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gnu.javax.crypto.mac

Class MacInputStream

Implemented Interfaces:
AutoCloseable, Closeable
public class MacInputStream
extends FilterInputStream
A filtering input stream that computes a MAC (message authentication code) over all data read from the stream.

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

MacInputStream(InputStream in, IMac mac)
Creates a new MacInputStream.

Method Summary

IMac
getMac()
Returns the MAC this stream is updating.
void
on(boolean flag)
Turns the digesting state on or off.
int
read()
This method reads an unsigned byte from the input stream and returns it as an int in the range of 0-255.
int
read(byte[] buf, int off, int len)
This method read bytes from a stream and stores them into a caller supplied buffer.
void
setMac(IMac mac)
Sets the MAC this stream is updating, which must have already been initialized.

Methods inherited from class java.io.FilterInputStream

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

Methods inherited from class java.io.InputStream

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

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

MacInputStream

public MacInputStream(InputStream in,
                      IMac mac)
Creates a new MacInputStream. The stream is initially set to digest data written, the mac argument must have already been initialized, and the mac argument is not cloned.
Parameters:
in - The underlying input stream.
mac - The mac instance to use.

Method Details

getMac

public IMac getMac()
Returns the MAC this stream is updating.
Returns:
The MAC.

on

public void on(boolean flag)
Turns the digesting state on or off. When off, the MAC will not be updated when data is written to the stream.
Parameters:
flag - The new digesting state.

read

public int read()
            throws IOException
This method reads an unsigned byte from the input stream and returns it as an int in the range of 0-255. This method also will return -1 if the end of the stream has been reached.

This method will block until the byte can be read.

Overrides:
read in interface FilterInputStream
Returns:
The byte read or -1 if end of stream
Throws:
IOException - If an error occurs

read

public int read(byte[] buf,
                int off,
                int len)
            throws IOException
This method read bytes from a stream and stores them into a caller supplied buffer. It starts storing the data at index off into the buffer and attempts to read len bytes. This method can return before reading the number of bytes requested. The actual number of bytes read is returned as an int. A -1 is returned to indicate the end of the stream.

This method will block until some data can be read.

This method operates by calling the single byte read() method in a loop until the desired number of bytes are read. The read loop stops short if the end of the stream is encountered or if an IOException is encountered on any read operation except the first. If the first attempt to read a bytes fails, the IOException is allowed to propagate upward. And subsequent IOException is caught and treated identically to an end of stream condition. Subclasses can (and should if possible) override this method to provide a more efficient implementation.

Overrides:
read in interface FilterInputStream
Parameters:
off - The offset into the array to start storing bytes
len - The requested number of bytes to read
Returns:
The actual number of bytes read, or -1 if end of stream.
Throws:
IOException - If an error occurs.

setMac

public void setMac(IMac mac)
Sets the MAC this stream is updating, which must have already been initialized. The argument is not cloned by this method.
Parameters:
mac - The new MAC.
Throws:
NullPointerException - If the argument is null.
MacInputStream.java -- Copyright (C) 2003, 2006 Free Software Foundation, Inc. This file is a part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.

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