Re: mail signing history, was Call for Community Feedback: Retiring IETF FTP Service

[Michael Thomas <[e-mail]>]

On 11/18/20 2:29 PM, Stephen Farrell wrote:
>
>
>>> Publishing the private key enables various forms of
>>> denyability - if someone claims msg1 is original
>>> anyone with access to the private can produce a
>>> msg2 that seems as cryptographically correct but
>>> is clearly bogus (e.g. containing lottery numbers
>>> that post-date message timestamps).
>>
>>
>> Yes, i acknowledge that above albeit obliquely. What i don't see is 
>> how you align providers goals' with individual users' goals.
>
> My guess is that email service providers that are
> concerned about potential leakage of message store
> content would be motivated to do this so as to
> re-assure their users and/or maybe help avoid future
> liability (financial or moral).

It would be pretty disasterous regardless of a valid DKIM signature. 
Most people have no clue that email *also* prevents deniability but  the 
damage would already be done because nobody's going believe that 
somebody's long cheating email romance was just elaborately spoofed. 
Same goes for providers if they screw up: an invalidated DKIM signature 
is not going to protect them from lawsuits.

MIke