_krb5_xor
_krb5_xor(k, (const unsigned char*)"\0\0\0\0\0\0\0\xf0");
_krb5_xor(&k[i], (const unsigned char*)"\0\0\0\0\0\0\0\xf0");
_krb5_xor (
_krb5_xor(keys + i, (const unsigned char*)"\0\0\0\0\0\0\0\xf0");
_krb5_xor(keys + i, (const unsigned char*)"\0\0\0\0\0\0\0\xf0");