Use this piece of code because is more reliable, i tried many versions of openssl but with no success.
try {
PackageInfo info = getPackageManager().getPackageInfo("your.package",
PackageManager.GET_SIGNATURES);
for (Signature signature : info.signatures) {
MessageDigest md = MessageDigest.getInstance("SHA");
md.update(signature.toByteArray());
Log.d("YOURHASH KEY:",
Base64.encodeToString(md.digest(), Base64.DEFAULT));
}
} catch (NameNotFoundException e) {
} catch (NoSuchAlgorithmException e) {
}
paste it in onCreate