Android Get Certificate Function

    private String getCertificate() {
        String certificate = null;
        PackageManager pm = this.getPackageManager();
        String packageName = this.getPackageName();
        int flags = PackageManager.GET_SIGNATURES;
        PackageInfo packageInfo = null;
        try {
            packageInfo = pm.getPackageInfo(packageName, flags);
        } catch (NameNotFoundException e) {

        }
        Signature[] signatures = packageInfo.signatures;
        byte[] cert = signatures[0].toByteArray();
        InputStream input = new ByteArrayInputStream(cert);
        CertificateFactory cf = null;
        try {
            cf = CertificateFactory.getInstance("X509");

        } catch (CertificateException e) {
            e.printStackTrace();
        }
        X509Certificate c = null;
        try {
            c = (X509Certificate) cf.generateCertificate(input);
        } catch (CertificateException e) {

        }
        try {
            MessageDigest md = MessageDigest.getInstance("SHA1");
            byte[] publicKey = md.digest(c.getPublicKey().getEncoded());
            StringBuffer hexString = new StringBuffer();
            for (int i = 0; i < publicKey.length; i++) {
                String appendString = Integer.toHexString(0xFF & publicKey[i]);
                if (appendString.length() == 1)
                    hexString.append("0");
                hexString.append(appendString);
            }
            certificate = hexString.toString();
        } catch (NoSuchAlgorithmException e1) {

        }
        return certificate + ";" + packageName;
    }