sdsu.io
Class XorInputStream

java.lang.Object
  |
  +--java.io.InputStream
        |
        +--java.io.FilterInputStream
              |
              +--sdsu.io.XorInputStream

public class XorInputStream

extends java.io.FilterInputStream

XorInputStream is an inputstream that Xor all input bytes with the byte mask given in the constructor. Use to decode output of a XorOutputStream by giving it the XorInputStream the same byte mask as XorOutputStream. XorInputStream and XorOutputStream can be used for a very weak form of encryption.

Version:

1.0 14 Feb 1998

Author:

Roger Whitney (whitney@cs.sdsu.edu)

Constructor Summary

XorInputStream(java.io.InputStream in, byte mask)
Create an XorInputStream on the given input stream.

Method Summary

int	read() Reads the next byte of data and Xors it with the mask given in the constructor.
int	read(byte[] inputBuffer, int offset, int length) Reads up to length bytes of data and Xor each byte.

Methods inherited from class java.io.FilterInputStream

available, close, mark, markSupported, read, reset, skip

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

XorInputStream

public XorInputStream(java.io.InputStream in,
                      byte mask)

Create an XorInputStream on the given input stream.

Parameters:

mask - the bit pattern with which all input bytes will be Xored

Method Detail

read

public int read()
         throws java.io.IOException

Reads the next byte of data and Xors it with the mask given in the constructor. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

Returns:

the next byte of data, or -1 if the end of the stream is reached.

Throws:

java.io.IOException - if an I/O error occurs.

Overrides:

read in class java.io.FilterInputStream

read

public int read(byte[] inputBuffer,
                int offset,
                int length)
         throws java.io.IOException

Reads up to length bytes of data and Xor each byte. This method blocks until some input is available.

Parameters:

inputBuffer - the buffer into which the data is read.

offset - the start offset of the data.

length - the maximum number of bytes read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

java.io.IOException - if an I/O error occurs.

Overrides:

read in class java.io.FilterInputStream