So I found a solution:
#!/usr/bin/env python
import sys
import subprocess
import re
import os
app_path = os.path.abspath(sys.argv[1])
signing_info = subprocess.Popen(['codesign', '--display', '--verbose=4', app_path], stdin=subprocess.PIPE, stderr=subprocess.STDOUT, stdout=subprocess.PIPE, close_fds=True).communicate()[0]
identity = re.search('Authority=(.*)', signing_info).group(1)
subprocess.call(['codesign', '--sign', identity, '--force', '--preserve-metadata=entitlements,resource-rules,requirements', '/Users/stefanfisk/Projekt/Tunaspot/Xamarin/App/Touch/bin/iPhone/Ad-Hoc/Touch.app'])