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Re: [PATCH v2 6/9] staging: ccree: add FIPS support

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Am Montag, 24. April 2017, 08:06:09 CEST schrieb Gilad Ben-Yossef:

Hi Gilad,
> 
> Well, it turns out there is and we do :-)
> 
> This is from crypto/des_generic.c:
> 
> /*
>  * RFC2451:
>  *
>  *   For DES-EDE3, there is no known need to reject weak or
>  *   complementation keys.  Any weakness is obviated by the use of
>  *   multiple keys.
>  *
>  *   However, if the first two or last two independent 64-bit keys are
>  *   equal (k1 == k2 or k2 == k3), then the DES3 operation is simply the
>  *   same as DES.  Implementers MUST reject keys that exhibit this
>  *   property.
>  *
>  */
> int __des3_ede_setkey(u32 *expkey, u32 *flags, const u8 *key,
>                       unsigned int keylen)
> 
> However, this does not check that k1 == k3. In this case DES3
> becomes 2DES (2-keys TDEA), the use of which was dropped post 2015
> by NIST Special Publication 800-131A*.

It is correct that the RFC wants at least a 2key 3DES. And it is correct that 
SP800-131A mandates 3key 3DES post 2015. All I am saying is that FIPS 140-2 
does *not* require a technical verification of the 3 keys being not identical.

Note, formally, FIPS 140-2 requires that the 3 keys (i.e. all 192 bits) must 
be obtained from *one* call to a DRBG or KDF (separate independent calls to, 
say, obtain one key at a time is *not* permitted). Of course, fixing the 
parity bits is allowed after obtaining the random number.
> 
> Would it be acceptable if I offer a patch adding this check to
> __des3_ede_setkey()
> and use that in the ccree driver?

I am not sure it makes sense as the core requirement is the *one* invocation 
of the DRBG.

Ciao
Stephan

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[PATCH v2 0/9] staging: ccree: add Arm TrustZone CryptoCell REE driver Gilad Ben-Yossef <gilad@benyossef.com> - 2017-04-20 15:20 +0200
  Re: [PATCH v2 1/9] staging: ccree: introduce CryptoCell HW driver Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-20 15:40 +0200
    Re: [PATCH v2 1/9] staging: ccree: introduce CryptoCell HW driver Gilad Ben-Yossef <gilad@benyossef.com> - 2017-04-20 15:50 +0200
      Re: [PATCH v2 1/9] staging: ccree: introduce CryptoCell HW driver Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-20 16:10 +0200
        Re: [PATCH v2 1/9] staging: ccree: introduce CryptoCell HW driver Gilad Ben-Yossef <gilad@benyossef.com> - 2017-04-23 11:40 +0200
  Re: [PATCH v2 0/9] staging: ccree: add Arm TrustZone CryptoCell REE  driver Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-20 15:40 +0200
    Re: [PATCH v2 0/9] staging: ccree: add Arm TrustZone CryptoCell REE driver Gilad Ben-Yossef <gilad@benyossef.com> - 2017-04-20 15:40 +0200
  Re: [PATCH v2 6/9] staging: ccree: add FIPS support Stephan Müller <smueller@chronox.de> - 2017-04-20 15:50 +0200
    Re: [PATCH v2 6/9] staging: ccree: add FIPS support Gilad Ben-Yossef <gilad@benyossef.com> - 2017-04-23 11:50 +0200
      Re: [PATCH v2 6/9] staging: ccree: add FIPS support Stephan Müller <smueller@chronox.de> - 2017-04-23 21:00 +0200
      Re: [PATCH v2 6/9] staging: ccree: add FIPS support Gilad Ben-Yossef <gilad@benyossef.com> - 2017-04-24 08:10 +0200
        Re: [PATCH v2 6/9] staging: ccree: add FIPS support Stephan Müller <smueller@chronox.de> - 2017-04-24 08:20 +0200
          Re: [PATCH v2 6/9] staging: ccree: add FIPS support Stephan Müller <smueller@chronox.de> - 2017-04-24 08:30 +0200
            Re: [PATCH v2 6/9] staging: ccree: add FIPS support Gilad Ben-Yossef <gilad@benyossef.com> - 2017-04-24 09:10 +0200
              Re: [PATCH v2 6/9] staging: ccree: add FIPS support Stephan Müller <smueller@chronox.de> - 2017-04-24 09:30 +0200
          Re: [PATCH v2 6/9] staging: ccree: add FIPS support Gilad Ben-Yossef <gilad@benyossef.com> - 2017-04-24 09:10 +0200
            Re: [PATCH v2 6/9] staging: ccree: add FIPS support Stephan Müller <smueller@chronox.de> - 2017-04-24 09:30 +0200

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