[krbdev.mit.edu #1278] No prompter interface for krb5_get_init_creds_keytab

[Ken Hornstein via RT]

I discovered recently that the API krb5_get_init_creds_keytab doesn't
take a prompter argument.  This makes it difficult to do things like
hardware preauthentication using a key stored in a keytab.

I propose the following API to solve the problem:

krb5_get_init_creds_keytab_prompter
KRB5_PROTOTYPE((krb5_context context,
                krb5_creds *creds,
                krb5_principal client,
                krb5_keytab arg_keytab,
                krb5_prompter_fct prompter,
                void *data,
                krb5_deltat start_time,
                char *in_tkt_service,
                krb5_get_init_creds_opt *options));

(Obviously, it looks a whole lot like the krb5_get_init_creds_keytab
API).  I'm not so convinced the name is particularly great, though.

Any comments?