Re: [TLS] Issue #964: Shortened HKDF labels

[Benjamin Kaduk <[e-mail]>]

On 04/24/2017 03:57 PM, Dave Garrett wrote:
>> If people feel like we should have some "TLS" prefix, I think "TLS " would
>> be enough, giving us 1 bytes.
> (assuming you mean 14 bytes here)
>
> If I remember correctly, in some discussion quite a while back, we decided we wanted to bake the version number into the labels. This could be done more compactly by adding a ProtocolVersion value (2 bytes) to the HkdfLabel struct. 


I would prefer to keep both "TLS" and the version number involved.  I
generally don't mind having a non-ASCII encoding for the version number,
but then we have to pay attention to avoid putting a NULL byte in it by
accident.

-Ben

> "TLS" could be stuck in there as a static 3 byte opaque string, with no length or space. (yeah, the combined plaintext will go "TLSclient hs traffic", but nobody needs to care)