Re: [TLS] draft-ietf-tls-session-hash-04 and session resumption

I guess my question is whether “SHOULD perform a full handshake” is strong enough,
leaving the server the option of aborting the handshake, or is MUST preferable
as a clearer indication to implementers?

On 15 Apr 2015, at 08:15, Karthikeyan Bhargavan <karthik.bhargavan@gmail.com> wrote:

> I like Martin’s text, and have edited it to the following:
> 
>    If the original session did not use an extended master secret but
>    the new ClientHello does contain the "extended_master_secret"
>    extension, the server MUST NOT continue the abbreviated handshake.
>    Instead, it SHOULD perform a full handshake to negotiate a new session.
> 
> If this looks acceptable, I’ll put out a new version of the draft today.
> 
> -K.
> 
> On 15 Apr 2015, at 03:53, Martin Rex <mrex@sap.com> wrote:
> 
>> Karthikeyan Bhargavan wrote:
>>> How about the following:
>>>     If the original session did not use an extended master secret but
>>>     the new ClientHello does contain the "extended_master_secret"
>>>     extension, the server MUST fall back to a full handshake by
>>>     sending a ServerHello that rejects session resumption and offers a
>>>     new session.
>> 
>> Too complicated for my taste.  I do not see a need for words like
>> fallback and reject, and these actually do not exist in the TLS protocol.
>> 
>> 
>>    If the original session did not use an extended master secret but
>>    the new ClientHello does contain the "extended_master_secret"
>>    extension, the server MUST perform a full handshake to negotiate
>>    a new session (i.e. the server MUST NOT perform an abbreviated
>>    handshake aka session resume).
>> 
>> 
>> -Martin
> 
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