Android Context Check isValidSigningKey(final Context context, final String certificateToCheckAgainst)

Description

Check whether the signing key can be validated.

License

Apache License

Parameter

Parameter	Description
context	Context
certificateToCheckAgainst	the SHA1 of the signing certificate

Return

true when the signing key appears valid, otherwise false

Declaration

public static boolean isValidSigningKey(final Context context,
        final String certificateToCheckAgainst) 

Method Source Code

//package com.java2s;
//License from project: Apache License 

import android.content.Context;

import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.Signature;

import java.io.ByteArrayInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateEncodingException;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;

public class Main {
    /**/* ww  w  .j a  v  a 2 s. com*/
     * Check whether the signing key can be validated.
     *
     * @param context Context
     * @param certificateToCheckAgainst the SHA1 of the signing certificate
     * @return true when the signing key appears valid, otherwise false
     */
    public static boolean isValidSigningKey(final Context context,
            final String certificateToCheckAgainst) {
        try {
            Signature[] signatures = getSignatures(context);
            for (int i = 0; i < signatures.length; i++) {
                X509Certificate certificate = generateX509CertificateFromSignature(signatures[i]);
                String sha1 = getCertificateSHA1(certificate);
                if (!certificateToCheckAgainst.equalsIgnoreCase(sha1)) {
                    return false;
                }
            }
        } catch (PackageManager.NameNotFoundException e) {
            // package not found - leave valid true
        } catch (CertificateException e) {
            // certificate factory non-instantiable - leave valid true
        } catch (NoSuchAlgorithmException e) {
            // algorithm not found - leave valid true
        }
        return true;
    }

    private static Signature[] getSignatures(final Context context)
            throws PackageManager.NameNotFoundException {
        PackageInfo packageInfo = context.getPackageManager()
                .getPackageInfo(getPackageName(context),
                        PackageManager.GET_SIGNATURES);
        Signature[] signatures = packageInfo.signatures;
        return signatures;
    }

    private static X509Certificate generateX509CertificateFromSignature(
            final Signature signature) throws CertificateException {
        CertificateFactory certificateFactory = CertificateFactory
                .getInstance("X.509");
        ByteArrayInputStream inputStream = new ByteArrayInputStream(
                signature.toByteArray());
        X509Certificate certificate = (X509Certificate) certificateFactory
                .generateCertificate(inputStream);
        return certificate;
    }

    private static String getCertificateSHA1(X509Certificate certificate)
            throws NoSuchAlgorithmException, CertificateEncodingException {
        MessageDigest messageDigest = MessageDigest.getInstance("SHA-1");
        byte[] der = certificate.getEncoded();
        messageDigest.update(der);
        byte[] digest = messageDigest.digest();
        return hexify(digest);
    }

    /**
     * Get the application package name.
     *
     * @param context Context
     * @return package name
     */
    public static String getPackageName(final Context context) {
        return context.getPackageName();
    }

    private static String hexify(byte bytes[]) {
        char[] hexDigits = { '0', '1', '2', '3', '4', '5', '6', '7', '8',
                '9', 'a', 'b', 'c', 'd', 'e', 'f' };

        StringBuffer buf = new StringBuffer(bytes.length * 2);
        for (int i = 0; i < bytes.length; ++i) {
            buf.append(hexDigits[(bytes[i] & 0xf0) >> 4]);
            buf.append(hexDigits[bytes[i] & 0x0f]);
        }
        return buf.toString();
    }
}

Related

1. isSystemApplication(Context context, String packageName)
2. isTablet(Context ctx)
3. isTablet(final Context context)
4. isThemeInstalled(Context c, String theme)
5. isUpdateAvailable(Context paramContext, String paramString)
6. isVoiceSearchServiceExist(Context context)