auth algo XOR

enum osmo_auth_algo features OSMO_AUTH_ALG_XOR, but now that I'm trying to use it, I notice that we have no code actually implementing OSMO_AUTH_ALG_XOR. We have xor as algorithm exposed as a VTY option in the osmo-hlr DB, but when I choose it, I must notice that libosmocore doesn't osmo_auth_register() any xor implementation. Another detail is that I happen to remember that XOR is set as algorithm on the SIM cards we have in the osmo-gsm-tester, at least in the RnD unit. How should we deal with it? Implement xor, or remove it from osmo-hlr? Or am I missing something? ~N