Re: [Uta] comments on draft-ietf-uta-tls-for-email-00.txt

[Keith Moore <[e-mail]>]

I knew I forgot something:

4. I think it would be appropriate for the title of this document to be 
something that relates it to RFC 8314, for example:

Updates to Use of Transport Layer Security (TLS) for Email Submission 
and Access

The current title reads as if this document were the main body of 
recommendations.

Keith

On 11/27/18 9:35 PM, Keith Moore wrote:
> 1. I especially appreciate this document being expressed as deltas to 
> RFC 8314, as I believe this makes it much easier for a reader 
> (especially an implementor or mail service operator) to understand 
> exactly what's being changed.
>
> 2.  For existing accounts that have already been established between 
> an MUA and a mail service, should updated MUAs that follow these 
> revised recommendations continue to regard TLS 1.1 as providing the 
> minimum confidentiality level?    Or should such MUAs now warn users 
> that these services no longer provide adequate confidentiality?   Or 
> are there specific server profiles (e.g. certain ciphersuites) of TLS 
> 1.1 that still provide adequate confidentiality which can be detected 
> by the client?
>
> IMO there is a delicate compromise to be made between:
>
> - encouraging service operators to upgrade their security,
>
> - not encouraging users to worry needlessly about security risks that 
> don't actually exist, and especially,
>
> - not conditioning users to ignore security warnings because they're 
> too frequently present.
>
> So when an updated MUA uses an existing account configuration to make 
> a connection with a server that supports TLS 1.1 at most, IMO it 
> should still regard that connection as providing minimum 
> confidentiality as long as there's no reason to believe that the 
> connection is insecure.  (Updated MUAs will still flag newly 
> established connection to that server as not having minimum 
> confidentiality, so operators still have some incentive to .)
>
> However if the TLS 1.1 connection (for example) is using a ciphersuite 
> now known to be insecure, an updated MUA should begin to flag those 
> connections as no longer having minimum confidentiality.
>
> (The theory that I have is that if security warnings to users are 
> consistently accurate and provide a warning of severity that is 
> proportionate to the threat, users will learn to treat them as credible.)
>
> Keith
>
>
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