Java 1.2 How-To/JavaHowTo.iso/3rdParty/jbuilder/unsupported/JDK1.2beta3/SOURCE/SRC.ZIP/java/security/Signature.java

Java Source | 1998-03-20 | 20.3 KB | 617 lines

/*
 * @(#)Signature.java    1.66 98/03/18
 *
 * Copyright 1996-1998 by Sun Microsystems, Inc.,
 * 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
 * All rights reserved.
 *
 * This software is the confidential and proprietary information
 * of Sun Microsystems, Inc. ("Confidential Information").  You
 * shall not disclose such Confidential Information and shall use
 * it only in accordance with the terms of the license agreement
 * you entered into with Sun.
 */

package java.security;

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

/**
 * 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.
 *
 * <p> The signature algorithm can be, among others, the NIST standard
 * DSA, using DSA and SHA-1. The DSA algorithm using the
 * SHA-1 message digest algorithm can be specified, for example, as
 * <tt>SHA/DSA</tt> or <tt>SHA-1/DSA</tt> (they are equivalent).
 * In the case of RSA, there are multiple choices for the message digest
 * algorithm, so the signing algorithm could be specified as, for example,
 * <tt>MD2/RSA</tt>, <tt>MD5/RSA</tt>, or <tt>SHA-1/RSA</tt>.
 * The algorithm name must be specified, as there is no default.
 *
 * <p>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 <code>getInstance </code> methods.
 *
 * <p>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. <ul>
 *
 * <li>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.<p>
 *
 * <li>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.
 *
 * </ul>
 *
 * <p>A Signature object can be used to generate and verify digital
 * signatures.
 *
 * <p>There are three phases to the use of a Signature object for
 * either signing data or verifying a signature:<ol>
 *
 * <li>Initialization, with either
 *
 *     <ul>
 *
 *     <li>a public key, which initializes the signature for
 *     verification (see <a href = "#initVerify">initVerify</a>), or
 *
 *     <li>a private key (and optionally a Secure Random Number Generator),
 *     which initializes the signature for signing
 *     (see <a href = "#initSign">initSign</a>).
 *
 *     </ul><p>
 *
 * <li>Updating<p>
 *
 * <p>Depending on the type of initialization, this will update the
 * bytes to be signed or verified. See the <a href =
 * "#update(byte)">update</a> methods.<p>
 *
 * <li>Signing or Verifying a signature on all updated bytes. See <a
 * href = "#sign">sign</a> and <a href = "#verify">verify</a>.
 *
 * </ol>
 *
 * <p>Note that this class is abstract and extends from
 * <code>SignatureSpi</code> for historical reasons.
 * Application developers should only take notice of the methods defined in
 * this <code>Signature</code> class, and ignore all the methods in
 * the superclass.
 *
 * @author Benjamin Renaud
 *
 * @version 1.66 98/03/18
 */

public abstract class Signature extends SignatureSpi {

    /*  Are we in debugging mode? */
    private static final boolean debug = false;

    /*
     * The algorithm for this signature object.
     * This value is used to map an OID to the particular algorithm.
     * The mapping is done in AlgorithmObject.algOID(String algorithm)
     */
    private String algorithm;

    // The provider
    private Provider provider;

    /**
     * Possible <a href = "#state ">state </a> value, signifying that
     * this signature object has not yet been initialized.
     */
    protected final static int UNINITIALIZED = 0;

    /**
     * Possible <a href = "#state ">state </a> value, signifying that
     * this signature object has been initialized for signing.
     */
    protected final static int SIGN = 2;

    /**
     * Possible <a href = "#state ">state </a> value, signifying that
     * this signature object has been initialized for verification.
     */
    protected final static int VERIFY = 3;

    /**
     * Current state of this signature object.
     */
    protected int state = UNINITIALIZED;

    /**
     * Creates a Signature object for the specified algorithm.
     *
     * @param algorithm the standard string name of the algorithm.
     * See Appendix A in the <a href=
     * "../guide/security/CryptoSpec.html#AppA">
     * Java Cryptography Architecture API Specification & Reference </a>
     * for information about standard algorithm names.
     */
    protected Signature(String algorithm) {
    this.algorithm = algorithm;
    }

    /**
     * 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 <a href=
     * "../guide/security/CryptoSpec.html#AppA">
     * Java Cryptography Architecture API Specification & Reference </a>
     * for information about standard algorithm names.
     *
     * @return the new Signature object.
     *
     * @exception NoSuchAlgorithmException if the algorithm is
     * not available in the environment.
     */
    public static Signature getInstance(String algorithm)
    throws NoSuchAlgorithmException {
    if (algorithm.equalsIgnoreCase("DSA"))
        algorithm = new String("SHA/DSA");
    try {
        Object[] objs = Security.getImpl(algorithm, "Signature", null);
        if (objs[0] instanceof Signature) {
        Signature sig = (Signature)objs[0];
        sig.provider = (Provider)objs[1];
        return sig;
        } else {
        Delegate delegate = new Delegate((SignatureSpi)objs[0],
                         algorithm);
        delegate.provider = (Provider)objs[1];
        return delegate;
        }
    } catch(NoSuchProviderException e) {
        throw new NoSuchAlgorithmException(algorithm + " not found");
    }
    }

    /**
     * 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 <a href=
     * "../guide/security/CryptoSpec.html#AppA">
     * Java Cryptography Architecture API Specification & Reference </a>
     * for information about standard algorithm names.
     *
     * @param provider the name of the provider.
     *
     * @return the new Signature object.
     *
     * @exception NoSuchAlgorithmException if the algorithm is
     * not available in the package supplied by the requested
     * provider.
     *
     * @exception NoSuchProviderException if the provider is not
     * available in the environment.
     *
     * @see Provider
     */
    public static Signature getInstance(String algorithm, String provider)
    throws NoSuchAlgorithmException, NoSuchProviderException {
    if (algorithm.equalsIgnoreCase("DSA"))
        algorithm = new String("SHA/DSA");
    Object[] objs = Security.getImpl(algorithm, "Signature", provider);
    if (objs[0] instanceof Signature) {
        Signature sig = (Signature)objs[0];
        sig.provider = (Provider)objs[1];
        return sig;
    } else {
        Delegate delegate = new Delegate((SignatureSpi)objs[0], algorithm);
        delegate.provider = (Provider)objs[1];
        return delegate;
    }
    }

    /**
     * Returns the provider of this signature object.
     *
     * @return the provider of this signature object
     */
    public final Provider getProvider() {
    return this.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.
     *
     * @exception InvalidKeyException if the key is invalid.
     */
    public final void initVerify(PublicKey publicKey)
    throws InvalidKeyException {
        engineInitVerify(publicKey);
        state = VERIFY;
    }

    /**
     * Initialize this object for signing. If this method is called
     * again with a different argument, it negates the effect
     * of this call.
     *
     * @param privateKey the private key of the identity whose signature
     * is going to be generated.
     *
     * @exception InvalidKeyException if the key is invalid.
     */
    public final void initSign(PrivateKey privateKey)
    throws InvalidKeyException {
        engineInitSign(privateKey);
        state = SIGN;
    }

    /**
     * Initialize this object for signing. If this method is called
     * again with a different argument, it negates the effect
     * of this call.
     *
     * @param privateKey the private key of the identity whose signature
     * is going to be generated.
     *
     * @param random the source of randomness for this signature.
     *
     * @exception InvalidKeyException if the key is invalid.
     */
    public final void initSign(PrivateKey privateKey, SecureRandom random)
    throws InvalidKeyException {
        engineInitSign(privateKey, random);
        state = SIGN;
    }

    /**
     * Returns the signature bytes of all the data updated.  The
     * signature returned is X.509-encoded.
     *
     * <p>A call to this method resets this signature object to the state
     * it was in when previously initialized for signing via a
     * call to <code>initSign(PrivateKey)</code>. That is, the object is
     * reset and available to generate another signature from the same
     * signer, if desired, via new calls to <code>update</code> and
     * <code>sign</code>.
     *
     * @return the signature bytes of the signing operation's result.
     *
     * @exception SignatureException if this signature object is not
     * initialized properly.
     */
    public final byte[] sign() throws SignatureException {
    if (state == SIGN) {
        return engineSign();
    }
    throw new SignatureException("object not initialized for " +
                     "signing");
    }

    /**
     * Verifies the passed-in signature. The signature bytes are expected
     * to be X.509-encoded.
     *
     * <p>A call to this method resets this signature object to the state
     * it was in when previously initialized for verification via a
     * call to <code>initVerify(PublicKey)</code>. That is, the object is
     * reset and available to verify another signature from the identity
     * whose public key was specified in the call to <code>initVerify</code>.
     *
     * @param signature the signature bytes to be verified.
     *
     * @return true if the signature was verified, false if not.
     *
     * @exception 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) {
        return engineVerify(signature);
    }
    throw new SignatureException("object not initialized for " +
                     "verification");
    }

    /**
     * Updates the data to be signed or verified by a byte.
     *
     * @param b the byte to use for the update.
     *
     * @exception SignatureException if this signature object is not
     * initialized properly.
     */
    public final void update(byte b) throws SignatureException {
    if (state == VERIFY || state == SIGN) {
        engineUpdate(b);
    } else {
        throw new SignatureException("object not initialized for "
                     + "signature or verification");
    }
    }

    /**
     * Updates the data to be signed or verified, using the specified
     * array of bytes.
     *
     * @param data the byte array to use for the update.
     *
     * @exception SignatureException if this signature object is not
     * initialized properly.
     */
    public final void update(byte[] data) throws SignatureException {
    update(data, 0, data.length);
    }

    /**
     * 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.
     *
     * @exception SignatureException if this signature object is not
     * initialized properly.
     */
    public final void update(byte[] data, int off, int len)
    throws SignatureException {
        if (state == SIGN || state == VERIFY) {
        engineUpdate(data, off, len);
        } else {
        throw new SignatureException("object not initialized for "
                         + "signature or verification");
        }
    }

    /**
     * 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 this.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() {
    String initState = "";
    switch (state) {
    case UNINITIALIZED:
        initState = "<not initialized>";
        break;
      case VERIFY:
        initState = "<initialized for verifying>";
        break;
      case SIGN:
        initState = "<initialized for signing>";
        break;
    }
    return "Signature object: " + getAlgorithm() + initState;
    }

    /**
     * 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 Use <a href = "#setParameter(AlgorithmParameterSpec)">
     * setParameter</a>.
     */
    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
     *
     * @exception InvalidAlgorithmParameterException if the given parameters
     * are inappropriate for this signature engine
     */
    public final void setParameter(AlgorithmParameterSpec params)
    throws InvalidAlgorithmParameterException {
        engineSetParameter(params);
    }

    /**
     * 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
     */
    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.
     *
     * @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();
    }
    }

    // private debugging method.
    private static void debug(String statement) {
    if (debug) {
        System.err.println(statement);
    }
    }

    // private debugging method.
    private static void debug(Exception e) {
    if (debug) {
        e.printStackTrace();
    }
    }




    /*
     * The following class allows providers to extend from SignatureSpi
     * rather than from Signature. It represents a Signature with an
     * encapsulated, provider-supplied SPI object (of type SignatureSpi).
     * If the provider implementation is an instance of SignatureSpi, the
     * getInstance() methods above return an instance of this class, with
     * the SPI object encapsulated.
     *
     * Note: All SPI methods from the original Signature class have been
     * moved up the hierarchy into a new class (SignatureSpi), which has
     * been interposed in the hierarchy between the API (Signature)
     * and its original parent (Object).
     */

    static class Delegate extends Signature {

    // The provider implementation (delegate)
    private SignatureSpi sigSpi;

    // constructor
    public Delegate(SignatureSpi sigSpi, String algorithm) {
        super(algorithm);
        this.sigSpi = sigSpi;
    }

    /*
     * Returns a clone if the delegate is cloneable.
     *
     * @return a clone if the delegate is cloneable.
     *
     * @exception CloneNotSupportedException if this is called on a
     * delegate that does not support <code>Cloneable</code>.
     */
    public Object clone() throws CloneNotSupportedException {
        if (sigSpi instanceof Cloneable) {
        SignatureSpi sigSpiClone = (SignatureSpi)sigSpi.clone();
        Delegate that = new Delegate(sigSpiClone, algorithm);
        that.provider = provider;
        return that;
        } else {
        throw new CloneNotSupportedException();
        }
    }

    protected void engineInitVerify(PublicKey publicKey)
        throws InvalidKeyException {
        sigSpi.engineInitVerify(publicKey);
    }

    protected void engineInitSign(PrivateKey privateKey)
        throws InvalidKeyException {
        sigSpi.engineInitSign(privateKey);
    }

    protected void engineUpdate(byte b) throws SignatureException {
        sigSpi.engineUpdate(b);
    }

    protected void engineUpdate(byte[] b, int off, int len)
        throws SignatureException {
        sigSpi.engineUpdate(b, off, len);
    }

    protected byte[] engineSign() throws SignatureException {
        return sigSpi.engineSign();
    }

    protected boolean engineVerify(byte[] sigBytes)
        throws SignatureException {
        return sigSpi.engineVerify(sigBytes);
    }

    protected void engineSetParameter(String param, Object value)
        throws InvalidParameterException {
        sigSpi.engineSetParameter(param, value);
    }

    protected void engineSetParameter(AlgorithmParameterSpec params)
        throws InvalidAlgorithmParameterException {
        sigSpi.engineSetParameter(params);
    }

    protected Object engineGetParameter(String param)
        throws InvalidParameterException {
        return sigSpi.engineGetParameter(param);
    }
    }
}