def getSessionTypes(assoc_type):
    """Return the allowed session types for a given association type"""
    assoc_to_session = {
        'HMAC-SHA1': ['DH-SHA1', 'no-encryption'],
        'HMAC-SHA256': ['DH-SHA256', 'no-encryption'],
        }
    return assoc_to_session.get(assoc_type, [])