Re: [TLS] MTI kx groups, HelloRetryRequest and "Incorrect DHE Share"

2016-12-27 Thread Eric Rescorla
On Tue, Dec 27, 2016 at 7:06 PM, David Benjamin wrote: > On Tue, Dec 27, 2016 at 4:44 PM Joseph Birr-Pixton > wrote: > > Hi folks, > > It appears to me that HRR is a pretty large and tricky source of > complexity in TLS1.3. Judging by the implementations page, 40% don't > support it right now. I

Re: [TLS] MTI kx groups, HelloRetryRequest and "Incorrect DHE Share"

2016-12-27 Thread david wong
HRR is a pretty simple message to implemement. Including it into a ServerHello would complexify the protocol without much gain imo. I also think that forcing a client to use one of the curve is not a good idea either. Who is going to agree on what curve it should be here :) ? Probably browser

Re: [TLS] MTI kx groups, HelloRetryRequest and "Incorrect DHE Share"

2016-12-27 Thread David Benjamin
On Tue, Dec 27, 2016 at 4:44 PM Joseph Birr-Pixton wrote: Hi folks, It appears to me that HRR is a pretty large and tricky source of complexity in TLS1.3. Judging by the implementations page, 40% don't support it right now. It's *precisely the kind of thing* that vendors could easily ship broken

Re: [TLS] MTI kx groups, HelloRetryRequest and "Incorrect DHE Share"

2016-12-27 Thread Eric Rescorla
On Tue, Dec 27, 2016 at 2:27 PM, Xiaoyin Liu wrote: > Hi Joe, > > > > My understanding is that we can't get rid of HRR unless we require clients > to send a key_share for every key exchange group in the supported_groups > extension. This would be a quite large overhead if the client wants to > su

Re: [TLS] MTI kx groups, HelloRetryRequest and "Incorrect DHE Share"

2016-12-27 Thread Xiaoyin Liu
Hi Joe, My understanding is that we can't get rid of HRR unless we require clients to send a key_share for every key exchange group in the supported_groups extension. This would be a quite large overhead if the client wants to support lots of groups. Also HRR allows servers to request clie

[TLS] MTI kx groups, HelloRetryRequest and "Incorrect DHE Share"

2016-12-27 Thread Joseph Birr-Pixton
Hi folks, It appears to me that HRR is a pretty large and tricky source of complexity in TLS1.3. Judging by the implementations page, 40% don't support it right now. It's *precisely the kind of thing* that vendors could easily ship broken/missing support for, and they'd get away with it for years