[cabfpub] Proposal for modified Google SHA-1 deprecation policy

kirk_hall at trendmicro.com kirk_hall at trendmicro.com
Thu Aug 28 19:04:24 MST 2014

Ryan and Chris – here is a serious proposal for a modified Google SHA-1 policy.  It meets all of your stated goals.  Please give it some consideration.

1.  SHA-1 certs issued on or after [Nov. 1, 2014] that expire on or after January 1, 2017 get a double whammy bad UI in Google upon issuance – red slash and nasty click-throughs.  (This will stop issuance of 2017 SHA-1 certs this fall.)

2.  SHA-1 certs issued before [Nov. 1, 2014] that expire on or after January 1, 2017 get a double whammy bad UI in Google starting [March 1, 2015] – red slash only and nasty click-throughs.   (This will force existing websites with 2017 SHA-1 certs to change them within the next six months).

Result: All 2017 SHA-1 certs will be gone by next March 2015 – which certainly meets your goals.  Customers with existing 2017 certs can get through this holiday season, CAs can get the message out.


1.  CAs that have never issued 2017 certs, and never will (like Trend Micro) and their customers are not affected – that’s appropriate, as we have never been a part of this problem.

2.  CAs that have issued three year SHA-1 certs expiring in 2017 will stop by this fall.

3.  CAs that have issued 2017 certs in the past (and their customers) will be affected, but will have six months to adjust.  That will be a much smaller number of customers affected than if those with 2016 certs are forced to change their certs twice (in 2014 and again in 2015).

4.  All SHA-1 certs will likely be gone by next spring.

I don’t think Google should spend much time worrying about how CAs communicate with their customers about the need to move to SHA-256 before 2017 – that’s for us to worry about, and we are all strongly incentivized to get the message out (selling a 2017 cert that doesn’t work creates legal problems, and none of us wants to be dealing with angry SHA-1 customers in late 2016 who have to switch to SHA-256).  We may also be able to get behind Google’s policy if it is revised – something that isn’t the case today.

You mentioned somewhere that you worried that simply deprecating SHA-1 certs as of 2017 could create a big customer service burden on Google as of late 2016 or early 2017.  I don’t think that’s the case with this new proposed policy, as all the negative UI effects will happen in 2014-15.  Plus, I predict Google will be deluged with customer service complaints under your current policy, when thousands of websites start showing as “untrusted” in the next 6-12 weeks.  Why not make life easier for Google with a revised policy?

So what do you think?  Can we make a change to the policy that is focused on the real problem (2017 certs)?

Thanks for your consideration.

Kirk R. Hall
Operations Director, Trust Services
Trend Micro

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