OSStatus status = errSecSuccess;
CFTypeRef  persistent_ref = NULL;
const void *keys[] =   { kSecReturnPersistentRef, kSecValueRef };
const void *values[] = { kCFBooleanTrue,          identity };
CFDictionaryRef dict = CFDictionaryCreate(NULL, keys, values,
                                                2, NULL, NULL);
status = SecItemAdd(dict, &persistent_ref);
if (dict)
   CFRelease(dict);
return (CFDataRef)persistent_ref;