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package java.security.cert;

import java.security.AccessController;
import java.security.InvalidAlgorithmParameterException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.PrivilegedAction;
import java.security.Provider;
import java.security.Security;
import java.util.Objects;

import sun.security.jca.*;
import sun.security.jca.GetInstance.Instance;

A class for building certification paths (also known as certificate chains).
 This class uses a provider-based architecture. To create a CertPathBuilder, call one of the static getInstance methods, passing in the algorithm name of the CertPathBuilder desired and optionally the name of the provider desired. 
Once a CertPathBuilder object has been created, certification paths can be constructed by calling the build method and passing it an algorithm-specific set of parameters. If successful, the result (including the CertPath that was built) is returned in an object that implements the CertPathBuilderResult interface. 
The getRevocationChecker method allows an application to specify additional algorithm-specific parameters and options used by the CertPathBuilder when checking the revocation status of certificates. Here is an example demonstrating how it is used with the PKIX algorithm: 
CertPathBuilder cpb = CertPathBuilder.getInstance("PKIX");
PKIXRevocationChecker rc = (PKIXRevocationChecker)cpb.getRevocationChecker();
rc.setOptions(EnumSet.of(Option.PREFER_CRLS));
params.addCertPathChecker(rc);
CertPathBuilderResult cpbr = cpb.build(params);

Every implementation of the Java platform is required to support the following standard CertPathBuilder algorithm: 

PKIX

This algorithm is described in the 
CertPathBuilder section of the
Java Security Standard Algorithm Names Specification.
Consult the release documentation for your implementation to see if any
other algorithms are supported.

Concurrent Access

The static methods of this class are guaranteed to be thread-safe.
Multiple threads may concurrently invoke the static methods defined in
this class with no ill effects.
 However, this is not true for the non-static methods defined by this class. Unless otherwise documented by a specific provider, threads that need to access a single CertPathBuilder instance concurrently should synchronize amongst themselves and provide the necessary locking. Multiple threads each manipulating a different CertPathBuilder instance need not synchronize. 
Author:
     Sean Mullan,      Yassir Elley
See Also:
CertPath
Since:
      1.4/**
 * A class for building certification paths (also known as certificate chains).
 * <p>
 * This class uses a provider-based architecture.
 * To create a {@code CertPathBuilder}, call
 * one of the static {@code getInstance} methods, passing in the
 * algorithm name of the {@code CertPathBuilder} desired and optionally
 * the name of the provider desired.
 *
 * <p>Once a {@code CertPathBuilder} object has been created, certification
 * paths can be constructed by calling the {@link #build build} method and
 * passing it an algorithm-specific set of parameters. If successful, the
 * result (including the {@code CertPath} that was built) is returned
 * in an object that implements the {@code CertPathBuilderResult}
 * interface.
 *
 * <p>The {@link #getRevocationChecker} method allows an application to specify
 * additional algorithm-specific parameters and options used by the
 * {@code CertPathBuilder} when checking the revocation status of certificates.
 * Here is an example demonstrating how it is used with the PKIX algorithm:
 *
 * <pre>
 * CertPathBuilder cpb = CertPathBuilder.getInstance("PKIX");
 * PKIXRevocationChecker rc = (PKIXRevocationChecker)cpb.getRevocationChecker();
 * rc.setOptions(EnumSet.of(Option.PREFER_CRLS));
 * params.addCertPathChecker(rc);
 * CertPathBuilderResult cpbr = cpb.build(params);
 * </pre>
 *
 * <p>Every implementation of the Java platform is required to support the
 * following standard {@code CertPathBuilder} algorithm:
 * <ul>
 * <li>{@code PKIX}</li>
 * </ul>
 * This algorithm is described in the <a href=
 * "{@docRoot}/../specs/security/standard-names.html#certpathbuilder-algorithms">
 * CertPathBuilder section</a> of the
 * Java Security Standard Algorithm Names Specification.
 * Consult the release documentation for your implementation to see if any
 * other algorithms are supported.
 *
 * <p>
 * <b>Concurrent Access</b>
 * <p>
 * The static methods of this class are guaranteed to be thread-safe.
 * Multiple threads may concurrently invoke the static methods defined in
 * this class with no ill effects.
 * <p>
 * However, this is not true for the non-static methods defined by this class.
 * Unless otherwise documented by a specific provider, threads that need to
 * access a single {@code CertPathBuilder} instance concurrently should
 * synchronize amongst themselves and provide the necessary locking. Multiple
 * threads each manipulating a different {@code CertPathBuilder} instance
 * need not synchronize.
 *
 * @see CertPath
 *
 * @since       1.4
 * @author      Sean Mullan
 * @author      Yassir Elley
 */
public class CertPathBuilder {

    /*
     * Constant to lookup in the Security properties file to determine
     * the default certpathbuilder type. In the Security properties file,
     * the default certpathbuilder type is given as:
     * <pre>
     * certpathbuilder.type=PKIX
     * </pre>
     */
    private static final String CPB_TYPE = "certpathbuilder.type";
    private final CertPathBuilderSpi builderSpi;
    private final Provider provider;
    private final String algorithm;

    
Creates a CertPathBuilder object of the given algorithm, and encapsulates the given provider implementation (SPI object) in it. 
Params:
builderSpi – the provider implementation
provider – the provider
algorithm – the algorithm name/**
     * Creates a {@code CertPathBuilder} object of the given algorithm,
     * and encapsulates the given provider implementation (SPI object) in it.
     *
     * @param builderSpi the provider implementation
     * @param provider the provider
     * @param algorithm the algorithm name
     */
    protected CertPathBuilder(CertPathBuilderSpi builderSpi, Provider provider,
        String algorithm)
    {
        this.builderSpi = builderSpi;
        this.provider = provider;
        this.algorithm = algorithm;
    }

    
Returns a CertPathBuilder object that implements the specified algorithm. 
 This method traverses the list of registered security Providers,
starting with the most preferred Provider.
A new CertPathBuilder object encapsulating the
CertPathBuilderSpi implementation from the first
Provider that supports the specified algorithm is returned.
 Note that the list of registered providers may be retrieved via the Security.getProviders() method. 
Params:
algorithm – the name of the requested CertPathBuilder algorithm. See the CertPathBuilder section in the 
Java Security Standard Algorithm Names Specification
for information about standard algorithm names.
Throws:
NoSuchAlgorithmException – if no Provider supports a CertPathBuilderSpi implementation for the specified algorithm
NullPointerException – if algorithm is null
See Also:
Provider
Implementation Note:
 The JDK Reference Implementation additionally uses the jdk.security.provider.preferred Security property to determine the preferred provider order for the specified algorithm. This may be different than the order of providers returned by Security.getProviders().
Returns:
a CertPathBuilder object that implements the specified algorithm/**
     * Returns a {@code CertPathBuilder} object that implements the
     * specified algorithm.
     *
     * <p> This method traverses the list of registered security Providers,
     * starting with the most preferred Provider.
     * A new CertPathBuilder object encapsulating the
     * CertPathBuilderSpi implementation from the first
     * Provider that supports the specified algorithm is returned.
     *
     * <p> Note that the list of registered providers may be retrieved via
     * the {@link Security#getProviders() Security.getProviders()} method.
     *
     * @implNote
     * The JDK Reference Implementation additionally uses the
     * {@code jdk.security.provider.preferred}
     * {@link Security#getProperty(String) Security} property to determine
     * the preferred provider order for the specified algorithm. This
     * may be different than the order of providers returned by
     * {@link Security#getProviders() Security.getProviders()}.
     *
     * @param algorithm the name of the requested {@code CertPathBuilder}
     *  algorithm.  See the CertPathBuilder section in the <a href=
     *  "{@docRoot}/../specs/security/standard-names.html#certpathbuilder-algorithms">
     * Java Security Standard Algorithm Names Specification</a>
     * for information about standard algorithm names.
     *
     * @return a {@code CertPathBuilder} object that implements the
     *         specified algorithm
     *
     * @throws NoSuchAlgorithmException if no {@code Provider} supports a
     *         {@code CertPathBuilderSpi} implementation for the
     *         specified algorithm
     *
     * @throws NullPointerException if {@code algorithm} is {@code null}
     *
     * @see java.security.Provider
     */
    public static CertPathBuilder getInstance(String algorithm)
            throws NoSuchAlgorithmException {
        Objects.requireNonNull(algorithm, "null algorithm name");
        Instance instance = GetInstance.getInstance("CertPathBuilder",
            CertPathBuilderSpi.class, algorithm);
        return new CertPathBuilder((CertPathBuilderSpi)instance.impl,
            instance.provider, algorithm);
    }

    
Returns a CertPathBuilder object that implements the specified algorithm. 
 A new CertPathBuilder object encapsulating the
CertPathBuilderSpi implementation from the specified provider
is returned.  The specified provider must be registered
in the security provider list.
 Note that the list of registered providers may be retrieved via the Security.getProviders() method. 
Params:
algorithm – the name of the requested CertPathBuilder algorithm. See the CertPathBuilder section in the 
Java Security Standard Algorithm Names Specification
for information about standard algorithm names.
provider – the name of the provider.
Throws:
IllegalArgumentException – if the provider is null or empty
NoSuchAlgorithmException – if a CertPathBuilderSpi implementation for the specified algorithm is not available from the specified provider
NoSuchProviderException – if the specified provider is not
        registered in the security provider list
NullPointerException – if algorithm is null
See Also:
Provider
Returns:
a CertPathBuilder object that implements the specified algorithm/**
     * Returns a {@code CertPathBuilder} object that implements the
     * specified algorithm.
     *
     * <p> A new CertPathBuilder object encapsulating the
     * CertPathBuilderSpi implementation from the specified provider
     * is returned.  The specified provider must be registered
     * in the security provider list.
     *
     * <p> Note that the list of registered providers may be retrieved via
     * the {@link Security#getProviders() Security.getProviders()} method.
     *
     * @param algorithm the name of the requested {@code CertPathBuilder}
     *  algorithm.  See the CertPathBuilder section in the <a href=
     *  "{@docRoot}/../specs/security/standard-names.html#certpathbuilder-algorithms">
     * Java Security Standard Algorithm Names Specification</a>
     * for information about standard algorithm names.
     *
     * @param provider the name of the provider.
     *
     * @return a {@code CertPathBuilder} object that implements the
     *         specified algorithm
     *
     * @throws IllegalArgumentException if the {@code provider} is
     *         {@code null} or empty
     *
     * @throws NoSuchAlgorithmException if a {@code CertPathBuilderSpi}
     *         implementation for the specified algorithm is not
     *         available from the specified provider
     *
     * @throws NoSuchProviderException if the specified provider is not
     *         registered in the security provider list
     *
     * @throws NullPointerException if {@code algorithm} is {@code null}
     *
     * @see java.security.Provider
     */
    public static CertPathBuilder getInstance(String algorithm, String provider)
           throws NoSuchAlgorithmException, NoSuchProviderException {
        Objects.requireNonNull(algorithm, "null algorithm name");
        Instance instance = GetInstance.getInstance("CertPathBuilder",
            CertPathBuilderSpi.class, algorithm, provider);
        return new CertPathBuilder((CertPathBuilderSpi)instance.impl,
            instance.provider, algorithm);
    }

    
Returns a CertPathBuilder object that implements the specified algorithm. 
 A new CertPathBuilder object encapsulating the
CertPathBuilderSpi implementation from the specified Provider
object is returned.  Note that the specified Provider object
does not have to be registered in the provider list.
Params:
algorithm – the name of the requested CertPathBuilder algorithm. See the CertPathBuilder section in the 
Java Security Standard Algorithm Names Specification
for information about standard algorithm names.
provider – the provider.
Throws:
IllegalArgumentException – if the provider is null
NoSuchAlgorithmException – if a CertPathBuilderSpi implementation for the specified algorithm is not available from the specified Provider object
NullPointerException – if algorithm is null
See Also:
Provider
Returns:
a CertPathBuilder object that implements the specified algorithm/**
     * Returns a {@code CertPathBuilder} object that implements the
     * specified algorithm.
     *
     * <p> A new CertPathBuilder object encapsulating the
     * CertPathBuilderSpi implementation from the specified Provider
     * object is returned.  Note that the specified Provider object
     * does not have to be registered in the provider list.
     *
     * @param algorithm the name of the requested {@code CertPathBuilder}
     *  algorithm.  See the CertPathBuilder section in the <a href=
     *  "{@docRoot}/../specs/security/standard-names.html#certpathbuilder-algorithms">
     * Java Security Standard Algorithm Names Specification</a>
     * for information about standard algorithm names.
     *
     * @param provider the provider.
     *
     * @return a {@code CertPathBuilder} object that implements the
     *         specified algorithm
     *
     * @throws IllegalArgumentException if the {@code provider} is
     *         {@code null}
     *
     * @throws NoSuchAlgorithmException if a {@code CertPathBuilderSpi}
     *         implementation for the specified algorithm is not available
     *         from the specified {@code Provider} object
     *
     * @throws NullPointerException if {@code algorithm} is {@code null}
     *
     * @see java.security.Provider
     */
    public static CertPathBuilder getInstance(String algorithm,
            Provider provider) throws NoSuchAlgorithmException {
        Objects.requireNonNull(algorithm, "null algorithm name");
        Instance instance = GetInstance.getInstance("CertPathBuilder",
            CertPathBuilderSpi.class, algorithm, provider);
        return new CertPathBuilder((CertPathBuilderSpi)instance.impl,
            instance.provider, algorithm);
    }

    
Returns the provider of this CertPathBuilder. 
Returns:
the provider of this CertPathBuilder/**
     * Returns the provider of this {@code CertPathBuilder}.
     *
     * @return the provider of this {@code CertPathBuilder}
     */
    public final Provider getProvider() {
        return this.provider;
    }

    
Returns the name of the algorithm of this CertPathBuilder. 
Returns:
the name of the algorithm of this CertPathBuilder/**
     * Returns the name of the algorithm of this {@code CertPathBuilder}.
     *
     * @return the name of the algorithm of this {@code CertPathBuilder}
     */
    public final String getAlgorithm() {
        return this.algorithm;
    }

    
Attempts to build a certification path using the specified algorithm
parameter set.
Params:
params – the algorithm parameters
Throws:
CertPathBuilderException – if the builder is unable to construct
 a certification path that satisfies the specified parameters
InvalidAlgorithmParameterException – if the specified parameters are inappropriate for this CertPathBuilder
Returns:
the result of the build algorithm/**
     * Attempts to build a certification path using the specified algorithm
     * parameter set.
     *
     * @param params the algorithm parameters
     * @return the result of the build algorithm
     * @throws CertPathBuilderException if the builder is unable to construct
     *  a certification path that satisfies the specified parameters
     * @throws InvalidAlgorithmParameterException if the specified parameters
     * are inappropriate for this {@code CertPathBuilder}
     */
    public final CertPathBuilderResult build(CertPathParameters params)
        throws CertPathBuilderException, InvalidAlgorithmParameterException
    {
        return builderSpi.engineBuild(params);
    }

    
Returns the default CertPathBuilder type as specified by the certpathbuilder.type security property, or the string "PKIX" if no such property exists. 
The default CertPathBuilder type can be used by applications that do not want to use a hard-coded type when calling one of the getInstance methods, and want to provide a default type in case a user does not specify its own. 
The default CertPathBuilder type can be changed by setting the value of the certpathbuilder.type security property to the desired type. 
See Also:
security properties
Returns:
the default CertPathBuilder type as specified by the certpathbuilder.type security property, or the string "PKIX" if no such property exists./**
     * Returns the default {@code CertPathBuilder} type as specified by
     * the {@code certpathbuilder.type} security property, or the string
     * {@literal "PKIX"} if no such property exists.
     *
     * <p>The default {@code CertPathBuilder} type can be used by
     * applications that do not want to use a hard-coded type when calling one
     * of the {@code getInstance} methods, and want to provide a default
     * type in case a user does not specify its own.
     *
     * <p>The default {@code CertPathBuilder} type can be changed by
     * setting the value of the {@code certpathbuilder.type} security property
     * to the desired type.
     *
     * @see java.security.Security security properties
     * @return the default {@code CertPathBuilder} type as specified
     * by the {@code certpathbuilder.type} security property, or the string
     * {@literal "PKIX"} if no such property exists.
     */
    public static final String getDefaultType() {
        String cpbtype =
            AccessController.doPrivileged(new PrivilegedAction<>() {
                public String run() {
                    return Security.getProperty(CPB_TYPE);
                }
            });
        return (cpbtype == null) ? "PKIX" : cpbtype;
    }

    
Returns a CertPathChecker that the encapsulated CertPathBuilderSpi implementation uses to check the revocation status of certificates. A PKIX implementation returns objects of type PKIXRevocationChecker. Each invocation of this method returns a new instance of CertPathChecker. 
The primary purpose of this method is to allow callers to specify
additional input parameters and options specific to revocation checking.
See the class description for an example.
Throws:
UnsupportedOperationException – if the service provider does not
        support this method
Returns:
a CertPathChecker
Since:
1.8/**
     * Returns a {@code CertPathChecker} that the encapsulated
     * {@code CertPathBuilderSpi} implementation uses to check the revocation
     * status of certificates. A PKIX implementation returns objects of
     * type {@code PKIXRevocationChecker}. Each invocation of this method
     * returns a new instance of {@code CertPathChecker}.
     *
     * <p>The primary purpose of this method is to allow callers to specify
     * additional input parameters and options specific to revocation checking.
     * See the class description for an example.
     *
     * @return a {@code CertPathChecker}
     * @throws UnsupportedOperationException if the service provider does not
     *         support this method
     * @since 1.8
     */
    public final CertPathChecker getRevocationChecker() {
        return builderSpi.engineGetRevocationChecker();
    }
}