How to get APK signing signature?

Question

Is there a way to retrieve the signature of the key used to sign an APK? I signed my APK with my key from my keystore. How can I retrieve it programmatically?

Answer 1

The package manager will give you the signing certificate for any installed package. You can then print out the details of the signing key, e.g.

final PackageManager packageManager = context.getPackageManager();
final List packageList = packageManager.getInstalledPackages(PackageManager.GET_SIGNATURES);

for (PackageInfo p : packageList) {
    final String strName = p.applicationInfo.loadLabel(packageManager).toString();
    final String strVendor = p.packageName;

    sb.append("
" + strName + " / " + strVendor + "
");

    final Signature[] arrSignatures = p.signatures;
    for (final Signature sig : arrSignatures) {
        /*
        * Get the X.509 certificate.
        */
        final byte[] rawCert = sig.toByteArray();
        InputStream certStream = new ByteArrayInputStream(rawCert);

        try {
            CertificateFactory certFactory = CertificateFactory.getInstance("X509");
            X509Certificate x509Cert = (X509Certificate) certFactory.generateCertificate(certStream);

            sb.append("Certificate subject: " + x509Cert.getSubjectDN() + "
");
            sb.append("Certificate issuer: " + x509Cert.getIssuerDN() + "
");
            sb.append("Certificate serial number: " + x509Cert.getSerialNumber() + "
");
            sb.append("
");
        }
        catch (CertificateException e) {
            // e.printStackTrace();
        }
    }
}