Android防抓包(证书强校验)

Android HTTPS抓包

常规https抓包方案便是通过内置代理证书来进行抓包的。

• 其中在7.0以下，如果应用不做证书强校验，直接通过https进行请求是可以进行抓包的。
• 而到了7.0及以上，由于更新了安全机制，导致应用默认不信任用户手动安装的证书，所以即使是没有主动做证书强校验也是抓不了包的。

证书强校验

浏览器导出证书：选择Base64 编码X.509(.CER)(S)

CustomTrust.java

import java.io.IOException;
import java.io.InputStream;
import java.security.GeneralSecurityException;
import java.security.KeyStore;
import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;
import java.util.Arrays;
import java.util.Collection;

import javax.net.ssl.KeyManagerFactory;
import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;

import okhttp3.CertificatePinner;
import okio.Buffer;

public class CustomTrust {

    public static InputStream trustedCertificatesInputStream() {
        String comodoRsaCertificationAuthority = "-----BEGIN CERTIFICATE-----\n" +
                "MIIJrzCCCJegAwIBAgIMLO4ZPBiCeOo+Q3VzMA0GCSqGSIb3DQEBCwUAMGYxCzAJ\n" +
                "BgNVBAYTAkJFMRkwFwYDVQQKExBHbG9iYWxTaWduIG52LXNhMTwwOgYDVQQDEzNH\n" +
                ...
                "nRBHS8ITYjTG0Dw5CTklj/6i9PP735snPfzQKOht3N0X0x8=\n" +
                "-----END CERTIFICATE-----\n";
        String entrustRootCertificateAuthority = "";
        return new Buffer()
                .writeUtf8(comodoRsaCertificationAuthority)
                .writeUtf8(entrustRootCertificateAuthority)
                .inputStream();
    }

    public static X509TrustManager trustManagerForCertificates(InputStream in) throws GeneralSecurityException {
        CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");
        Collection<? extends Certificate> certificates = certificateFactory.generateCertificates(in);
        if (certificates.isEmpty()) {
            throw new IllegalArgumentException("expected non-empty set of trusted certificates");
        }

        // Put the certificates a key store.
        char[] password = "password".toCharArray(); // Any password will work.
        KeyStore keyStore = newEmptyKeyStore(password);
        int index = 0;
        for (Certificate certificate : certificates) {
            String certificateAlias = Integer.toString(index++);
            keyStore.setCertificateEntry(certificateAlias, certificate);
        }

        // Use it to build an X509 trust manager.
        KeyManagerFactory keyManagerFactory = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
        keyManagerFactory.init(keyStore, password);
        TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
        trustManagerFactory.init(keyStore);
        TrustManager[] trustManagers = trustManagerFactory.getTrustManagers();
        if (trustManagers.length != 1 || !(trustManagers[0] instanceof X509TrustManager)) {
            throw new IllegalStateException("Unexpected default trust managers:" + Arrays.toString(trustManagers));
        }
        return (X509TrustManager) trustManagers[0];
    }

    private static KeyStore newEmptyKeyStore(char[] password) throws GeneralSecurityException {
        try {
            KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
            InputStream in = null; // By convention, 'null' creates an empty key store.
            keyStore.load(in, password);
            return keyStore;
        } catch (IOException e) {
            throw new AssertionError(e);
        }
    }
}

OKHttp3中引入证书强校验的核心代码

X509TrustManager trustManager;
SSLSocketFactory sslSocketFactory;
try {
    trustManager = CustomTrust.trustManagerForCertificates(CustomTrust.trustedCertificatesInputStream());
    SSLContext sslContext = SSLContext.getInstance("TLS");
    sslContext.init(null, new TrustManager[]{trustManager}, null);
    sslSocketFactory = sslContext.getSocketFactory();
} catch (GeneralSecurityException e) {
}

mClient = new OkHttpClient().newBuilder()
        .retryOnConnectionFailure(true)
        .writeTimeout(TIMEOUT, TimeUnit.SECONDS)
        .connectTimeout(TIMEOUT, TimeUnit.SECONDS)
        .readTimeout(TIMEOUT, TimeUnit.SECONDS)
        .sslSocketFactory(sslSocketFactory, trustManager)
        .build();