mediaframe.mpeg1
Class CryptedInputStream

java.lang.Object
  |
  +--java.io.InputStream
        |
        +--java.io.FilterInputStream
              |
              +--mediaframe.mpeg1.CryptedInputStream

public final class CryptedInputStream

extends java.io.FilterInputStream

The CryptedInputStream class implements decryption function of the MPEG stream.

Field Summary

private int	encryption_index The current index in the encryption key.
private byte[]	encryption_key The array of bytes (encryption key) which are used for encription of the movie stream.

Fields inherited from class java.io.FilterInputStream

in

Fields inherited from class java.io.InputStream

Constructor Summary

CryptedInputStream(java.io.InputStream in)
Constructor of the CryptedInputStream class.

Method Summary

int	read() Reads one byte from the input stream and decrypts it using xor 0x55 operation.
int	read(byte[] b) Reads n bytes from the input stream into the buffer b and decrypts them using xor 0x55 operation
int	read(byte[] b, int off, int len) Reads len bytes from the input stream into the buffer b starting from the offset off and decrypts them using xor 0x55 operation

Methods inherited from class java.io.FilterInputStream

available, close, mark, markSupported, reset, skip

Methods inherited from class java.lang.Object

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

Field Detail

encryption_index

private int encryption_index

The current index in the encryption key.

encryption_key

private byte[] encryption_key

The array of bytes (encryption key) which are used for encription of the movie stream.

Constructor Detail

CryptedInputStream

public CryptedInputStream(java.io.InputStream in)
                   throws java.lang.Exception

Constructor of the CryptedInputStream class.

Parameters:

in - the MPEG input stream which is decrypted.

Throws:

java.lang.Exception - raises if an error occurs during initialization.

Method Detail

read

public int read()
         throws java.io.IOException

Reads one byte from the input stream and decrypts it using xor 0x55 operation.

Overrides:

read in class java.io.FilterInputStream

Returns:

readed and decrypted byte.

Throws:

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

read

public int read(byte[] b)
         throws java.io.IOException

Reads n bytes from the input stream into the buffer b and decrypts them using xor 0x55 operation

Overrides:

read in class java.io.FilterInputStream

Parameters:

b - the buffer into which the data is read.

Returns:

the number of bytes read into the buffer or -1 if the end of the file is reached.

Throws:

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

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException

Reads len bytes from the input stream into the buffer b starting from the offset off and decrypts them using xor 0x55 operation

Overrides:

read in class java.io.FilterInputStream

Parameters:

b - the buffer into which the data is read.

off - the start offset in the array b.

len - the number of the bytes to read.

Returns:

the number of bytes read into the buffer or -1 if the end of the file is reached.

Throws:

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