From: Andreas Dilger <adilger@dilger.ca>
To: Richard Weinberger <richard@nod.at>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Theodore Ts'o" <tytso@mit.edu>,
Eric Biggers <ebiggers@google.com>,
David Gstir <david@sigma-star.at>
Subject: Re: Question on ext4 directory hashes in combination with file name encryption
Date: Fri, 30 Sep 2016 14:20:00 -0600 [thread overview]
Message-ID: <CAF99CF6-E26D-4696-9F12-B3DFBC3C7561@dilger.ca> (raw)
In-Reply-To: <9a5198b3-0c00-a558-5132-9c38b4bb8795@nod.at>
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On Sep 30, 2016, at 8:09 AM, Richard Weinberger <richard@nod.at> 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
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next prev parent reply other threads:[~2016-09-30 20:20 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-30 14:09 Richard Weinberger
2016-09-30 20:20 ` Andreas Dilger [this message]
2016-09-30 22:05 ` Theodore Ts'o
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