src/java.base/share/classes/sun/security/util/UntrustedCertificates.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * accompanied this code).
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package sun.security.util;

import java.io.*;
import java.security.cert.X509Certificate;
import java.util.Properties;

import jdk.internal.util.StaticProperty;
import sun.security.x509.X509CertImpl;

/**
 * A utility class to check if a certificate is untrusted. This is an internal
 * mechanism that explicitly marks a certificate as untrusted, normally in the
 * case that a certificate is known to be used for malicious reasons.
 *
 * <b>Attention</b>: This check is NOT meant to replace the standard PKI-defined
 * validation check, neither is it used as an alternative to CRL.
 */
public final class UntrustedCertificates {

    private static final Debug debug = Debug.getInstance("certpath");
    private static final String ALGORITHM_KEY = "Algorithm";

    private static final Properties props = new Properties();
    private static final String algorithm;

    static {
        File f = new File(StaticProperty.javaHome(),
                "lib/security/blocked.certs");
        try (FileInputStream fin = new FileInputStream(f)) {
            props.load(fin);
        } catch (IOException fnfe) {
            if (debug != null) {
                debug.println("Error parsing blocked.certs");
            }
        }
        algorithm = props.getProperty(ALGORITHM_KEY);
    }

    /**
     * Checks if a certificate is untrusted.
     *
     * @param cert the certificate to check
     * @return true if the certificate is untrusted.
     */
    public static boolean isUntrusted(X509Certificate cert) {
        if (algorithm == null) {
            return false;
        }
        // if fingerprint cannot be calculated, also treat it as untrusted
        String key = X509CertImpl.getFingerprint(algorithm, cert, debug);
        return (key == null || props.containsKey(key));
    }

    private UntrustedCertificates() {}
}