[cabfpub] Guidance on Microsoft SHA1 Deprecation Policy

Tom Albertson tomalb at microsoft.com
Thu Jan 23 16:28:07 UTC 2014

The SHA1 deprecation policy is not intended to apply to roots distributed outside the Windows root cert program.  This policy does not affect certificates that chain up to privately deployed root CAs. Administrators will have the option to enable the no SHA1 policy from Group Policy.

From: Doug Beattie [mailto:doug.beattie at globalsign.com]
Sent: Wednesday, January 22, 2014 3:30 PM
To: Tom Albertson
Cc: 'CABFPub'
Subject: RE: [cabfpub] Guidance on Microsoft SHA1 Deprecation Policy

Thanks Tom.

I'm sorry to keep asking follow up questions, but I assume this applies to Roots that are not distributed within the MS program as well.  Just wanted to confirm that private root customers (including large government PKIs)  also need to comply, not just the public CAs and their publicly trusted roots.


From: Tom Albertson [mailto:tomalb at microsoft.com]
Sent: Wednesday, January 22, 2014 5:29 PM
To: Doug Beattie; CABFPub
Subject: RE: [cabfpub] Guidance on Microsoft SHA1 Deprecation Policy

Hi Doug,

The SHA1 deprecation policy states that Windows Vista and later will stop accepting SHA1 end-entity certificates by the deadlines given.  This will apply to all certificates issued under the root hierarchy including SSL, secure email, client authentication, and code signing.  We expect all certificate types excluding code signing and time stamping to follow the SSL deprecation schedule.

From: public-bounces at cabforum.org<mailto:public-bounces at cabforum.org> [mailto:public-bounces at cabforum.org] On Behalf Of Doug Beattie
Sent: Wednesday, January 22, 2014 8:42 AM
Subject: [cabfpub] Guidance on Microsoft SHA1 Deprecation Policy

The Microsoft policy is located here, as I'm sure you all know:

The policy clearly states the scope of this policy is for SSL and Code Signing, but I wanted to validate that this is in-fact the entire set of users which will be impacted in 2017.

While not clear in the blog, in side discussions it became evident that that all CAs in the hierarchy of an SSL or Code Signing certificate (except the root) must also be SHA2.  This makes sense even if not explicitly stated (it should be stated at some point).  This means legacy SHA1 Intermediates cannot be used to sign subordinate SHA2 CAs and be trusted in 2017 for SSL and Code Signing certificates.

I wanted for inquire about personal certificates used for secure mail, client authentication to web sites (including Microsoft web servers), document signing (outside of Adobe), file encryption, etc.  Will SHA1 certificates and CA hierarchies continue to be trusted by Microsoft within these applications, or is Microsoft rolling out new validation logic globally for all certificates?

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