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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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package java.security.cert;

import java.math.BigInteger;

import java.security.*;

import java.security.spec.*;

import java.util.Collection;

import java.util.Date;

import java.util.List;

import javax.security.auth.x500.X500Principal;

import sun.security.x509.X509CertImpl;

import sun.security.util.SignatureUtil;

/**

 * <p>

 * Abstract class for X.509 certificates. This provides a standard

 * way to access all the attributes of an X.509 certificate.

 * <p>

 * In June of 1996, the basic X.509 v3 format was completed by

 * ISO/IEC and ANSI X9, which is described below in ASN.1:

 * <pre>

 * Certificate  ::=  SEQUENCE  {

 *     tbsCertificate       TBSCertificate,

 *     signatureAlgorithm   AlgorithmIdentifier,

 *     signature            BIT STRING  }

 * </pre>

 * <p>

 * These certificates are widely used to support authentication and

 * other functionality in Internet security systems. Common applications

 * include Privacy Enhanced Mail (PEM), Transport Layer Security (SSL),

 * code signing for trusted software distribution, and Secure Electronic

 * Transactions (SET).

 * <p>

 * These certificates are managed and vouched for by <em>Certificate

 * Authorities</em> (CAs). CAs are services which create certificates by

 * placing data in the X.509 standard format and then digitally signing

 * that data. CAs act as trusted third parties, making introductions

 * between principals who have no direct knowledge of each other.

 * CA certificates are either signed by themselves, or by some other

 * CA such as a "root" CA.

 * <p>

 * More information can be found in

 * <a href="http://tools.ietf.org/html/rfc5280">RFC 5280: Internet X.509

 * Public Key Infrastructure Certificate and CRL Profile</a>.

 * <p>

 * The ASN.1 definition of {@code tbsCertificate} is:

 * <pre>

 * TBSCertificate  ::=  SEQUENCE  {

 *     version         [0]  EXPLICIT Version DEFAULT v1,

 *     serialNumber         CertificateSerialNumber,

 *     signature            AlgorithmIdentifier,

 *     issuer               Name,

 *     validity             Validity,

 *     subject              Name,

 *     subjectPublicKeyInfo SubjectPublicKeyInfo,

 *     issuerUniqueID  [1]  IMPLICIT UniqueIdentifier OPTIONAL,

 *                          -- If present, version must be v2 or v3

 *     subjectUniqueID [2]  IMPLICIT UniqueIdentifier OPTIONAL,

 *                          -- If present, version must be v2 or v3

 *     extensions      [3]  EXPLICIT Extensions OPTIONAL

 *                          -- If present, version must be v3

 *     }

 * </pre>

 * <p>

 * Certificates are instantiated using a certificate factory. The following is

 * an example of how to instantiate an X.509 certificate:

 * <pre>

 * try (InputStream inStream = new FileInputStream("fileName-of-cert")) {

 *     CertificateFactory cf = CertificateFactory.getInstance("X.509");

 *     X509Certificate cert = (X509Certificate)cf.generateCertificate(inStream);

 * }

 * </pre>

 *

 * @author Hemma Prafullchandra

 * @since 1.2

 *

 *

 * @see Certificate

 * @see CertificateFactory

 * @see X509Extension

 */

public abstract class X509Certificate extends Certificate

implements X509Extension {

    @java.io.Serial

    private static final long serialVersionUID = -2491127588187038216L;

    private transient X500Principal subjectX500Principal, issuerX500Principal;

    /**

     * Constructor for X.509 certificates.

     */

    protected X509Certificate() {

        super("X.509");

    }

    /**

     * Checks that the certificate is currently valid. It is if

     * the current date and time are within the validity period given in the

     * certificate.

     * <p>

     * The validity period consists of two date/time values:

     * the first and last dates (and times) on which the certificate

     * is valid. It is defined in

     * ASN.1 as:

     * <pre>

     * validity             Validity

     *

     * Validity ::= SEQUENCE {

     *     notBefore      CertificateValidityDate,

     *     notAfter       CertificateValidityDate }

     *

     * CertificateValidityDate ::= CHOICE {

     *     utcTime        UTCTime,

     *     generalTime    GeneralizedTime }

     * </pre>

     *

     * @throws    CertificateExpiredException if the certificate has expired.

     * @throws    CertificateNotYetValidException if the certificate is not

     * yet valid.

     */

    public abstract void checkValidity()

        throws CertificateExpiredException, CertificateNotYetValidException;

    /**

     * Checks that the given date is within the certificate's

     * validity period. In other words, this determines whether the

     * certificate would be valid at the given date/time.

     *

     * @param date the Date to check against to see if this certificate

     *        is valid at that date/time.

     *

     * @throws    CertificateExpiredException if the certificate has expired

     * with respect to the {@code date} supplied.

     * @throws    CertificateNotYetValidException if the certificate is not

     * yet valid with respect to the {@code date} supplied.

     *

     * @see #checkValidity()

     */

    public abstract void checkValidity(Date date)

        throws CertificateExpiredException, CertificateNotYetValidException;

    /**

     * Gets the {@code version} (version number) value from the

     * certificate.

     * The ASN.1 definition for this is:

     * <pre>

     * version  [0] EXPLICIT Version DEFAULT v1

     *

     * Version ::=  INTEGER  {  v1(0), v2(1), v3(2)  }

     * </pre>

     * @return the version number, i.e. 1, 2 or 3.

     */

    public abstract int getVersion();

    /**

     * Gets the {@code serialNumber} value from the certificate.

     * The serial number is an integer assigned by the certification

     * authority to each certificate. It must be unique for each

     * certificate issued by a given CA (i.e., the issuer name and

     * serial number identify a unique certificate).

     * The ASN.1 definition for this is:

     * <pre>

     * serialNumber     CertificateSerialNumber

     *

     * CertificateSerialNumber  ::=  INTEGER

     * </pre>

     *

     * @return the serial number.

     */

    public abstract BigInteger getSerialNumber();

    /**

     * <strong>Denigrated</strong>, replaced by {@linkplain

     * #getIssuerX500Principal()}. This method returns the {@code issuer}

     * as an implementation specific Principal object, which should not be

     * relied upon by portable code.

     *

     * <p>

     * Gets the {@code issuer} (issuer distinguished name) value from

     * the certificate. The issuer name identifies the entity that signed (and

     * issued) the certificate.

     *

     * <p>The issuer name field contains an

     * X.500 distinguished name (DN).

     * The ASN.1 definition for this is:

     * <pre>

     * issuer    Name

     *

     * Name ::= CHOICE { RDNSequence }

     * RDNSequence ::= SEQUENCE OF RelativeDistinguishedName

     * RelativeDistinguishedName ::=

     *     SET OF AttributeValueAssertion

     *

     * AttributeValueAssertion ::= SEQUENCE {

     *                               AttributeType,

     *                               AttributeValue }

     * AttributeType ::= OBJECT IDENTIFIER

     * AttributeValue ::= ANY

     * </pre>

     * The {@code Name} describes a hierarchical name composed of

     * attributes,

     * such as country name, and corresponding values, such as US.

     * The type of the {@code AttributeValue} component is determined by

     * the {@code AttributeType}; in general it will be a

     * {@code directoryString}. A {@code directoryString} is usually

     * one of {@code PrintableString},

     * {@code TeletexString} or {@code UniversalString}.

     *

     * @return a Principal whose name is the issuer distinguished name.

     */

    public abstract Principal getIssuerDN();

    /**

     * Returns the issuer (issuer distinguished name) value from the

     * certificate as an {@code X500Principal}.

     * <p>

     * It is recommended that subclasses override this method.

     *

     * @return an {@code X500Principal} representing the issuer

     *          distinguished name

     * @since 1.4

     */

    public X500Principal getIssuerX500Principal() {

        if (issuerX500Principal == null) {

            issuerX500Principal = X509CertImpl.getIssuerX500Principal(this);

        }

        return issuerX500Principal;

    }

    /**

     * <strong>Denigrated</strong>, replaced by {@linkplain

     * #getSubjectX500Principal()}. This method returns the {@code subject}

     * as an implementation specific Principal object, which should not be

     * relied upon by portable code.

     *

     * <p>

     * Gets the {@code subject} (subject distinguished name) value

     * from the certificate.  If the {@code subject} value is empty,

     * then the {@code getName()} method of the returned

     * {@code Principal} object returns an empty string ("").

     *

     * <p> The ASN.1 definition for this is:

     * <pre>

     * subject    Name

     * </pre>

     *

     * <p>See {@link #getIssuerDN() getIssuerDN} for {@code Name}

     * and other relevant definitions.

     *

     * @return a Principal whose name is the subject name.

     */

    public abstract Principal getSubjectDN();

    /**

     * Returns the subject (subject distinguished name) value from the

     * certificate as an {@code X500Principal}.  If the subject value

     * is empty, then the {@code getName()} method of the returned

     * {@code X500Principal} object returns an empty string ("").

     * <p>

     * It is recommended that subclasses override this method.

     *

     * @return an {@code X500Principal} representing the subject

     *          distinguished name

     * @since 1.4

     */

    public X500Principal getSubjectX500Principal() {

        if (subjectX500Principal == null) {

            subjectX500Principal = X509CertImpl.getSubjectX500Principal(this);

        }

        return subjectX500Principal;

    }

    /**

     * Gets the {@code notBefore} date from the validity period of

     * the certificate.

     * The relevant ASN.1 definitions are:

     * <pre>

     * validity             Validity

     *

     * Validity ::= SEQUENCE {

     *     notBefore      CertificateValidityDate,

     *     notAfter       CertificateValidityDate }

     *

     * CertificateValidityDate ::= CHOICE {

     *     utcTime        UTCTime,

     *     generalTime    GeneralizedTime }

     * </pre>

     *

     * @return the start date of the validity period.

     * @see #checkValidity

     */

    public abstract Date getNotBefore();

    /**

     * Gets the {@code notAfter} date from the validity period of

     * the certificate. See {@link #getNotBefore() getNotBefore}

     * for relevant ASN.1 definitions.

     *

     * @return the end date of the validity period.

     * @see #checkValidity

     */

    public abstract Date getNotAfter();

    /**

     * Gets the DER-encoded certificate information, the

     * {@code tbsCertificate} from this certificate.

     * This can be used to verify the signature independently.

     *

     * @return the DER-encoded certificate information.

     * @throws    CertificateEncodingException if an encoding error occurs.

     */

    public abstract byte[] getTBSCertificate()

        throws CertificateEncodingException;

    /**

     * Gets the {@code signature} value (the raw signature bits) from

     * the certificate.

     * The ASN.1 definition for this is:

     * <pre>

     * signature     BIT STRING

     * </pre>

     *

     * @return the signature.

     */

    public abstract byte[] getSignature();

    /**

     * Gets the signature algorithm name for the certificate

     * signature algorithm. An example is the string "SHA256withRSA".

     * The ASN.1 definition for this is:

     * <pre>

     * signatureAlgorithm   AlgorithmIdentifier

     *

     * AlgorithmIdentifier  ::=  SEQUENCE  {

     *     algorithm               OBJECT IDENTIFIER,

     *     parameters              ANY DEFINED BY algorithm OPTIONAL  }

     *                             -- contains a value of the type

     *                             -- registered for use with the

     *                             -- algorithm object identifier value

     * </pre>

     *

     * <p>The algorithm name is determined from the {@code algorithm}

     * OID string.

     *

     * @return the signature algorithm name.

     */

    public abstract String getSigAlgName();

    /**

     * Gets the signature algorithm OID string from the certificate.

     * An OID is represented by a set of nonnegative whole numbers separated

     * by periods.

     * For example, the string "1.2.840.10040.4.3" identifies the SHA-1

     * with DSA signature algorithm defined in

     * <a href="http://www.ietf.org/rfc/rfc3279.txt">RFC 3279: Algorithms and

     * Identifiers for the Internet X.509 Public Key Infrastructure Certificate

     * and CRL Profile</a>.

     *

     * <p>See {@link #getSigAlgName() getSigAlgName} for

     * relevant ASN.1 definitions.

     *

     * @return the signature algorithm OID string.

     */

    public abstract String getSigAlgOID();

    /**

     * Gets the DER-encoded signature algorithm parameters from this

     * certificate's signature algorithm. In most cases, the signature

     * algorithm parameters are null; the parameters are usually

     * supplied with the certificate's public key.

     * If access to individual parameter values is needed then use

     * {@link java.security.AlgorithmParameters AlgorithmParameters}

     * and instantiate with the name returned by

     * {@link #getSigAlgName() getSigAlgName}.

     *

     * <p>See {@link #getSigAlgName() getSigAlgName} for

     * relevant ASN.1 definitions.

     *

     * @return the DER-encoded signature algorithm parameters, or

     *         null if no parameters are present.

     */

    public abstract byte[] getSigAlgParams();

    /**

     * Gets the {@code issuerUniqueID} value from the certificate.

     * The issuer unique identifier is present in the certificate

     * to handle the possibility of reuse of issuer names over time.

     * RFC 5280 recommends that names not be reused and that

     * conforming certificates not make use of unique identifiers.

     * Applications conforming to that profile should be capable of

     * parsing unique identifiers and making comparisons.

     *

     * <p>The ASN.1 definition for this is:

     * <pre>

     * issuerUniqueID  [1]  IMPLICIT UniqueIdentifier OPTIONAL

     *

     * UniqueIdentifier  ::=  BIT STRING

     * </pre>

     *

     * @return the issuer unique identifier or null if it is not

     * present in the certificate.

     */

    public abstract boolean[] getIssuerUniqueID();

    /**

     * Gets the {@code subjectUniqueID} value from the certificate.

     *

     * <p>The ASN.1 definition for this is:

     * <pre>

     * subjectUniqueID  [2]  IMPLICIT UniqueIdentifier OPTIONAL

     *

     * UniqueIdentifier  ::=  BIT STRING

     * </pre>

     *

     * @return the subject unique identifier or null if it is not

     * present in the certificate.

     */

    public abstract boolean[] getSubjectUniqueID();

    /**

     * Gets a boolean array representing bits of

     * the {@code KeyUsage} extension, (OID = 2.5.29.15).

     * The key usage extension defines the purpose (e.g., encipherment,

     * signature, certificate signing) of the key contained in the

     * certificate.

     * The ASN.1 definition for this is:

     * <pre>

     * KeyUsage ::= BIT STRING {

     *     digitalSignature        (0),

     *     nonRepudiation          (1),

     *     keyEncipherment         (2),

     *     dataEncipherment        (3),

     *     keyAgreement            (4),

     *     keyCertSign             (5),

     *     cRLSign                 (6),

     *     encipherOnly            (7),

     *     decipherOnly            (8) }

     * </pre>

     * RFC 5280 recommends that when used, this be marked

     * as a critical extension.

     *

     * @return the KeyUsage extension of this certificate, represented as

     * an array of booleans. The order of KeyUsage values in the array is

     * the same as in the above ASN.1 definition. The array will contain a

     * value for each KeyUsage defined above. If the KeyUsage list encoded

     * in the certificate is longer than the above list, it will not be

     * truncated. Returns null if this certificate does not

     * contain a KeyUsage extension.

     */

    public abstract boolean[] getKeyUsage();

    /**

     * Gets an unmodifiable list of Strings representing the OBJECT

     * IDENTIFIERs of the {@code ExtKeyUsageSyntax} field of the

     * extended key usage extension, (OID = 2.5.29.37).  It indicates

     * one or more purposes for which the certified public key may be

     * used, in addition to or in place of the basic purposes

     * indicated in the key usage extension field.  The ASN.1

     * definition for this is:

     * <pre>

     * ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId

     *

     * KeyPurposeId ::= OBJECT IDENTIFIER

     * </pre>

     *

     * Key purposes may be defined by any organization with a

     * need. Object identifiers used to identify key purposes shall be

     * assigned in accordance with IANA or ITU-T Rec. X.660 |

     * ISO/IEC/ITU 9834-1.

     * <p>

     * This method was added to version 1.4 of the Java 2 Platform Standard

     * Edition. In order to maintain backwards compatibility with existing

     * service providers, this method is not {@code abstract}

     * and it provides a default implementation. Subclasses

     * should override this method with a correct implementation.

     *

     * @return the ExtendedKeyUsage extension of this certificate,

     *         as an unmodifiable list of object identifiers represented

     *         as Strings. Returns null if this certificate does not

     *         contain an ExtendedKeyUsage extension.

     * @throws CertificateParsingException if the extension cannot be decoded

     * @since 1.4

     */

    public List<String> getExtendedKeyUsage() throws CertificateParsingException {

        return X509CertImpl.getExtendedKeyUsage(this);

    }

    /**

     * Gets the certificate constraints path length from the