Re: I have a technical idea/change for the ECC draft

[Greg Troxel <gdt@xxxxxxxxxx>]

"David Crick" <dacrick@xxxxxxxxx> writes:

>> What do we loose if we
>> instead use "this key replaces TrippleDES implicit algorithm with AES-128"
>> notation? This would be beneficial for RSA keys too.
>
> what if we have:
>
> Alice: {AES256, AES128, AESover3DESflag [, 3DES implicitly]}
> Bob: {3DES [, AES128 implicitly]}
>
> Then Bob or his software could legitamately choose 3DES.
>
> whereas:
>
> Alice: ECC-384/521 key with {AES256, SuiteBOnly}  and
> Alice: ECC-256 key with { [AES128 implicit], SuiteBOnly}
>
> would refuse to encrypt with anything except AES256 and
> AES128 respectively.

I think there's a fundamental mismatch between OpenPGP-style key
preferences and Suite B thinking.  As a sender, with labeled
information, you can only use approved algorithms.  Thus, if a recipient
doesn't list the approved algorithm, you just can't send them mail.  The
OpenPGP-style key preferences are in my view primarily to ensure
interoperability and allow for algorithm transitions over long
timescales.

Are we proposing sender-side rules to match labels to approved
algorithms?  It seems inadequate to put 'SuiteBOnly' as a key preference
on recipients.