Re: [Cfrg] Encrypt in place guidance

[Robert Moskowitz <[e-mail]>]

On 3/31/20 9:10 PM, Blumenthal, Uri - 0553 - MITLL wrote:
>
> I will write the draft using Speck for 64 bit block.  That will get 
> the draft out and open up for discussion.
>
> You’d probably write a draft requiring a 64-bit block cipher, 
> proposing SPECK as one that fits the requirements, both 
> block-size-wise and key-size-wise.
>

I am wordsmithing this now.  Of course the draft COULD go in tomorrow, 
but then it would be dated Apr 1.  So I will probably wait until Thrusday...

> And if I had a 2 byte IV, I could get AES-CTR working to protect 
> 2^16-1 messages.  More than enough for a mission.
>
> In fact, if you have two bytes for crypto expansion – you could do 
> better than CTR.
>

I am updating my draft with this approach right now.  I figured it out 
myself.  I am so proud of me.  ;)

> This will be up to ASTM and the regulators with us advising.
>
> I don’t even know what ASTM is. ;-)
>

astm.org

The standard for UAS Remote ID and Tracking is F3411-19 and is not only 
referenced by the FAA but also EASA.  It costs $85 to purchase or get 
your ASTM membership for $75.

> Simon and speck are controversial, and almost nobody believed that 
> they weren’t deliberately crippled.  It hasn’t been proven.  But there 
> were enough concerns that ISO rejected them.  See 
> https://rwc.iacr.org/2019/slides/RWC87slides.pdf
>
> Count me among those “almost”.
>
> Also, I wasn’t much impressed by those slides.
>
> I mention all this because I am sure using Speck will be 
> controversial, and you need to be sure that you are willing to take on 
> that battle.
>
> Depends on the customer. I’m sure FAA, DOT, or other US govt entity 
> would have no problem with SPECK.
>

But maybe not EASA (not entirely sure EASA is the 'correct' EU agency).  
The two together very much control the world-wide decision process.  Of 
course New Zealand could weigh in.  They manage ~1/6 of the world's 
airspace.