http://3cbzkrvakrpetjjppdwzbzqrlkmzatjs7jbyazap5gwutj32gcltjpqd.onion
So we impose a new symmetry: Whenever we introduce new bits (bits that were
previously always set), they need to start from the right. So now this start
of a sequence is valid: 00011
00101 but this is not: 00011
01001 The reason is, again, that we could get the first sequence from the second
by flipping the second and third bit (counting from the left).