Re: Question on ext4 directory hashes in combination with file name encryption

[Andreas Dilger]

On Sep 30, 2016, at 8:09 AM, Richard Weinberger <richard@xxxxxx> wrote:
> 
> Hi,
> 
> if I read the ext4 code correctly, you pass encrypted filenames to ext4fs_dirhash().
> These filenames are not encoded and therefore binary gibberish.
> Isn't this a problem for the ext4 hash functions? My fear is that these hashes are optimized
> for ASCII strings and produce more collisions when binary data is used as input.

The default hash function (half-md4) is an (old) crypto hash and works
fine with binary data.  Some of the other hash functions are less strong,
but I don't think anyone changes the hash function for ext4.

Cheers, Andreas

Attachment: signature.asc
Description: Message signed with OpenPGP using GPGMail