int c = message[i];
if ((c == '\n') || (c == '\r') || (c == ' ') || (c == '\t'))
continue;
if ((c >= 'A') && (c <= 'Z'))
{
buff[bpos++] = (byte) (c - 'A');
}
else if ((c >= 'a') && (c <= 'z'))
{
buff[bpos++] = (byte) ((c - 'a') + 26);
}
else if ((c >= '0') && (c <= '9'))
{
buff[bpos++] = (byte) ((c - '0') + 52);
}
else if (c == '+')
{
buff[bpos++] = 62;
}
else if (c == '/')
{
buff[bpos++] = 63;
}
else if (c == '=')
{
buff[bpos++] = 64;
}
else
{
throw new IOException("Illegal char in base64 code.");
}
if (bpos == 4)
{
bpos = 0;
if (buff[0] == 64)
break;
if (buff[1] == 64)
throw new IOException("Unexpected '=' in base64 code.");
if (buff[2] == 64)
{
int v = (((buff[0] & 0x3f) << 6) | ((buff[1] & 0x3f)));
dest[destpos++] = (byte) (v >> 4);
break;
}
else if (buff[3] == 64)
{
int v = (((buff[0] & 0x3f) << 12) | ((buff[1] & 0x3f) << 6) | ((buff[2] & 0x3f)));
dest[destpos++] = (byte) (v >> 10);
dest[destpos++] = (byte) (v >> 2);
break;
}
else
{
int v = (((buff[0] & 0x3f) << 18) | ((buff[1] & 0x3f) << 12) | ((buff[2] & 0x3f) << 6) | ((buff[3] & 0x3f)));
dest[destpos++] = (byte) (v >> 16);
dest[destpos++] = (byte) (v >> 8);
dest[destpos++] = (byte) (v);
}
}
}
byte[] res = new byte[destpos];
System.arraycopy(dest, 0, res, 0, destpos);
return res;
}
}
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