/*
* @(#)SignatureSpi.java 1.22 06/10/10
*
* Copyright 1990-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program 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.
*
* This program 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 at /legal/license.txt).
*
* 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 Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*
*/
package java.security;
import java.security.spec.AlgorithmParameterSpec;
import java.util.*;
import java.io.*;
/**
* This class defines the <i>Service Provider Interface</i> (<b>SPI</b>)
* for the <code>Signature</code> 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
*
* @version 1.15, 05/03/00
*
* @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;
/**
* 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.
*/
protected abstract byte[] engineSign() throws SignatureException;
/**
* Finishes this signature operation and stores the resulting signature
* bytes in the provided buffer <code>outbuf</code>, starting at
* <code>offset</code>.
* 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</code> 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</code> where the signature is
* stored.
*
* @param len number of bytes within <code>outbuf</code> 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</code>
*
* @exception SignatureException if an error occurs or <code>len</code>
* 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, or the passed-in signature is improperly encoded or
* of the wrong type, 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, or the passed-in signature is improperly encoded or
* of the wrong type, etc.
*/
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</code> 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}.
*
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 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, or null
* if this signature engine does not use any parameters.
*
* <p>The returned parameters may be the same that were used to initialize
* this signature engine, or may contain a combination of default and
* randomly generated parameter values used by the underlying signature
* implementation if this signature engine requires algorithm parameters
* but was not initialized with any.
*
* @return the parameters used with this signature engine, or null if this
* signature engine does not use any parameters
*
* @exception UnsupportedOperationException if this method is
* not overridden by a provider
*/
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 null if
* there is none.
*
* exception InvalidParameterException if <code>param</code> is an
* invalid parameter for this engine, or another exception occurs while
* trying to get this parameter.
*
* 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</code>.
*/
public Object clone() throws CloneNotSupportedException {
if (this instanceof Cloneable) {
return super.clone();
} else {
throw new CloneNotSupportedException();
}
}
}