DOS/V Power Report 1998 February/VPR9802A.ISO/APP_DEMO/VC/MAIN.BIN/Security.java

Text File | 1997-10-27 | 15KB | 546 lines

/*
 * @(#)Security.java    1.54 97/02/06
 *
 * Copyright (c) 1995, 1996 Sun Microsystems, Inc. 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.
 *
 * SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF THE
 * SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR ANY DAMAGES
 * SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING
 * THIS SOFTWARE OR ITS DERIVATIVES.
 *
 * CopyrightVersion 1.1_beta
 *
 */

package java.security;

import java.util.*;
import java.io.*;
/**
 * <p>This class centralizes all security properties and common security
 * methods. One of its primary uses is to manage providers.
 *
 * @version 1.54 97/02/06
 * @author Benjamin Renaud */
public final class Security {

    /* Are we debugging? -- for developers */
    static boolean debug = false;

    /* Are we displaying errors? -- for users */
    static boolean error = true;

    /* The java.security properties */
    private static Properties props;

    /* Where we cache provider properties */
    private static Properties propCache;

    /* A vector of providers, in order of priority */
    private static Vector providers;

    static {
    initialize();
    }

    private static void initialize() {
    props = new Properties();
    propCache = new Properties();
    providers = new Vector();

    File propFile = securityPropFile("java.security");
    if (!propFile.exists()) {
        System.err.println("security properties not found. using defaults.");
        initializeStatic();
    } else {
        try {
        FileInputStream fis = new FileInputStream(propFile);
        props.load(fis);
        } catch (IOException e) {
        error("could not load security properties file from " + propFile +
              ". using defaults.");
        initializeStatic();
        }
    }
    loadProviders();
    }

    /*
     * Initialize to default values, if <java.home>/lib/java.security
     * is not found.
     */
    private static void initializeStatic() {
    props.put("security.provider.1", "sun.security.provider.Sun");
    props.put("system.scope","sun.security.provider.IdentityDatabase");
    }

    /**
     * Don't let anyone instantiate this.
     */
    private Security() {
    }

    /**
     * Loops through provider declarations, which are expected to be
     * of the form:
     *
     * security.provider.1=sun.security.provider.Sun
     * security.provider.2=sun.security.jsafe.Jsafe
     * etc.
     *
     * The order determines the default search order when looking for
     * an algorithm.
     */
    private static void loadProviders() {

    int i = 1;

    while(true) {

        String name = props.getProperty("security.provider." + i++);
        if (name == null) {
        break;

        } else {
        Provider prov = Provider.loadProvider(name);
        if (prov != null) {
            /* This must manipulate the datastructure
               directly, because going through addProviders
               causes a security check to happen, which
               sometimes will cause the security
               initialization to fail with bad
               consequences. */
            providers.addElement(prov);
        }
        }
    }
    }

    static File securityPropFile(String filename) {
    // maybe check for a system property which will specify where to
    // look. Someday.
    String sep = File.separator;
    return new File(System.getProperty("java.home") + sep + "lib" + sep +
            "security" + sep + filename);
    }

    /**
     * Looks up providers, and returns the property mapping the key,
     * if any. The order in which the providers are looked up is the
     * provider-preference order, as specificed in the security
     * properties file.
     */
    static String getProviderProperty(String key) {

    String prop = propCache.getProperty(key);
    if (prop != null) {
        return prop;
    }

    for (int i = 0; i < providers.size(); i++) {
        Provider prov = (Provider)providers.elementAt(i);

        prop = prov.getProperty(key);
        if (prop != null) {
        propCache.put(key, prop);
        return prop;
        }
    }
    return prop;
    }

    /**
     * We always map names to standard names
     */
    static String getStandardName(String alias, String engineType) {
    return getProviderProperty("Alg.Alias." + engineType + "." + alias);
    }

    /**
     * Gets a specified property for an algorithm. The algorithm name
     * should be a standard name. 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.
     * One possible use is by specialized algorithm parsers, which may map
     * classes to algorithms which they understand (much like Key parsers
     * do).
     *
     * @param algName the algorithm name.
     *
     * @param propName the name of the property to get.
     *
     * @return the value of the specified property.
     */
    public static String getAlgorithmProperty(String algName,
                          String propName) {
    return getProviderProperty("Alg." + propName + "." + algName);
    }

    /**
     * Given an algorithm name, returns the name of PublicKey class
     * capable of handling keys for that algorithm. The algorithm name
     * should be a standard name. 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 algName the standard algorithm name for which to get
     * a public key class name.
     */
    static String getPublicKeyClassName(String algName, String format) {

    String stdName = getStandardName(algName, "Key");

    if (stdName == null) {
        stdName = algName;
    }

    String formatAndAlg = "PublicKey." + format + "." + stdName;
    return getProviderProperty(formatAndAlg);
    }


    /** Given an algorithm name, returns the name of PrivateKey class
     * capable of handling keys for that algorithm. The algorithm name
     * should be a standard name. 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.
     */
    static String getPrivateKeyClassName(String algName, String format) {

    String stdName = getStandardName(algName, "Key");

    if (stdName == null) {
        stdName = algName;
    }

    return getProviderProperty("PrivateKey." + format + "." + stdName);
    }

    static String getEngineClassName(String algName,
                     String engineType)
    throws NoSuchAlgorithmException {
    /* First get the standard name */
    String stdName = getStandardName(algName, engineType);

    if (stdName == null) {
        stdName = algName;
    }

    Class impl = null;

    Enumeration enum = providers.elements();

    String classname = getProviderProperty(engineType + "." + stdName);

    if (classname != null) {
        return classname;
    }

    throw new NoSuchAlgorithmException("algorithm " + algName +
                       " not available.");
    }

    /** Given an algorithm name, returns the name of Signature class
     * capable of handling keys for that algorithm. The algorithm name
     * should be a standard name. 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.
     */
    private static String getEngineClassName(String algName, String provider,
                         String engineType)
    throws NoSuchAlgorithmException, NoSuchProviderException {

    if (provider == null) {
        return getEngineClassName(algName, engineType);
    }

    /* First get the standard name */
    String stdName = getStandardName(algName, engineType);

    if (stdName == null) {
        stdName = algName;
    }

    Provider prov = getProvider(provider);
    if (prov == null) {
        throw new NoSuchProviderException("no such provider: " +
                        provider);
    }

    String className = prov.getProperty(engineType + "." + stdName);
    if (className == null) {
        throw new NoSuchAlgorithmException("no such algorithm: " +
                             algName +
                             " for provider " +
                         provider);
    }
    return className;
    }

    /**
     * Adds a new provider, at a specified position. The position is
     * the preference order in which providers are searched for
     * requested algorithms. Note that it is not guaranteed that this
     * preference will be respected. The position is 1-based, that is,
     * 1 is most preferred, followed by 2, and so on. Sometimes it
     * will be legal to add a provider, but only in the last position,
     * in which case the <code>position</code> argument will be ignored.
     *
     * <p>A provider cannot be added if it is already installed.
     *
     * @param provider the provider to be added.
     *
     * @param position the preference position that the caller would
     * like for this provider.
     *
     * @return the actual preference position in which the provider was
     * added, or -1 if the provider was not added because it is
     * already installed.
     *
     * @see #getProvider
     * @see #removeProvider
     */
    public static int insertProviderAt(Provider provider, int position) {

    check();

    /* First check if the provider is already installed */
    Provider already = getProvider(provider.getName());
    if (already != null) {
        return -1;
    }

    /* Internally, position is position - 1 */
    position--;

    if (position < 0) {
        position = 0;
    }

    int size = providers.size();
    if (position > size) {
        position = size;
    }

    providers.insertElementAt(provider, position);

    /* clear the prop caches */
    propCache = new Properties();

    return position;
    }

    /**
     * Adds a provider to the next position available.
     *
     * @param provider the provider to be added.
     *
     * @return the preference position in which the provider was
     * added, or -1 if the provider was not added because it is
     * already installed.
     *
     * @see #getProvider
     * @see #removeProvider
     */
    public static int addProvider(Provider provider) {

    return insertProviderAt(provider, providers.size() + 1);
    }

    /**
     * Removes the provider with the specified name.  This method
     * returns silently if the provider is not installed.
     *
     * @param name the name of the provider to remove.
     *
     * @see #getProvider
     * @see #addProvider
     */
    public static void removeProvider(String name) {

    check();

    Provider provider = getProvider(name);

    if (provider != null) {
        providers.removeElement(provider);
    }
    }


    /**
     * Returns all providers currently installed.
     *
     * @return an array of all providers currently installed.
     */
    public static Provider[] getProviders() {
    check();
    Provider[] result = new Provider[providers.size()];
    providers.copyInto(result);
    return result;
    }

    /**
     * Returns the provider installed with the specified name, if
     * any. Returns null if no provider with the speicified name is
     * installed.
     *
     * @param name the name of the provider to get.
     *
     * @return the provider of the specified name.
     *
     * @see #removeProvider
     * @see #addProvider
     */
    public static Provider getProvider(String name) {
    check();
    Enumeration enum = providers.elements();
    while (enum.hasMoreElements()) {
        Provider prov = (Provider)enum.nextElement();
        if (prov.getName().equals(name)) {
        return prov;
        }
    }
    return null;
    }

    private static boolean checkSuperclass(Class subclass, Class superclass) {
    while(!subclass.equals(superclass)) {
        subclass = subclass.getSuperclass();
        if (subclass == null) {
        return false;
        }
    }
    return true;
    }

    /*
     * Return an object configured to implemented type. Provider can
     * be null, in which case all providers will be searched in order
     * of preference.
     */
    static Object getImpl(String algorithm, String type, String provider)
    throws NoSuchAlgorithmException, NoSuchProviderException {

    String className = getEngineClassName(algorithm, provider, type);

    try {
        Class typeClass = Class.forName("java.security." + type);
        Class cl = Class.forName(className);

        if (checkSuperclass(cl, typeClass)) {
        return cl.newInstance();
        } else {
        throw new NoSuchAlgorithmException("class configured for " +
                           type + ": " + className +
                           " not a " + type);
        }
    } catch (ClassNotFoundException e) {
        throw new NoSuchAlgorithmException("class configured for " +
                           type + "(provider: " +
                           provider + ")" +
                           "cannot be found.\n" +
                           e.getMessage());
    } catch (InstantiationException e) {
        throw new NoSuchAlgorithmException("class " + className +
                           " configured for " + type +
                           "(provider: " + provider +
                           ") cannot be instantiated.\n" +
                           e.getMessage());
    } catch (IllegalAccessException e) {
        throw new NoSuchAlgorithmException("class " + className +
                           " configured for " + type +
                           "(provider: " + provider +
                           ") cannot be accessed.\n" +
                           e.getMessage());
    }
    }

    /**
     * Gets a security property.
     *
     * @param key the key of the property being retrieved.
     *
     * @return the valeu of the security property corresponding to key.
     */
    public static String getProperty(String key) {
    check();
    return props.getProperty(key);
    }

    /**
     * Sets a security property.
     *
     * @param key the name of the property to be set.
     *
     * @param datum the value of the property to be set.
     */
    public static void setProperty(String key, String datum) {
    check();
    props.put(key, datum);
    }

    private static void check() {

    SecurityManager security = System.getSecurityManager();
    if (security != null) {
        security.checkSecurityAccess("java");
    }
    }

    /**
     * Print an error message that may be significant to a user.
     */
    static void error(String msg) {
    if (debug) {
        System.err.println(msg);
    }
    }

    /**
     * Print an error message that may be significant to a user.
     */
    static void error(String msg, Throwable t) {
    error(msg);
    if (debug) {
        t.printStackTrace();
    }
    }

    /**
     * Print an debugging message that may be significant to a developer.
     */
    static void debug(String msg) {
    if (debug) {
        System.err.println(msg);
    }
    }

    /**
     * Print an debugging message that may be significant to a developer.
     */
    static void debug(String msg, Throwable t) {
    if (debug) {
        t.printStackTrace();
        System.err.println(msg);
    }
    }



}