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	/*
	* Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.security;

	import java.security.spec.AlgorithmParameterSpec;
	import java.util.*;
	import java.io.*;

	import java.nio.ByteBuffer;

	import sun.security.jca.JCAUtil;

	/**
	* This class defines the <i>Service Provider Interface</i> (<b>SPI</b>)
	* for the {@code Signature} class, which is used to provide the
	* functionality of a digital signature algorithm. Digital signatures are used
	* for authentication and integrity assurance of digital data.
	*
	* <p> All the abstract methods in this class must be implemented by each
	* cryptographic service provider who wishes to supply the implementation
	* of a particular signature algorithm.
	*
	* @author Benjamin Renaud
	* @since 1.2
	*
	*
	* @see Signature
	*/

	public abstract class SignatureSpi {

	/**
	* Application-specified source of randomness.
	*/
	protected SecureRandom appRandom = null;

	/**
	* Initializes this signature object with the specified
	* public key for verification operations.
	*
	* @param publicKey the public key of the identity whose signature is
	* going to be verified.
	*
	* @exception InvalidKeyException if the key is improperly
	* encoded, parameters are missing, and so on.
	*/
	protected abstract void engineInitVerify(PublicKey publicKey)
	throws InvalidKeyException;

	/**
	* Initializes this signature object with the specified
	* private key for signing operations.
	*
	* @param privateKey the private key of the identity whose signature
	* will be generated.
	*
	* @exception InvalidKeyException if the key is improperly
	* encoded, parameters are missing, and so on.
	*/
	protected abstract void engineInitSign(PrivateKey privateKey)
	throws InvalidKeyException;

	/**
	* Initializes this signature object with the specified
	* private key and source of randomness for signing operations.
	*
	* <p>This concrete method has been added to this previously-defined
	* abstract class. (For backwards compatibility, it cannot be abstract.)
	*
	* @param privateKey the private key of the identity whose signature
	* will be generated.
	* @param random the source of randomness
	*
	* @exception InvalidKeyException if the key is improperly
	* encoded, parameters are missing, and so on.
	*/
	protected void engineInitSign(PrivateKey privateKey,
	SecureRandom random)
	throws InvalidKeyException {
	this.appRandom = random;
	engineInitSign(privateKey);
	}

	/**
	* Updates the data to be signed or verified
	* using the specified byte.
	*
	* @param b the byte to use for the update.
	*
	* @exception SignatureException if the engine is not initialized
	* properly.
	*/
	protected abstract void engineUpdate(byte b) throws SignatureException;

	/**
	* Updates the data to be signed or verified, using the
	* specified array of bytes, starting at the specified offset.
	*
	* @param b the array of bytes
	* @param off the offset to start from in the array of bytes
	* @param len the number of bytes to use, starting at offset
	*
	* @exception SignatureException if the engine is not initialized
	* properly
	*/
	protected abstract void engineUpdate(byte[] b, int off, int len)
	throws SignatureException;

	/**
	* Updates the data to be signed or verified using the specified
	* ByteBuffer. Processes the {@code data.remaining()} bytes
	* starting at {@code data.position()}.
	* Upon return, the buffer's position will be equal to its limit;
	* its limit will not have changed.
	*
	* @param input the ByteBuffer
	* @since 1.5
	*/
	protected void engineUpdate(ByteBuffer input) {
	if (input.hasRemaining() == false) {
	return;
	}
	try {
	if (input.hasArray()) {
	byte[] b = input.array();
	int ofs = input.arrayOffset();
	int pos = input.position();
	int lim = input.limit();
	engineUpdate(b, ofs + pos, lim - pos);
	input.position(lim);
	} else {
	int len = input.remaining();
	byte[] b = new byte[JCAUtil.getTempArraySize(len)];
	while (len > 0) {
	int chunk = Math.min(len, b.length);
	input.get(b, 0, chunk);
	engineUpdate(b, 0, chunk);
	len -= chunk;
	}
	}
	} catch (SignatureException e) {
	// is specified to only occur when the engine is not initialized
	// this case should never occur as it is caught in Signature.java
	throw new ProviderException("update() failed", e);
	}
	}

	/**
	* Returns the signature bytes of all the data
	* updated so far.
	* The format of the signature depends on the underlying
	* signature scheme.
	*
	* @return the signature bytes of the signing operation's result.
	*
	* @exception SignatureException if the engine is not
	* initialized properly or if this signature algorithm is unable to
	* process the input data provided.
	*/
	protected abstract byte[] engineSign() throws SignatureException;

	/**
	* Finishes this signature operation and stores the resulting signature
	* bytes in the provided buffer {@code outbuf}, starting at
	* {@code offset}.
	* The format of the signature depends on the underlying
	* signature scheme.
	*
	* <p>The signature implementation is reset to its initial state
	* (the state it was in after a call to one of the
	* {@code engineInitSign} methods)
	* and can be reused to generate further signatures with the same private
	* key.
	*
	* This method should be abstract, but we leave it concrete for
	* binary compatibility. Knowledgeable providers should override this
	* method.
	*
	* @param outbuf buffer for the signature result.
	*
	* @param offset offset into {@code outbuf} where the signature is
	* stored.
	*
	* @param len number of bytes within {@code outbuf} allotted for the
	* signature.
	* Both this default implementation and the SUN provider do not
	* return partial digests. If the value of this parameter is less
	* than the actual signature length, this method will throw a
	* SignatureException.
	* This parameter is ignored if its value is greater than or equal to
	* the actual signature length.
	*
	* @return the number of bytes placed into {@code outbuf}
	*
	* @exception SignatureException if the engine is not
	* initialized properly, if this signature algorithm is unable to
	* process the input data provided, or if {@code len} is less
	* than the actual signature length.
	*
	* @since 1.2
	*/
	protected int engineSign(byte[] outbuf, int offset, int len)
	throws SignatureException {
	byte[] sig = engineSign();
	if (len < sig.length) {
	throw new SignatureException
	("partial signatures not returned");
	}
	if (outbuf.length - offset < sig.length) {
	throw new SignatureException
	("insufficient space in the output buffer to store the "
	+ "signature");
	}
	System.arraycopy(sig, 0, outbuf, offset, sig.length);
	return sig.length;
	}

	/**
	* Verifies the passed-in signature.
	*
	* @param sigBytes the signature bytes to be verified.
	*
	* @return true if the signature was verified, false if not.
	*
	* @exception SignatureException if the engine is not
	* initialized properly, the passed-in signature is improperly
	* encoded or of the wrong type, if this signature algorithm is unable to
	* process the input data provided, etc.
	*/
	protected abstract boolean engineVerify(byte[] sigBytes)
	throws SignatureException;

	/**
	* Verifies the passed-in signature in the specified array
	* of bytes, starting at the specified offset.
	*
	* <p> Note: Subclasses should overwrite the default implementation.
	*
	*
	* @param sigBytes the signature bytes to be verified.
	* @param offset the offset to start from in the array of bytes.
	* @param length the number of bytes to use, starting at offset.
	*
	* @return true if the signature was verified, false if not.
	*
	* @exception SignatureException if the engine is not
	* initialized properly, the passed-in signature is improperly
	* encoded or of the wrong type, if this signature algorithm is unable to
	* process the input data provided, etc.
	* @since 1.4
	*/
	protected boolean engineVerify(byte[] sigBytes, int offset, int length)
	throws SignatureException {
	byte[] sigBytesCopy = new byte[length];
	System.arraycopy(sigBytes, offset, sigBytesCopy, 0, length);
	return engineVerify(sigBytesCopy);
	}

	/**
	* Sets the specified algorithm parameter to the specified
	* value. This method supplies a general-purpose mechanism through
	* which it is possible to set the various parameters of this object.
	* A parameter may be any settable parameter for the algorithm, such as
	* a parameter size, or a source of random bits for signature generation
	* (if appropriate), or an indication of whether or not to perform
	* a specific but optional computation. A uniform algorithm-specific
	* naming scheme for each parameter is desirable but left unspecified
	* at this time.
	*
	* @param param the string identifier of the parameter.
	*
	* @param value the parameter value.
	*
	* @exception InvalidParameterException if {@code param} is an
	* invalid parameter for this signature algorithm engine,
	* the parameter is already set
	* and cannot be set again, a security exception occurs, and so on.
	*
	* @deprecated Replaced by {@link
	* #engineSetParameter(java.security.spec.AlgorithmParameterSpec)
	* engineSetParameter}.
	*/
	@Deprecated
	protected abstract void engineSetParameter(String param, Object value)
	throws InvalidParameterException;

	/**
	* <p>This method is overridden by providers to initialize
	* this signature engine with the specified parameter set.
	*
	* @param params the parameters
	*
	* @exception UnsupportedOperationException if this method is not
	* overridden by a provider
	*
	* @exception InvalidAlgorithmParameterException if this method is
	* overridden by a provider and the given parameters
	* are inappropriate for this signature engine
	*/
	protected void engineSetParameter(AlgorithmParameterSpec params)
	throws InvalidAlgorithmParameterException {
	throw new UnsupportedOperationException();
	}

	/**
	* <p>This method is overridden by providers to return the parameters
	* used with this signature engine.
	*
	* <p> If this signature engine has been previously initialized with
	* parameters (by calling the {@code engineSetParameter} method), this
	* method returns the same parameters. If this signature engine has not been
	* initialized with parameters, this method may return a combination of
	* default and randomly generated parameter values if the underlying
	* signature implementation supports it and can successfully generate
	* them. Otherwise, {@code null} is returned.
	*
	* @return the parameters used with this signature engine, or {@code null}
	*
	* @exception UnsupportedOperationException if this method is
	* not overridden by a provider
	* @since 1.4
	*/
	protected AlgorithmParameters engineGetParameters() {
	throw new UnsupportedOperationException();
	}

	/**
	* Gets the value of the specified algorithm parameter.
	* This method supplies a general-purpose mechanism through which it
	* is possible to get the various parameters of this object. A parameter
	* may be any settable parameter for the algorithm, such as a parameter
	* size, or a source of random bits for signature generation (if
	* appropriate), or an indication of whether or not to perform a
	* specific but optional computation. A uniform algorithm-specific
	* naming scheme for each parameter is desirable but left unspecified
	* at this time.
	*
	* @param param the string name of the parameter.
	*
	* @return the object that represents the parameter value, or {@code null} if
	* there is none.
	*
	* @exception InvalidParameterException if {@code param} is an
	* invalid parameter for this engine, or another exception occurs while
	* trying to get this parameter.
	*
	* @deprecated
	*/
	@Deprecated
	protected abstract Object engineGetParameter(String param)
	throws InvalidParameterException;

	/**
	* Returns a clone if the implementation is cloneable.
	*
	* @return a clone if the implementation is cloneable.
	*
	* @exception CloneNotSupportedException if this is called
	* on an implementation that does not support {@code Cloneable}.
	*/
	public Object clone() throws CloneNotSupportedException {
	if (this instanceof Cloneable) {
	return super.clone();
	} else {
	throw new CloneNotSupportedException();
	}
	}
	}

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