Verifying App Signature - Tamper Detection

suggest change

This technique details how to ensure that your .apk has been signed with your developer certificate, and leverages the fact that the certificate remains consistent and that only you have access to it. We can break this technique into 3 simple steps:

Here’s the code snippet:

private static final int VALID = 0;
private static final int INVALID = 1;

public static int checkAppSignature(Context context) {

try {
      PackageInfo packageInfo = context.getPackageManager().getPackageInfo(context.getPackageName(), PackageManager.GET_SIGNATURES);

      for (Signature signature : packageInfo.signatures) {

        byte[] signatureBytes = signature.toByteArray();

        MessageDigest md = MessageDigest.getInstance("SHA");


        final String currentSignature = Base64.encodeToString(md.digest(), Base64.DEFAULT);

        Log.d("REMOVE_ME", "Include this string as a value for SIGNATURE:" + currentSignature);

        //compare signatures
        if (SIGNATURE.equals(currentSignature)){
          return VALID;
    } catch (Exception e) {
        //assumes an issue in checking signature., but we let the caller decide on what to do.

    return INVALID;


Feedback about page:

Optional: your email if you want me to get back to you:

Table Of Contents