/* Signature.java --- Signature Class Copyright (C) 1999, 2002, 2003 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath 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 for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version. */ package java.security; import java.security.cert.Certificate; import java.security.cert.X509Certificate; import java.security.spec.AlgorithmParameterSpec; import gnu.java.security.Engine; /** *
This Signature
class is used to provide applications the
* functionality of a digital signature algorithm. Digital signatures are used
* for authentication and integrity assurance of digital data.
The signature algorithm can be, among others, the NIST standard DSS,
* using DSA and SHA-1. The DSA algorithm using the
* SHA-1 message digest algorithm can be specified as SHA1withDSA
*
. In the case of RSA, there are multiple choices for the
* message digest algorithm, so the signing algorithm could be specified as, for
* example, MD2withRSA
, MD5withRSA
, or
* SHA1withRSA
. The algorithm name must be specified, as there is
* no default.
Like other algorithm-based classes in Java Security, Signature
* provides implementation-independent algorithms, whereby a caller (application
* code) requests a particular signature algorithm and is handed back a properly
* initialized Signature
object. It is also possible, if desired,
* to request a particular algorithm from a particular provider. See the
* getInstance()
methods.
Thus, there are two ways to request a Signature
algorithm
* object: by specifying either just an algorithm name, or both an algorithm
* name and a package provider.
If just an algorithm name is specified, the system will determine if there * is an implementation of the algorithm requested available in the environment, * and if there is more than one, if there is a preferred one.
* *If both an algorithm name and a package provider are specified, the system * will determine if there is an implementation of the algorithm in the package * requested, and throw an exception if there is not.
* *A Signature
object can be used to generate and verify digital
* signatures.
There are three phases to the use of a Signature
object for
* either signing data or verifying a signature:
initVerify()
), orsign()
methods and the verify()
method.Note that this class is abstract and extends from {@link SignatureSpi} for
* historical reasons. Application developers should only take notice of the
* methods defined in this Initializes this object for verification, using the public key from the
* given certificate. If the certificate is of type X.509 and has a key usage
* extension field marked as critical, and the value of the key
* usage extension field implies that the public key in the certificate
* and its corresponding private key are not supposed to be used for digital
* signatures, an {@link InvalidKeyException} is thrown. Returns the signature bytes of all the data updated. The format of the
* signature depends on the underlying signature scheme. A call to this method resets this signature object to the state it was
* in when previously initialized for signing via a call to
* Finishes the signature operation and stores the resulting signature
* bytes in the provided buffer This signature object is reset to its initial state (the state it was
* in after a call to one of the Verifies the passed-in signature. A call to this method resets this signature object to the state it was
* in when previously initialized for verification via a call to
* Verifies the passed-in A call to this method resets this signature object to the state it was
* in when previously initialized for verification via a call to
* Returns the parameters used with this signature object. The returned parameters may be the same that were used to initialize
* this signature, or may contain a combination of default and randomly
* generated parameter values used by the underlying signature implementation
* if this signature requires algorithm parameters but was not initialized
* with any.
*
* @return the parameters used with this signature, or Signature
class; all the methods in the
* superclass are intended for cryptographic service providers who wish to
* supply their own implementations of digital signature algorithms.
*
* @author Mark Benvenuto state
value, signifying that this signature object
* has not yet been initialized.
*/
protected static final int UNINITIALIZED = 0;
// Constructor.
// ------------------------------------------------------------------------
/**
* Possible state
value, signifying that this signature object
* has been initialized for signing.
*/
protected static final int SIGN = 2;
/**
* Possible state
value, signifying that this signature object
* has been initialized for verification.
*/
protected static final int VERIFY = 3;
/** Current state of this signature object. */
protected int state = UNINITIALIZED;
private String algorithm;
Provider provider;
/**
* Creates a Signature
object for the specified algorithm.
*
* @param algorithm the standard string name of the algorithm. See Appendix A
* in the Java Cryptography Architecture API Specification & Reference for
* information about standard algorithm names.
*/
protected Signature(String algorithm)
{
this.algorithm = algorithm;
state = UNINITIALIZED;
}
/**
* Generates a Signature
object that implements the specified
* digest algorithm. If the default provider package provides an
* implementation of the requested digest algorithm, an instance of
* Signature
containing that implementation is returned. If the
* algorithm is not available in the default package, other packages are
* searched.
*
* @param algorithm the standard name of the algorithm requested. See Appendix
* A in the Java Cryptography Architecture API Specification & Reference
* for information about standard algorithm names.
* @return the new Signature object.
* @throws NoSuchAlgorithmException if the algorithm is not available in the
* environment.
*/
public static Signature getInstance(String algorithm)
throws NoSuchAlgorithmException
{
Provider[] p = Security.getProviders();
for (int i = 0; i < p.length; i++)
{
try
{
return getInstance(algorithm, p[i]);
}
catch (NoSuchAlgorithmException ignored) {}
}
throw new NoSuchAlgorithmException(algorithm);
}
/**
* Generates a Signature
object implementing the specified
* algorithm, as supplied from the specified provider, if such an algorithm
* is available from the provider.
*
* @param algorithm the name of the algorithm requested. See Appendix A in
* the Java Cryptography Architecture API Specification & Reference for
* information about standard algorithm names.
* @param provider the name of the provider.
* @return the new Signature
object.
* @throws NoSuchAlgorithmException if the algorithm is not available in the
* package supplied by the requested provider.
* @throws NoSuchProviderException if the provider is not available in the
* environment.
* @throws IllegalArgumentException if the provider name is null
* or empty.
* @see Provider
*/
public static Signature getInstance(String algorithm, String provider)
throws NoSuchAlgorithmException, NoSuchProviderException
{
if (provider == null || provider.length() == 0)
throw new IllegalArgumentException("Illegal provider");
Provider p = Security.getProvider(provider);
if (p == null)
throw new NoSuchProviderException(provider);
return getInstance(algorithm, p);
}
/**
* Generates a Signature
object implementing the specified
* algorithm, as supplied from the specified provider, if such an algorithm
* is available from the provider. Note: the provider doesn't have to be
* registered.
*
* @param algorithm the name of the algorithm requested. See Appendix A in
* the Java Cryptography Architecture API Specification & Reference for
* information about standard algorithm names.
* @param provider the provider.
* @return the new Signature
object.
* @throws NoSuchAlgorithmException if the algorithm
is not
* available in the package supplied by the requested provider
.
* @throws IllegalArgumentException if the provider
is
* null
.
* @since 1.4
* @see Provider
*/
public static Signature getInstance(String algorithm, Provider provider)
throws NoSuchAlgorithmException
{
if (provider == null)
throw new IllegalArgumentException("Illegal provider");
Signature result = null;
Object o = null;
try
{
o = Engine.getInstance(SIGNATURE, algorithm, provider);
}
catch (java.lang.reflect.InvocationTargetException ite)
{
throw new NoSuchAlgorithmException(algorithm);
}
if (o instanceof SignatureSpi)
{
result = new DummySignature((SignatureSpi) o, algorithm);
}
else if (o instanceof Signature)
{
result = (Signature) o;
result.algorithm = algorithm;
}
else
{
throw new NoSuchAlgorithmException(algorithm);
}
result.provider = provider;
return result;
}
/**
* Returns the provider of this signature object.
*
* @return the provider of this signature object.
*/
public final Provider getProvider()
{
return provider;
}
/**
* Initializes this object for verification. If this method is called again
* with a different argument, it negates the effect of this call.
*
* @param publicKey the public key of the identity whose signature is going
* to be verified.
* @throws InvalidKeyException if the key is invalid.
*/
public final void initVerify(PublicKey publicKey) throws InvalidKeyException
{
state = VERIFY;
engineInitVerify(publicKey);
}
/**
* initSign(PrivateKey)
. That is, the object is reset and
* available to generate another signature from the same signer, if desired,
* via new calls to update()
and sign()
.outbuf
, starting at offset
*
. The format of the signature depends on the underlying signature
* scheme.initSign()
methods) and can be
* reused to generate further signatures with the same private key.initVerify(PublicKey)
. That is, the object is reset and
* available to verify another signature from the identity whose public key
* was specified in the call to initVerify()
.true
if the signature was verified, false
* if not.
* @throws SignatureException if this signature object is not initialized
* properly, or the passed-in signature is improperly encoded or of the wrong
* type, etc.
*/
public final boolean verify(byte[]signature) throws SignatureException
{
if (state == VERIFY)
{
state = UNINITIALIZED;
return engineVerify(signature);
}
else
throw new SignatureException();
}
/**
* signature
in the specified array of
* bytes, starting at the specified offset
.initVerify(PublicKey)
. That is, the object is reset and
* available to verify another signature from the identity whose public key
* was specified in the call to initVerify()
.true
if the signature was verified, false
* if not.
* @throws SignatureException if this signature object is not initialized
* properly, or the passed-in signature
is improperly encoded or
* of the wrong type, etc.
* @throws IllegalArgumentException if the signature
byte array
* is null
, or the offset
or length
is
* less than 0
, or the sum of the offset
and
* length
is greater than the length of the signature
* byte array.
*/
public final boolean verify(byte[] signature, int offset, int length)
throws SignatureException
{
if (state != VERIFY)
throw new SignatureException("illegal state");
if (signature == null)
throw new IllegalArgumentException("signaure is null");
if (offset < 0)
throw new IllegalArgumentException("offset is less than 0");
if (length < 0)
throw new IllegalArgumentException("length is less than 0");
if (offset + length < signature.length)
throw new IllegalArgumentException("range is out of bounds");
state = UNINITIALIZED;
return engineVerify(signature, offset, length);
}
/**
* Updates the data to be signed or verified by a byte.
*
* @param b the byte to use for the update.
* @throws SignatureException if this signature object is not initialized
* properly.
*/
public final void update(byte b) throws SignatureException
{
if (state != UNINITIALIZED)
engineUpdate(b);
else
throw new SignatureException();
}
/**
* Updates the data to be signed or verified, using the specified array of
* bytes.
*
* @param data the byte array to use for the update.
* @throws SignatureException if this signature object is not initialized
* properly.
*/
public final void update(byte[]data) throws SignatureException
{
if (state != UNINITIALIZED)
engineUpdate(data, 0, data.length);
else
throw new SignatureException();
}
/**
* Updates the data to be signed or verified, using the specified array of
* bytes, starting at the specified offset.
*
* @param data 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.
* @throws SignatureException if this signature object is not initialized
* properly.
*/
public final void update(byte[]data, int off, int len)
throws SignatureException
{
if (state != UNINITIALIZED)
engineUpdate(data, off, len);
else
throw new SignatureException();
}
/**
* Returns the name of the algorithm for this signature object.
*
* @return the name of the algorithm for this signature object.
*/
public final String getAlgorithm()
{
return algorithm;
}
/**
* Returns a string representation of this signature object, providing
* information that includes the state of the object and the name of the
* algorithm used.
*
* @return a string representation of this signature object.
*/
public String toString()
{
return (algorithm + " Signature");
}
/**
* 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.
* @throws InvalidParameterException if 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.
* @see #getParameter(String)
* @deprecated Use setParameter(AlgorithmParameterSpec).
*/
public final void setParameter(String param, Object value)
throws InvalidParameterException
{
engineSetParameter(param, value);
}
/**
* Initializes this signature engine with the specified parameter set.
*
* @param params the parameters.
* @throws InvalidAlgorithmParameterException if the given parameters are
* inappropriate for this signature engine.
* @see #getParameters()
*/
public final void setParameter(AlgorithmParameterSpec params)
throws InvalidAlgorithmParameterException
{
engineSetParameter(params);
}
/**
* null
if
* this signature does not use any parameters.
* @see #setParameter(AlgorithmParameterSpec)
*/
public final AlgorithmParameters getParameters()
{
return engineGetParameters();
}
/**
* 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.
* @throws InvalidParameterException if param is an invalid parameter for this
* engine, or another exception occurs while trying to get this parameter.
* @see #setParameter(String, Object)
* @deprecated
*/
public final Object getParameter(String param)
throws InvalidParameterException
{
return engineGetParameter(param);
}
/**
* Returns a clone if the implementation is cloneable.
*
* @return a clone if the implementation is cloneable.
* @throws CloneNotSupportedException if this is called on an implementation
* that does not support {@link Cloneable}.
*/
public Object clone() throws CloneNotSupportedException
{
throw new CloneNotSupportedException();
}
}