Re: [RFC][PATCH] ensure i_ino uniqueness in filesystems without permanent inode numbers (via pointer conversion)

[Jeff Layton <jlayton@redhat.com>]

On Fri, 2006-11-17 at 07:24 -0700, Matthew Wilcox wrote:
> I *think* the xor mask is mere obfuscation.  It looks likely that you can
> recover it with a little bit of trial and error.  If you can force the
> filesystem to hand you back new inodes quickly such that there is a high
> probability you get consecutive allocations, you'll get a sequence which
> would be spaced 700-odd bytes apart, except that it's been xored.  Since
> you know it's incrementing, if you see the sequence decrease, you'll
> know that was a 1 in that bit.

I think you're right, the addresses would often be sequential, so this
is probably crackable. I'll look over the md5 routines when I get the
chance, though if someone more cryptographically inclined than I has a
different suggestion, I'd love to hear it.
-- Jeff