141 lines
5.2 KiB
Java
141 lines
5.2 KiB
Java
/*
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* Copyright (C) 2017 Schürmann & Breitmoser GbR
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package org.sufficientlysecure.keychain.network;
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import android.content.res.AssetManager;
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import java.io.ByteArrayInputStream;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import java.net.URL;
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import java.security.KeyManagementException;
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import java.security.KeyStore;
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import java.security.KeyStoreException;
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import java.security.NoSuchAlgorithmException;
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import java.security.cert.Certificate;
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import java.security.cert.CertificateException;
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import java.security.cert.CertificateFactory;
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import java.util.Arrays;
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import java.util.HashMap;
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import java.util.Map;
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import javax.net.ssl.SSLContext;
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import javax.net.ssl.SSLSocketFactory;
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import javax.net.ssl.TrustManager;
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import javax.net.ssl.TrustManagerFactory;
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import javax.net.ssl.X509TrustManager;
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import okhttp3.OkHttpClient;
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import timber.log.Timber;
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public class TlsCertificatePinning {
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private static Map<String, byte[]> sCertificatePins = new HashMap<>();
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/**
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* Add certificate from assets to pinned certificate map.
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*/
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public static void addPinnedCertificate(String host, AssetManager assetManager, String cerFilename) {
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try {
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InputStream is = assetManager.open(cerFilename);
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ByteArrayOutputStream baos = new ByteArrayOutputStream();
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int reads = is.read();
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while (reads != -1) {
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baos.write(reads);
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reads = is.read();
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}
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is.close();
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sCertificatePins.put(host, baos.toByteArray());
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} catch (IOException e) {
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Timber.w(e);
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}
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}
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private final URL url;
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public TlsCertificatePinning(URL url) {
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this.url = url;
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}
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public boolean isPinAvailable() {
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return sCertificatePins.containsKey(url.getHost());
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}
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/**
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* Modifies the builder to accept only requests with a given certificate.
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* Applies to all URLs requested by the builder.
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* Therefore a builder that is pinned this way should be used to only make requests
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* to URLs with passed certificate.
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*/
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void pinCertificate(OkHttpClient.Builder builder) {
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Timber.d("Pinning certificate for " + url);
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// We don't use OkHttp's CertificatePinner since it can not be used to pin self-signed
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// certificate if such certificate is not accepted by TrustManager.
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// (Refer to note at end of description:
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// http://square.github.io/okhttp/javadoc/com/squareup/okhttp/CertificatePinner.html )
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// Creating our own TrustManager that trusts only our certificate eliminates the need for certificate pinning
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try {
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CertificateFactory cf = CertificateFactory.getInstance("X.509");
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byte[] certificate = sCertificatePins.get(url.getHost());
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Certificate ca = cf.generateCertificate(new ByteArrayInputStream(certificate));
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KeyStore keyStore = createSingleCertificateKeyStore(ca);
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X509TrustManager trustManager = createTrustManager(keyStore);
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SSLContext sslContext = SSLContext.getInstance("TLS");
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sslContext.init(null, new TrustManager[]{trustManager}, null);
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SSLSocketFactory sslSocketFactory = sslContext.getSocketFactory();
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builder.sslSocketFactory(sslSocketFactory, trustManager);
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} catch (CertificateException | KeyStoreException |
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KeyManagementException | NoSuchAlgorithmException | IOException e) {
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throw new IllegalStateException(e);
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}
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}
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private KeyStore createSingleCertificateKeyStore(Certificate ca) throws KeyStoreException,
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CertificateException, NoSuchAlgorithmException, IOException {
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String keyStoreType = KeyStore.getDefaultType();
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KeyStore keyStore = KeyStore.getInstance(keyStoreType);
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keyStore.load(null, null);
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keyStore.setCertificateEntry("ca", ca);
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return keyStore;
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}
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private X509TrustManager createTrustManager(KeyStore keyStore) throws NoSuchAlgorithmException,
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KeyStoreException {
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TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(
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TrustManagerFactory.getDefaultAlgorithm());
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trustManagerFactory.init(keyStore);
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TrustManager[] trustManagers = trustManagerFactory.getTrustManagers();
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if (trustManagers.length != 1 || !(trustManagers[0] instanceof X509TrustManager)) {
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throw new IllegalStateException("Unexpected default trust managers: "
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+ Arrays.toString(trustManagers));
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}
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return (X509TrustManager) trustManagers[0];
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}
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}
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