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Re: [Dcrup] I do not like the dcrup ECC document

Brandon Long <blong@google.com> Mon, 10 July 2017 23:08 UTC

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From: Brandon Long <blong@google.com>
Date: Mon, 10 Jul 2017 16:08:23 -0700
Message-ID: <CABa8R6vVSg0H2ArWj8Y9NVyyKFgdvGD+61rfHdtkaXyeq3CWqQ@mail.gmail.com>
To: "Murray S. Kucherawy" <superuser@gmail.com>
Cc: John R Levine <johnl@taugh.com>, dcrup@ietf.org, Russ Housley <housley@vigilsec.com>
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Subject: Re: [Dcrup] I do not like the dcrup ECC document
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On Sun, Jul 9, 2017 at 11:50 PM, Murray S. Kucherawy <superuser@gmail.com>
wrote:

> On Sun, Jul 9, 2017 at 2:14 PM, John R Levine <johnl@taugh.com> wrote:
>
>> RFC 6376 describes in great detail in section 3.7 how to create the
>> material to be signed.  What it ends up with is a sha-256 hash, but that's
>> not the signing algorithm's problem.  I say PureEdDSA to emphasize that it
>> doesn't get hashed again.
>>
>> As it stands now, the RSA and EdDSA signing algorithms sign the same
>> thing.  I suppose I could extensively rewrite the signing instructions so
>> that stuff to be signed by RSA is hashed while stuff to be signed by EdDSA
>> is not because it'll use HashEdDSA, but that seems a lot of work and a lot
>> of code changes for no benefit.
>>
>
> +1, unless there is such benefit and someone could describe it (or point
> us to a reference that does so).
>

Is there any cryptographic reason why doing this is worse?

Brandon

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