Re: [PATCH 0/6] Constant Time Memory Comparisons Are Important

From	Emmanuel Grumbach <egrumbach@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 0/6] Constant Time Memory Comparisons Are Important
Date	2017-06-11 22:50 +0200
Message-ID	<tRhY5-1cV-3@gated-at.bofh.it> (permalink)
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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.

Thread

[PATCH 0/6] Constant Time Memory Comparisons Are Important "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-10 05:00 +0200
  [PATCH 3/6] ccree: use constant time memory comparison for macs and tags "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-10 05:00 +0200
    Re: [PATCH 3/6] ccree: use constant time memory comparison for macs  and tags Gilad Ben-Yossef <gilad@benyossef.com> - 2017-06-10 09:50 +0200
      Re: [PATCH 3/6] ccree: use constant time memory comparison for macs  and tags "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-10 13:00 +0200
        Re: [PATCH 3/6] ccree: use constant time memory comparison for macs  and tags Henrique de Moraes Holschuh <hmh@hmh.eng.br> - 2017-06-10 23:50 +0200
  [PATCH 2/6] net/ipv6: use constant time memory comparison for mac "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-10 05:10 +0200
  [PATCH 4/6] security/keys: use constant time memory comparison for macs "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-10 05:10 +0200
    Re: [kernel-hardening] [PATCH 4/6] security/keys: use constant time  memory comparison for macs James Morris <jmorris@namei.org> - 2017-06-14 11:00 +0200
  [PATCH 1/6] sunrpc: use constant time memory comparison for mac "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-10 05:10 +0200
  [PATCH 5/6] bluetooth/smp: use constant time memory comparison for secret values "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-10 05:10 +0200
    Re: [PATCH 5/6] bluetooth/smp: use constant time memory comparison  for secret values Marcel Holtmann <marcel@holtmann.org> - 2017-06-10 15:50 +0200
  [PATCH 6/6] mac80211/wpa: use constant time memory comparison for MACs "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-10 05:10 +0200
    Re: [PATCH 6/6] mac80211/wpa: use constant time memory comparison  for MACs Johannes Berg <johannes@sipsolutions.net> - 2017-06-13 10:30 +0200
      Re: [PATCH 6/6] mac80211/wpa: use constant time memory comparison for MACs "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-13 15:30 +0200
  Re: [PATCH 0/6] Constant Time Memory Comparisons Are Important Kalle Valo <kvalo@codeaurora.org> - 2017-06-11 10:20 +0200
    Re: [PATCH 0/6] Constant Time Memory Comparisons Are Important Kees Cook <keescook@chromium.org> - 2017-06-11 15:40 +0200
      Re: [PATCH 0/6] Constant Time Memory Comparisons Are Important Emmanuel Grumbach <egrumbach@gmail.com> - 2017-06-11 22:50 +0200
        Re: [PATCH 0/6] Constant Time Memory Comparisons Are Important Emil Lenngren <emil.lenngren@gmail.com> - 2017-06-11 23:40 +0200
          Re: [PATCH 0/6] Constant Time Memory Comparisons Are Important Emmanuel Grumbach <egrumbach@gmail.com> - 2017-06-12 07:10 +0200
          Re: [PATCH 0/6] Constant Time Memory Comparisons Are Important Arend van Spriel <arend.vanspriel@broadcom.com> - 2017-06-12 09:40 +0200
  Re: [PATCH 0/6] Constant Time Memory Comparisons Are Important Stephan Müller <smueller@chronox.de> - 2017-06-11 23:10 +0200
    Re: [PATCH 0/6] Constant Time Memory Comparisons Are Important "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-11 23:30 +0200
  [PATCH] rsa-pkcs1pad: use constant time memory comparison for MACs "Jason A. Donenfeld" <Jason@zx2c4.com> - 2017-06-11 23:30 +0200

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