From: Emmanuel Grumbach <egrumbach@gmail.com>
To: Emil Lenngren <emil.lenngren@gmail.com>
Cc: Kees Cook <keescook@chromium.org>,
Kalle Valo <kvalo@codeaurora.org>,
"Jason A. Donenfeld" <Jason@zx2c4.com>,
LKML <linux-kernel@vger.kernel.org>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Anna Schumaker <anna.schumaker@netapp.com>,
David Howells <dhowells@redhat.com>,
David Safford <safford@us.ibm.com>,
"David S. Miller" <davem@davemloft.net>,
Gilad Ben-Yossef <gilad@benyossef.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Gustavo Padovan <gustavo@padovan.org>,
"J. Bruce Fields" <bfields@fieldses.org>,
Jeff Layton <jlayton@poochiereds.net>,
Johan Hedberg <johan.hedberg@gmail.com>,
Johannes Berg <johannes@sipsolutions.net>,
Marcel Holtmann <marcel@holtmann.org>,
Mimi Zohar <zohar@linux.vnet.ibm.com>,
Trond Myklebust <trond.myklebust@primarydata.com>,
keyrings@vger.kernel.org,
Bluez mailing list <linux-bluetooth@vger.kernel.org>,
"open list:NFS, SUNRPC, AND..." <linux-nfs@vger.kernel.org>,
linux-wireless <linux-wireless@vger.kernel.org>,
Network Development <netdev@vger.kernel.org>
Subject: Re: [PATCH 0/6] Constant Time Memory Comparisons Are Important
Date: Mon, 12 Jun 2017 08:03:33 +0300 [thread overview]
Message-ID: <CANUX_P1n0=rK+biS7M0-vxP5Uhk5rU+qj4_9jtdRF9Yh219PVA@mail.gmail.com> (raw)
In-Reply-To: <CAO1O6see6yDr-hDVNPi9Kv9wO6p-98w7YhsnnwnVOVCSEGVksw@mail.gmail.com>
On Mon, Jun 12, 2017 at 12:30 AM, Emil Lenngren <emil.lenngren@gmail.com> wrote:
> 2017-06-11 22:48 GMT+02:00 Emmanuel Grumbach <egrumbach@gmail.com>:
>> On Sun, Jun 11, 2017 at 4:36 PM, Kees Cook <keescook@chromium.org> wrote:
>>>
>>> On Sun, Jun 11, 2017 at 1:13 AM, Kalle Valo <kvalo@codeaurora.org> wrote:
>>> > "Jason A. Donenfeld" <Jason@zx2c4.com> writes:
>>> >
>>> >> Whenever you're comparing two MACs, it's important to do this using
>>> >> crypto_memneq instead of memcmp. With memcmp, you leak timing information,
>>> >> which could then be used to iteratively forge a MAC.
>>> >
>>> > Do you have any pointers where I could learn more about this?
>>>
>>> While not using C specifically, this talks about the problem generally:
>>> https://www.chosenplaintext.ca/articles/beginners-guide-constant-time-cryptography.html
>>>
>>
>> Sorry for the stupid question, but the MAC address is in plaintext in
>> the air anyway or easily accessible via user space tools. I fail to
>> see what it is so secret about a MAC address in that code where that
>> same MAC address is accessible via myriads of ways.
>
> I think you're mixing up Media Access Control (MAC) addresses with
> Message Authentication Code (MAC). The second one is a cryptographic
> signature of a message.
Obviously... Sorry for the noise.
next prev parent reply other threads:[~2017-06-12 5:03 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-10 2:59 [PATCH 0/6] Constant Time Memory Comparisons Are Important Jason A. Donenfeld
2017-06-10 2:59 ` [PATCH 1/6] sunrpc: use constant time memory comparison for mac Jason A. Donenfeld
2017-06-11 8:13 ` [PATCH 0/6] Constant Time Memory Comparisons Are Important Kalle Valo
2017-06-11 13:36 ` Kees Cook
2017-06-11 20:48 ` Emmanuel Grumbach
2017-06-11 21:30 ` Emil Lenngren
2017-06-12 5:03 ` Emmanuel Grumbach [this message]
2017-06-12 7:33 ` Arend van Spriel
2017-06-11 21:06 ` Stephan Müller
2017-06-11 21:21 ` Jason A. Donenfeld
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