uk.ac.cam.gpe21.droidssl.mitm.crypto.cert.CertificateUtils.java Source code

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Here is the source code for uk.ac.cam.gpe21.droidssl.mitm.crypto.cert.CertificateUtils.java

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/*
 * Copyright 2013-2014 Graham Edgecombe
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package uk.ac.cam.gpe21.droidssl.mitm.crypto.cert;

import org.bouncycastle.asn1.x500.AttributeTypeAndValue;
import org.bouncycastle.asn1.x500.RDN;
import org.bouncycastle.asn1.x500.X500Name;
import org.bouncycastle.asn1.x500.style.BCStyle;
import org.bouncycastle.cert.X509CertificateHolder;
import org.bouncycastle.cert.jcajce.JcaX500NameUtil;
import org.bouncycastle.cert.jcajce.JcaX509CertificateConverter;
import org.bouncycastle.openssl.PEMParser;

import java.io.IOException;
import java.io.Reader;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.security.cert.CertificateException;
import java.security.cert.CertificateParsingException;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

public final class CertificateUtils {
    private static final String[] EMPTY_STRING_ARRAY = new String[0];

    public static X509Certificate readCertificate(Path path) throws IOException {
        try (Reader reader = Files.newBufferedReader(path, StandardCharsets.UTF_8)) {
            return readCertificate(reader);
        }
    }

    public static X509Certificate readCertificate(Reader reader) throws IOException {
        // TODO share with CertificateAuthority's own implementation
        try (PEMParser parser = new PEMParser(reader)) {
            Object object = parser.readObject();
            if (!(object instanceof X509CertificateHolder))
                throw new IOException("File does not contain a certificate");

            X509CertificateHolder certificate = (X509CertificateHolder) object;
            return new JcaX509CertificateConverter().getCertificate(certificate);
        } catch (CertificateException ex) {
            throw new IOException(ex);
        }
    }

    public static String extractCn(X509Certificate certificate) {
        X500Name dn = JcaX500NameUtil.getSubject(certificate);
        for (RDN rdn : dn.getRDNs()) {
            AttributeTypeAndValue first = rdn.getFirst();
            if (first.getType().equals(BCStyle.CN)) {
                return first.getValue().toString();
            }
        }

        throw new IllegalArgumentException("certificate subject has no common name (CN)");
    }

    public static String[] extractSans(X509Certificate certificate) {
        try {
            Collection<List<?>> pairs = certificate.getSubjectAlternativeNames();
            if (pairs == null)
                return EMPTY_STRING_ARRAY;

            List<String> sans = new ArrayList<>();
            for (List<?> pair : pairs) {
                int type = (Integer) pair.get(0);
                if (type == 2) { // TODO fix magic number!
                    String san = (String) pair.get(1);
                    sans.add(san);
                }
            }
            return sans.toArray(EMPTY_STRING_ARRAY);
        } catch (CertificateParsingException ex) {
            throw new IllegalArgumentException(ex); // TODO ideal?
        }
    }

    private CertificateUtils() {
        /* to prevent instantiation */
    }
}