Re: [TLS] DHE key derivation

Michael D'Errico <mike-list@pobox.com> Fri, 27 September 2013 16:19 UTC

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Date: Fri, 27 Sep 2013 09:19:03 -0700
From: Michael D'Errico <mike-list@pobox.com>
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Subject: Re: [TLS] DHE key derivation
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Martin Rex wrote:
>> It is not recommended to use the same RSA key for both signing and
>> key encipherment.
> 
> Isn't that (using the same RSA key for both signing and key encipherment)
> what pretty much all TLS Servers do when they support both,
> traditional RSA ciphersuites plus DHE_RSA and/or ECDHE_RSA?

I believe that many servers do use the same key for both, though
they don't have to.  This practice is likely due to cost (buy one
certificate instead of two) and software limitations.

Mike