Authentication and Security

public interface Realm {
    // Container
    Container getContainer();
    void setContainer(Container container);
    
    // Credential handler
    CredentialHandler getCredentialHandler();
    void setCredentialHandler(CredentialHandler credentialHandler);
    
    // Authentication methods
    Principal authenticate(String username);
    Principal authenticate(String username, String credentials);
    Principal authenticate(String username, String digest, String nonce, String nc,
        String cnonce, String qop, String realm, String digestA2);
    Principal authenticate(String username, String digest, String nonce, String nc,
        String cnonce, String qop, String realm, String digestA2, String algorithm);
    Principal authenticate(GSSContext gssContext, boolean storeCreds);
    Principal authenticate(GSSName gssName, GSSCredential gssCredential);
    Principal authenticate(X509Certificate[] certs);
    
    // Authorization
    boolean hasRole(Wrapper wrapper, Principal principal, String role);
    boolean hasResourcePermission(Request request, Response response, 
        SecurityConstraint[] constraints, Context context) throws IOException;
    boolean hasUserDataPermission(Request request, Response response, 
        SecurityConstraint[] constraints) throws IOException;
    
    // Background processing
    void backgroundProcess();
    
    // Security constraints
    SecurityConstraint[] findSecurityConstraints(Request request, Context context);
    
    // Event listeners
    void addPropertyChangeListener(PropertyChangeListener listener);
    void removePropertyChangeListener(PropertyChangeListener listener);
}

/**
 * Base class for Realm implementations providing common functionality.
 */
public abstract class RealmBase implements Realm, Lifecycle {
    protected Container container;
    protected CredentialHandler credentialHandler;

    // Subclasses must implement these methods
    protected abstract String getPassword(String username);
    protected abstract Principal getPrincipal(String username);
    public abstract boolean hasRole(Wrapper wrapper, Principal principal, String role);
}

/**
 * Simple in-memory realm for development and testing.
 * Users and roles are defined in tomcat-users.xml.
 */
public class MemoryRealm extends RealmBase {
    public MemoryRealm();

    /** Set path to the users configuration file */
    public void setPathname(String pathname);
    public String getPathname();
}

/**
 * Realm implementation that reads user information from a JDBC database.
 */
public class DataSourceRealm extends RealmBase {
    public DataSourceRealm();

    /** Set the JNDI name of the DataSource */
    public void setDataSourceName(String dataSourceName);
    public String getDataSourceName();

    /** Set the SQL query to retrieve user credentials */
    public void setUserCredCol(String userCredCol);
    public String getUserCredCol();

    /** Set the SQL query to retrieve user roles */
    public void setUserRoleTable(String userRoleTable);
    public String getUserRoleTable();

    /** Set the name column in user table */
    public void setUserNameCol(String userNameCol);
    public String getUserNameCol();

    /** Set the name of the user table */
    public void setUserTable(String userTable);
    public String getUserTable();

    /** Set the role name column */
    public void setRoleNameCol(String roleNameCol);
    public String getRoleNameCol();
}

/**
 * Realm implementation that authenticates users against an LDAP directory.
 */
public class JNDIRealm extends RealmBase {
    public JNDIRealm();

    /** Set the connection URL for the LDAP server */
    public void setConnectionURL(String connectionURL);
    public String getConnectionURL();

    /** Set the connection name (DN) to use for authentication */
    public void setConnectionName(String connectionName);
    public String getConnectionName();

    /** Set the connection password */
    public void setConnectionPassword(String connectionPassword);

    /** Set the base DN for user searches */
    public void setUserBase(String userBase);
    public String getUserBase();

    /** Set the search pattern for finding users */
    public void setUserSearch(String userSearch);
    public String getUserSearch();

    /** Set the base DN for role searches */
    public void setRoleBase(String roleBase);
    public String getRoleBase();

    /** Set the search pattern for finding roles */
    public void setRoleSearch(String roleSearch);
    public String getRoleSearch();

    /** Set the attribute name for role names */
    public void setRoleName(String roleName);
    public String getRoleName();

    /** Set whether to use subtree scope for searches */
    public void setRoleSubtree(boolean roleSubtree);
    public boolean getRoleSubtree();

    /** Set whether nested groups should be searched */
    public void setRoleNested(boolean roleNested);
    public boolean getRoleNested();
}

/**
 * Realm implementation that uses JAAS for authentication.
 */
public class JAASRealm extends RealmBase {
    public JAASRealm();

    /** Set the JAAS application name */
    public void setAppName(String appName);
    public String getAppName();

    /** Set the user class name */
    public void setUserClassNames(String userClassNames);
    public String getUserClassNames();

    /** Set the role class names */
    public void setRoleClassNames(String roleClassNames);
    public String getRoleClassNames();

    /** Set whether to use context class loader */
    public void setUseContextClassLoader(boolean useContextClassLoader);
    public boolean isUseContextClassLoader();
}

/**
 * Realm implementation that uses the UserDatabase JNDI resource.
 */
public class UserDatabaseRealm extends RealmBase {
    public UserDatabaseRealm();

    /** Set the JNDI name of the UserDatabase resource */
    public void setResourceName(String resourceName);
    public String getResourceName();
}

/**
 * Realm that combines multiple realms for authentication.
 * Attempts authentication against each realm in sequence.
 */
public class CombinedRealm extends RealmBase {
    public CombinedRealm();

    /** Add a realm to the combined realm */
    public void addRealm(Realm realm);

    /** Get all configured realms */
    public Realm[] getNestedRealms();
}

/**
 * Realm that provides brute force attack protection by locking out users
 * after too many failed authentication attempts.
 */
public class LockOutRealm extends CombinedRealm {
    public LockOutRealm();

    /** Set the number of failed attempts before lockout */
    public void setFailureCount(int failureCount);
    public int getFailureCount();

    /** Set the lockout duration in seconds */
    public void setLockOutTime(int lockOutTime);
    public int getLockOutTime();

    /** Set the time window for counting failures in seconds */
    public void setCacheSize(int cacheSize);
    public int getCacheSize();

    /** Set whether to cache authenticated users */
    public void setCacheRemovalWarningTime(int cacheRemovalWarningTime);
    public int getCacheRemovalWarningTime();
}

/**
 * No-op realm that always denies authentication.
 * Useful for applications that don't require authentication.
 */
public class NullRealm extends RealmBase {
    public NullRealm();
}

/**
 * Base credential handler interface.
 */
public interface CredentialHandler {
    boolean matches(String inputCredentials, String storedCredentials);
    String mutate(String inputCredentials);
}

/**
 * Credential handler using message digest algorithms (MD5, SHA-256, etc.).
 */
public class MessageDigestCredentialHandler implements CredentialHandler {
    public MessageDigestCredentialHandler();

    /** Set the digest algorithm (e.g., "SHA-256", "MD5") */
    public void setAlgorithm(String algorithm);
    public String getAlgorithm();

    /** Set the digest encoding ("hex" or "base64") */
    public void setEncoding(String encoding);
    public String getEncoding();

    /** Set the number of iterations for key derivation */
    public void setIterations(int iterations);
    public int getIterations();

    /** Set the salt length in bytes */
    public void setSaltLength(int saltLength);
    public int getSaltLength();

    @Override
    public boolean matches(String inputCredentials, String storedCredentials);

    @Override
    public String mutate(String inputCredentials);
}

/**
 * Credential handler using SecretKeyFactory for PBKDF2 and similar algorithms.
 */
public class SecretKeyCredentialHandler implements CredentialHandler {
    public SecretKeyCredentialHandler();

    /** Set the algorithm (e.g., "PBKDF2WithHmacSHA256") */
    public void setAlgorithm(String algorithm);
    public String getAlgorithm();

    /** Set the number of iterations */
    public void setIterations(int iterations);
    public int getIterations();

    /** Set the key length in bits */
    public void setKeyLength(int keyLength);
    public int getKeyLength();

    /** Set the salt length in bytes */
    public void setSaltLength(int saltLength);
    public int getSaltLength();

    @Override
    public boolean matches(String inputCredentials, String storedCredentials);

    @Override
    public String mutate(String inputCredentials);
}

/**
 * Credential handler that supports multiple nested credential handlers.
 * Tries each handler in sequence for matching.
 */
public class NestedCredentialHandler implements CredentialHandler {
    public NestedCredentialHandler();

    /** Add a credential handler */
    public void addCredentialHandler(CredentialHandler handler);

    /** Get all configured credential handlers */
    public CredentialHandler[] getCredentialHandlers();

    @Override
    public boolean matches(String inputCredentials, String storedCredentials);

    @Override
    public String mutate(String inputCredentials);
}

import org.apache.catalina.realm.DataSourceRealm;
import org.apache.catalina.realm.MessageDigestCredentialHandler;

// Configure DataSource realm with SHA-256 password hashing
DataSourceRealm realm = new DataSourceRealm();
realm.setDataSourceName("java:comp/env/jdbc/UserDB");
realm.setUserTable("users");
realm.setUserNameCol("username");
realm.setUserCredCol("password");
realm.setUserRoleTable("user_roles");
realm.setRoleNameCol("role_name");

// Configure credential handler
MessageDigestCredentialHandler credentialHandler = new MessageDigestCredentialHandler();
credentialHandler.setAlgorithm("SHA-256");
credentialHandler.setIterations(100000);
credentialHandler.setSaltLength(32);
realm.setCredentialHandler(credentialHandler);

// Attach to context
context.setRealm(realm);

public interface Authenticator {
    boolean authenticate(Request request, HttpServletResponse response) throws IOException;
    void login(String userName, String password, Request request) throws ServletException;
    void logout(Request request);
}

public class SecurityConstraint implements Serializable {
    // Constructor
    public SecurityConstraint();
    
    // Display name
    public void setDisplayName(String displayName);
    public String getDisplayName();
    
    // Auth constraint
    public void setAuthConstraint(boolean authConstraint);
    public boolean getAuthConstraint();
    public void addAuthRole(String authRole);
    public boolean findAuthRole(String role);
    public String[] findAuthRoles();
    public void removeAuthRole(String authRole);
    
    // User data constraint
    public void setUserConstraint(String userConstraint);
    public String getUserConstraint();
    
    // Collections
    public void addCollection(SecurityCollection collection);
    public SecurityCollection[] findCollections();
    public void removeCollection(SecurityCollection collection);
}

public class SecurityCollection implements Serializable {
    // Constructor
    public SecurityCollection();
    public SecurityCollection(String name);
    
    // Name and description
    public void setName(String name);
    public String getName();
    public void setDescription(String description);
    public String getDescription();
    
    // URL patterns
    public void addPattern(String pattern);
    public boolean findPattern(String pattern);
    public String[] findPatterns();
    public void removePattern(String pattern);
    
    // HTTP methods
    public void addMethod(String method);
    public boolean findMethod(String method);
    public String[] findMethods();
    public void removeMethod(String method);
    
    // Omitted HTTP methods
    public void addOmittedMethod(String method);
    public boolean findOmittedMethod(String method);
    public String[] findOmittedMethods();
    public void removeOmittedMethod(String method);
}

public class LoginConfig implements Serializable {
    // Constructor
    public LoginConfig();

    // Authentication method
    public void setAuthMethod(String authMethod);
    public String getAuthMethod();

    // Realm name
    public void setRealmName(String realmName);
    public String getRealmName();

    // Login and error pages (for FORM authentication)
    public void setLoginPage(String loginPage);
    public String getLoginPage();
    public void setErrorPage(String errorPage);
    public String getErrorPage();
}

// Server authentication module
public interface ServerAuthModule {
    void initialize(MessagePolicy requestPolicy, MessagePolicy responsePolicy, 
        CallbackHandler handler, Map<String,Object> options) throws AuthException;
    AuthStatus validateRequest(MessageInfo messageInfo, Subject clientSubject, 
        Subject serviceSubject) throws AuthException;
    AuthStatus secureResponse(MessageInfo messageInfo, Subject serviceSubject) 
        throws AuthException;
    void cleanSubject(MessageInfo messageInfo, Subject subject) throws AuthException;
    Class<?>[] getSupportedMessageTypes();
}

// Authentication status
public class AuthStatus {
    public static final AuthStatus SUCCESS;
    public static final AuthStatus FAILURE;
    public static final AuthStatus SEND_SUCCESS;
    public static final AuthStatus SEND_FAILURE;
    public static final AuthStatus SEND_CONTINUE;
}

// Message info
public interface MessageInfo {
    Object getRequestMessage();
    Object getResponseMessage();
    void setRequestMessage(Object request);
    void setResponseMessage(Object response);
    Map<String,Object> getMap();
}

import org.apache.catalina.startup.Tomcat;
import org.apache.catalina.Context;
import org.apache.tomcat.util.descriptor.web.SecurityConstraint;
import org.apache.tomcat.util.descriptor.web.SecurityCollection;
import org.apache.tomcat.util.descriptor.web.LoginConfig;

public class BasicAuthExample {
    public static void main(String[] args) throws Exception {
        Tomcat tomcat = new Tomcat();
        tomcat.setPort(8080);
        
        Context ctx = tomcat.addWebapp("/secure", "/path/to/webapp");
        
        // Add users
        tomcat.addUser("admin", "admin123");
        tomcat.addRole("admin", "manager");
        
        // Add security constraint
        SecurityConstraint constraint = new SecurityConstraint();
        constraint.setAuthConstraint(true);
        constraint.addAuthRole("manager");
        
        SecurityCollection collection = new SecurityCollection();
        collection.addPattern("/admin/*");
        constraint.addCollection(collection);
        
        ctx.addConstraint(constraint);
        
        // Configure login
        LoginConfig config = new LoginConfig();
        config.setAuthMethod("BASIC");
        config.setRealmName("Protected Area");
        ctx.setLoginConfig(config);
        
        tomcat.start();
        tomcat.getServer().await();
    }
}