From: "Theodore Ts'o" <tytso@mit.edu>
To: Richard Weinberger <richard@nod.at>
Cc: linux-ext4@vger.kernel.org,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
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 18:05:33 -0400 [thread overview]
Message-ID: <20160930220533.x4cbv2g2ynsetqhn@thunk.org> (raw)
In-Reply-To: <9a5198b3-0c00-a558-5132-9c38b4bb8795@nod.at>
On Fri, Sep 30, 2016 at 04:09:09PM +0200, Richard Weinberger wrote:
>
> if I read the ext4 code correctly, you pass encrypted filenames to ext4fs_dirhash().
> These filenames are not encoded and therefore binary gibberish.
That's correct.
> 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.
I'm not particularly worried. In general, while the converse is true;
that hashes that assume that they are used for binary data might not
work as well for ASCII strings, the ext4 hash functions should work
fine for binary data.
- Ted
prev parent reply other threads:[~2016-10-01 0:44 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
2016-09-30 22:05 ` Theodore Ts'o [this message]
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