Re: [TLS] Reducing record expansion overhead allowance

["StJohns, Michael" <[e-mail]>]

You mean as part of the plain text?

On Sunday, July 20, 2014, Eric Rescorla <[e-mail]> wrote:

> On Sun, Jul 20, 2014 at 7:52 AM, StJohns, Michael <[e-mail]
> <javascript:_e(%7B%7D,'cvml','[e-mail]');>> wrote:
>
>> The only other thing that hasn't been mentioned that was discussed at the
>> interim in Denver is padding for traffic analysis resistance. That could
>> hit 1k in size.  But since there's no proposal that's just a guess on size.
>>
>
>
> I believe the consensus here was to have padding be done separately.
>
> -Ekr
>
>
>>
>> On Saturday, July 19, 2014, Eric Rescorla <[e-mail]
>> <javascript:_e(%7B%7D,'cvml','[e-mail]');>> wrote:
>>
>>>  https://github.com/tlswg/tls13-spec/issues/55
>>>
>>> In TLS 1.2, we had the following maximum values:
>>>
>>> TLSPlaintext: 2^{14}
>>> TLSCompressed: 2^{14} + 1024
>>> TLSCiphertext: 2^{14} + 2048
>>>
>>> These overhead values allow for expansion in these transforms
>>> due to potential bad compression overhead or padding, etc.
>>>
>>> Wan-Teh Chang points out that we no longer have compression
>>> so there's no need to allow for 1024 bytes of expansion there.
>>>
>>> Minimally we should reduce the TLSCiphertext overhead to
>>> 2^{14} + 1024. Do people believe that we will have AEAD
>>> ciphers with 1024 bytes of expansion or should we reduce
>>> it further? I'm inclined to not re-judge that and just leave it
>>> at 2^{14} + 1024.
>>>
>>> Thoughts?
>>> -Ekr
>>>
>>>
>