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/* * @(#)DigestOutputStream.java 1.32 05/11/17 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package java.security; import java.io.IOException; import java.io.EOFException; import java.io.OutputStream; import java.io.FilterOutputStream; import java.io.PrintStream; import java.io.ByteArrayOutputStream; /** * A transparent stream that updates the associated message digest using * the bits going through the stream. * * <p>To complete the message digest computation, call one of the * <code>digest</code> methods on the associated message * digest after your calls to one of this digest ouput stream's * {@link #write(int) write} methods. * * <p>It is possible to turn this stream on or off (see * {@link #on(boolean) on}). When it is on, a call to one of the * <code>write</code> 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. * * @see MessageDigest * @see DigestInputStream * * @version 1.32 05/11/17 * @author Benjamin Renaud */ public class DigestOutputStream extends FilterOutputStream { private boolean on = true; /** * The message digest associated with this stream. */ protected MessageDigest digest; /** * Creates a digest output stream, using the specified output stream * and message digest. * * @param stream the output stream. * * @param digest the message digest to associate with this stream. */ public DigestOutputStream(OutputStream stream, MessageDigest digest) { super(stream); setMessageDigest(digest); } /** * Returns the message digest associated with this stream. * * @return the message digest associated with this stream. * @see #setMessageDigest(java.security.MessageDigest) */ public MessageDigest getMessageDigest() { return digest; } /** * Associates the specified message digest with this stream. * * @param digest the message digest to be associated with this stream. * @see #getMessageDigest() */ public void setMessageDigest(MessageDigest digest) { this.digest = digest; } /** * Updates the message digest (if the digest 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 #on(boolean) on}), this method calls * <code>update</code> on the message digest associated with this * stream, passing it the byte <code>b</code>. 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 MessageDigest#update(byte) */ public void write(int b) throws IOException { if (on) { digest.update((byte)b); } out.write(b); } /** * Updates the message digest (if the digest 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 #on(boolean) on}), this method calls <code>update</code> * on the message digest 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 b the array containing the subarray to be used for updating * and writing to the output stream. * * @param off the offset into <code>b</code> of the first byte to * be updated and written. * * @param len the number of bytes of data to be updated and written * from <code>b</code>, starting at offset <code>off</code>. * * @exception IOException if an I/O error occurs. * * @see MessageDigest#update(byte[], int, int) */ public void write(byte[] b, int off, int len) throws IOException { if (on) { digest.update(b, off, len); } out.write(b, off, len); } /** * Turns the digest function on or off. The default is on. When * it is on, a call to one of the <code>write</code> methods results in an * update on the message digest. But when it is off, the message * digest is not updated. * * @param on true to turn the digest function on, false to turn it * off. */ public void on(boolean on) { this.on = on; } /** * Prints a string representation of this digest output stream and * its associated message digest object. */ public String toString() { return "[Digest Output Stream] " + digest.toString(); } }