/**************************************************************************
* Copyright (c) 2001 by Punch Telematix. All rights reserved. *
* *
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* notice, this list of conditions and the following disclaimer. *
* 2. Redistributions in binary form must reproduce the above copyright *
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* documentation and/or other materials provided with the distribution. *
* 3. Neither the name of Punch Telematix nor the names of *
* other contributors may be used to endorse or promote products *
* derived from this software without specific prior written permission.*
* *
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED *
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**************************************************************************/
/*
** $Id: MessageDigestSpi.java,v 1.1.1.1 2004/07/12 14:07:46 cvs Exp $
*/
package java.security;
public abstract class MessageDigestSpi {
public MessageDigestSpi(){}
public Object clone() throws CloneNotSupportedException {
return super.clone();
}
protected abstract byte[] engineDigest();
protected abstract void engineReset();
protected abstract void engineUpdate(byte input);
protected abstract void engineUpdate(byte[] input, int offset, int len);
/**
** method was added in 1.2. It should be abstract, but it cannot be for backworth compatibility.
** Default implementation just calls engineDigest() and copies the result,
** serious providers should override this.
** @param buf buffer in which to write the digest
** @param offset offset within <code>buf</code> where digest should start
** @param len space available to write digest
** @throws DigestException if an arror occurs, in particular if <code>len</code>
** is less than the length of the digest or is out of range.
*/
protected int engineDigest(byte[] buf, int offset, int len) throws DigestException {
if (len < engineGetDigestLength()) {
engineReset();
throw new DigestException("too short");
}
if (offset < 0) {
engineReset();
throw new DigestException("negative offset");
}
if (offset > buf.length - len) {
engineReset();
throw new DigestException("buffer overrun");
}
byte tmp[] = engineDigest();
if (len < tmp.length) {
throw new DigestException("too short");
}
System.arraycopy(tmp, 0, buf, offset, tmp.length);
return tmp.length;
}
/**
** method was added in 1.2. It should be abstract, but it cannot be for backworth compatibility.
** The implementation does nothing. It simply returns 0.
**
** @remark should be overridden
*/
protected int engineGetDigestLength() {
return 0;
}
}