com.helger.security.mac.MacOutputStream Maven / Gradle / Ivy
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/**
* Copyright (C) 2014-2019 Philip Helger (www.helger.com)
* philip[at]helger[dot]com
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.helger.security.mac;
import java.io.IOException;
import java.io.OutputStream;
import javax.annotation.Nonnegative;
import javax.annotation.Nonnull;
import javax.crypto.Mac;
import com.helger.commons.ValueEnforcer;
import com.helger.commons.io.stream.WrappedOutputStream;
import com.helger.commons.string.ToStringGenerator;
/**
* A transparent stream that updates the associated Mac using the bits going
* through the stream.
*
* To complete the Mac computation, call one of the doFinal methods
* on the associated message digest after your calls to one of this digest
* output stream's {@link #write(int) write} methods.
*
* It is possible to turn this stream on or off (see {@link #setOn(boolean)
* on}). When it is on, a call to one of the {@code write} methods results in an
* update on the message digest. But when it is off, the message digest is not
* updated. The default is for the stream to be on.
*
* @author Philip Helger
* @since 9.1.7
*/
public class MacOutputStream extends WrappedOutputStream
{
public static final boolean DEFAULT_ON = true;
/**
* The Mac associated with this stream.
*/
private Mac m_aMac;
private boolean m_bOn = DEFAULT_ON;
/**
* Creates a Mac output stream, using the specified output stream and Mac.
*
* @param aOS
* the output stream.
* @param aMac
* the Mac to associate with this stream.
*/
public MacOutputStream (@Nonnull final OutputStream aOS, @Nonnull final Mac aMac)
{
super (aOS);
setMac (aMac);
}
/**
* Returns the Mac associated with this stream.
*
* @return the Mac associated with this stream.
* @see #setMac(Mac)
*/
@Nonnull
public final Mac getMac ()
{
return m_aMac;
}
/**
* Associates the specified Mac with this stream.
*
* @param aMac
* the Mac to be associated with this stream. May not be
* null.
* @see #getMac()
*/
public final void setMac (@Nonnull final Mac aMac)
{
ValueEnforcer.notNull (aMac, "Mac");
m_aMac = aMac;
}
/**
* Updates the Mac (if the function is on) using the specified byte, and in
* any case writes the byte to the output stream. That is, if the digest
* function is on (see {@link #setOn(boolean) on}), this method calls
* update on the message digest associated with this stream,
* passing it the byte {@code b}. This method then writes the byte to the
* output stream, blocking until the byte is actually written.
*
* @param b
* the byte to be used for updating and writing to the output stream.
* @exception IOException
* if an I/O error occurs.
* @see Mac#update(byte)
*/
@Override
public void write (final int b) throws IOException
{
out.write (b);
if (m_bOn)
{
m_aMac.update ((byte) b);
}
}
/**
* Updates the Mac (if the function is on) using the specified subarray, and
* in any case writes the subarray to the output stream. That is, if the
* digest function is on (see {@link #setOn(boolean) on}), this method calls
* update on the Mac associated with this stream, passing it the
* subarray specifications. This method then writes the subarray bytes to the
* output stream, blocking until the bytes are actually written.
*
* @param aBuf
* the array containing the subarray to be used for updating and
* writing to the output stream.
* @param nOfs
* the offset into {@code b} of the first byte to be updated and
* written.
* @param nLen
* the number of bytes of data to be updated and written from
* {@code b}, starting at offset {@code off}.
* @exception IOException
* if an I/O error occurs.
* @see Mac#update(byte[], int, int)
*/
@Override
public void write (@Nonnull final byte [] aBuf,
@Nonnegative final int nOfs,
@Nonnegative final int nLen) throws IOException
{
out.write (aBuf, nOfs, nLen);
if (m_bOn)
{
m_aMac.update (aBuf, nOfs, nLen);
}
}
/**
* Turns the function on or off. The default is on. When it is on, a call to
* one of the {@code write} methods results in an update on the Mac. But when
* it is off, the Mac is not updated.
*
* @param bOn
* true to turn the function on, false to
* turn it off.
*/
public final void setOn (final boolean bOn)
{
m_bOn = bOn;
}
/**
* @return true if Mac processing is on, false if it
* is off
*/
public final boolean isOn ()
{
return m_bOn;
}
@Override
public String toString ()
{
return ToStringGenerator.getDerived (super.toString ()).append ("Mac", m_aMac).append ("On", m_bOn).getToString ();
}
}