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/*
* Copyright (C) 2013-2015 Dominik Schürmann <dominik@dominikschuermann.de>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.sufficientlysecure.keychain.util;
import android.content.res.AssetManager;
import com.squareup.okhttp.OkHttpClient;
import org.sufficientlysecure.keychain.Constants;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.security.KeyManagementException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.Certificate;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.util.HashMap;
import java.util.Map;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManagerFactory;
public class TlsHelper {
public static class TlsHelperException extends Exception {
public TlsHelperException(Exception e) {
super(e);
}
}
private static Map<String, byte[]> sPinnedCertificates = new HashMap<>();
/**
* Add certificate from assets to pinned certificate map.
*/
public static void addPinnedCertificate(String host, AssetManager assetManager, String cerFilename) {
try {
InputStream is = assetManager.open(cerFilename);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
int reads = is.read();
while (reads != -1) {
baos.write(reads);
reads = is.read();
}
is.close();
sPinnedCertificates.put(host, baos.toByteArray());
} catch (IOException e) {
Log.w(Constants.TAG, e);
}
}
/**
* Use pinned certificate for OkHttpClient if we have one.
*
* @return true, if certificate is available, false if not
* @throws TlsHelperException
* @throws IOException
*/
public static boolean usePinnedCertificateIfAvailable(OkHttpClient client, URL url) throws TlsHelperException, IOException {
if (url.getProtocol().equals("https")) {
// use certificate PIN from assets if we have one
for (String host : sPinnedCertificates.keySet()) {
if (url.getHost().endsWith(host)) {
pinCertificate(sPinnedCertificates.get(host), client);
return true;
}
}
}
return false;
}
/**
* Modifies the client to accept only requests with a given certificate. Applies to all URLs requested by the
* client.
* Therefore a client that is pinned this way should be used to only make requests to URLs with passed certificate.
*
* @param certificate certificate to pin
* @param client OkHttpClient to enforce pinning on
* @throws TlsHelperException
* @throws IOException
*/
private static void pinCertificate(byte[] certificate, OkHttpClient client)
throws TlsHelperException, IOException {
// We don't use OkHttp's CertificatePinner since it can not be used to pin self-signed
// certificate if such certificate is not accepted by TrustManager.
// (Refer to note at end of description:
// http://square.github.io/okhttp/javadoc/com/squareup/okhttp/CertificatePinner.html )
// Creating our own TrustManager that trusts only our certificate eliminates the need for certificate pinning
try {
// Load CA
CertificateFactory cf = CertificateFactory.getInstance("X.509");
Certificate ca = cf.generateCertificate(new ByteArrayInputStream(certificate));
// Create a KeyStore containing our trusted CAs
String keyStoreType = KeyStore.getDefaultType();
KeyStore keyStore = KeyStore.getInstance(keyStoreType);
keyStore.load(null, null);
keyStore.setCertificateEntry("ca", ca);
// Create a TrustManager that trusts the CAs in our KeyStore
String tmfAlgorithm = TrustManagerFactory.getDefaultAlgorithm();
TrustManagerFactory tmf = TrustManagerFactory.getInstance(tmfAlgorithm);
tmf.init(keyStore);
// Create an SSLContext that uses our TrustManager
SSLContext context = SSLContext.getInstance("TLS");
context.init(null, tmf.getTrustManagers(), null);
client.setSslSocketFactory(context.getSocketFactory());
} catch (CertificateException | KeyStoreException | KeyManagementException | NoSuchAlgorithmException e) {
throw new TlsHelperException(e);
}
}
}
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