_krb5_derive_key
ret = _krb5_derive_key(context, et, &d, constant, constant_len);
_krb5_derive_key(context, crypto->et, d, constant, sizeof(constant));
_krb5_derive_key (
ret = _krb5_derive_key(context, et, &kd, "kerberos", strlen("kerberos"));
ret = _krb5_derive_key(context,