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Reply-To: Brian DOT Inglis AT SystematicSw DOT ab DOT ca
Subject: Re: Question regarding OpenSSL 1.1.1b package configuration against OpenSSL 1.0.2r
To: cygwin AT cygwin DOT com
References: <CABTpe59pFoH-MsGKKa4oNdFTs42opV64motaSFpeijJCq0Dqcw AT mail DOT gmail DOT com>
From: Brian Inglis <Brian DOT Inglis AT SystematicSw DOT ab DOT ca>
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Date: Mon, 3 Jun 2019 14:35:29 -0600
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On 2019-06-03 06:09, Benjamin Baratte wrote:
> I would like to understand why the OpenSSL 1.1.1b package only includes the
> NIST EC curves support ?
> I'm basically try to use brainpool curves and I have noticed that the
> package 1.1.1b does not includes these curves and more generally only
> includes NIST curves

> From what I have found in Google, the cygwin OpenSSL 1.1.1b package is
> bound to the fedora package spec which is deactivating brainpool curves.
> 
> I'm a bit surprised by the differences in the 2 OpenSSL packages. But I
> need to use Brainpool curves.
> 
> On top of that, the installer is proposing the OpenSSL 1.1.1b-1 package as
> the newest one prevailing to OpenSSL 1.0.2r-1 package. Is it possible to
> get back the brainpool curves into the OpenSSL 1.1.1b-1 package ?
> if not, could please explain to me why only NIST curves are now supported
> in the official package ?

I have seen comments about legal liability, poor performance limited by choice
of random keys, small size of random keys, another model specific Intel FP bug:

https://github.com/openssl/openssl/blob/master/CHANGES
"Montgomery multiplication may produce incorrect results

     There is a carry propagating bug in the Broadwell-specific Montgomery
     multiplication procedure that handles input lengths divisible by, but
     longer than 256 bits. ... Otherwise the bug can manifest itself as
     transient authentication and key negotiation failures or reproducible
     erroneous outcome of public-key operations with specially crafted input.
     Among EC algorithms only Brainpool P-512 curves are affected and one
     presumably can attack ECDH key negotiation. ...

     This issue was publicly reported as transient failures and was not
     initially recognized as a security issue. Thanks to Richard Morgan for
     providing reproducible case.
     (CVE-2016-7055)
     [Andy Polyakov]"

You can easily rebuild the package yourself with the cygport utility, to check
that works, then change the build config to include the Brainpool ECs, and
rebuild the way you want it.

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

This email may be disturbing to some readers as it contains
too much technical detail. Reader discretion is advised.

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