Convert Enterprise Root CA to Standalone Root CA and create newSubordinate CAs

[Chris Morley]

Hi, my existing setup is/was simple. Had a single site active
directory for 30 users and an exchange server.

All computer workstation identification certs were pushed out via
autoenrollment and as such they trust the root CA which was the one to
issue the certificates.

As i will now have a number of sites i think it would be prudent to
have subordinate CAs at each remote location to issue certificates
there.

My question is, how would this affect the current computers having the
existing CA where it is directly issued from the enterprise root,
compared to other computers who were issued via the subordinate CA
when i get them running? Im guessing not much, since all computers
will trust the root anyway through thet certificate tree? Only down
side is if the root got comprimised in this scenario since they would
still trust it.

To aid my understanding, do enterprise root CA issue certificates to
workstations by default? Im guessing not, since i had to create a
workstation identification template.

How could i ensure in future that the root CA only issues certificates
for other subordinate CA's and NOT workstations? Would this be through
the certificate management mmc console? Is this controlled by active
directory GPO or some other setting?

What is the purpose of having a root enterprise CA and subordinate
enterprise CA? I cant see much benefit and indeedd maybe this is less
secure as the root is online... this is fine for small networks but i
have found may no longer be ideal for me.

Can active directory automatically publish the revocation list to http
for it to check? Do i need to have IIS running on the server? I see
the url for revocation checking but when i type it in in my browser i
get a blank page again i presume because IIS is not running.

Finally, given the site links are expanding, Is it possible to move my
existing enterprise root CA to a standalone root CA, and then create
multiple subordinate CAs to issue certs on the clients behalf? This
would be the ideal setup as a managed upgrading process. Can i move
the root enterprise CA to an offline root CA?

Many thanks in advance,

Chris

 

[Paul Adare]

Re: Convert Enterprise Root CA to Standalone Root CA and create new Subordinate CAs

On Tue, 18 Mar 2008 22:45:03 -0700 (PDT), Chris Morley wrote:

> Hi, my existing setup is/was simple. Had a single site active
> directory for 30 users and an exchange server.
>
> All computer workstation identification certs were pushed out via
> autoenrollment and as such they trust the root CA which was the one to
> issue the certificates.

This is not why they trust the root. They trust the root because the root
CA is an Enterprise root which means its CA certificate gets published to
Active Directory and gets installed in the Trusted Root store on client
computers in the forest through Group Policy.
>
> As i will now have a number of sites i think it would be prudent to
> have subordinate CAs at each remote location to issue certificates
> there.
>
> My question is, how would this affect the current computers having the
> existing CA where it is directly issued from the enterprise root,
> compared to other computers who were issued via the subordinate CA
> when i get them running?

It would not affect the existing certificates at all.

> Im guessing not much, since all computers
> will trust the root anyway through thet certificate tree? Only down
> side is if the root got comprimised in this scenario since they would
> still trust it.

Which is why it is generally a bad idea to use an Enterprise root which
must, by definition, be on the network. For 30 users and internal only
certificates you're likely ok with an online Enterprise root.

>
> To aid my understanding, do enterprise root CA issue certificates to
> workstations by default? Im guessing not, since i had to create a
> workstation identification template.

What certificates get issued depends on what certificate templates are
published at an Enterprise CA, whether it is a root or subordinate.

>
> How could i ensure in future that the root CA only issues certificates
> for other subordinate CA's and NOT workstations? Would this be through
> the certificate management mmc console? Is this controlled by active
> directory GPO or some other setting?

Use the Certification Authority console to remove all of the certificate
templates that are published at the root except for the SubCA template.

>
> What is the purpose of having a root enterprise CA and subordinate
> enterprise CA? I cant see much benefit and indeedd maybe this is less
> secure as the root is online... this is fine for small networks but i
> have found may no longer be ideal for me.

For a small network having an online Enterprise root CA simply makes it
easier as you don't have to manually publish either the root CA certificate
or root CA CRL to the directory, it happens automatically.

>
> Can active directory automatically publish the revocation list to http
> for it to check?

Active Directory has nothing to do with this, the CA however can
automatically publish to an HTTP location.

> Do i need to have IIS running on the server? I see
> the url for revocation checking but when i type it in in my browser i
> get a blank page again i presume because IIS is not running.

The CA does not require IIS unless you want to use the web enrollment pages
or if you are using it to host CRLs.

>
> Finally, given the site links are expanding, Is it possible to move my
> existing enterprise root CA to a standalone root CA, and then create
> multiple subordinate CAs to issue certs on the clients behalf? This
> would be the ideal setup as a managed upgrading process. Can i move
> the root enterprise CA to an offline root CA?

No, you can't move a root from one type to another, you'd need to install a
new root as an offline standalone root and then manually publish its
certificate and CRL.


--
Paul Adare
MVP - Virtual Machines
http://www.identit.ca
Semi-conductor: A person hired to lead an orchestra before he has
graduated
from director's school.

 

[Chris Morley]

> > Finally, given the site links are expanding, Is it possible to move my
> > existingenterpriserootCAto astandalonerootCA, and then create
> > multiple subordinate CAs to issue certs on the clients behalf? This
> > would be the ideal setup as a managed upgrading process. Can i move
> > therootenterpriseCAto an offlinerootCA?
>
> No, you can't move arootfrom one type to another, you'd need to install a
> newrootas an offlinestandalonerootand then manually publish its
> certificate and CRL.
>
> --
> Paul Adare
> MVP - Virtual Machineshttp://www.identit.ca
> Semi-conductor:  A person hired to lead an orchestra before he has
> graduated
> from director's school.

Dear Paul,

Many thanks for the informative reply. We will actually have over 70
users within the next year split across multiple sites, i therefore
believe its prudent to take the pain now and move to a offline root
architecture with subordinate enterprise CAs at each site to issue
certs. I only have two Windows Mobile phones so it wont be too much
trouble to install the new certificates.

Do you have any advice on howto do this? I'm thinking something along
the following:

1) Create a new offline root CA
2) Commission new subordinate enterprise CA at each site (or make sure
VPN works to ensure certs can be auto enrolled to clients)
3) Publish new Workstation identification templates on the subordinate
CA
4) Check all new templates have been pushed to clients and the new
offline root CA is trusted
5) Create new IIS template for exchange with the new offline root CA
trusted chain
6) Uninstall old enterprise root CA

What happens where i have this two certificate authority setup with
multiple auto enrollment for multiple certificate servers? Will active
directory ensure that clients request templates from the new
subordinate CAs? Or does a client simply contact the first certificate
server that it can see?

Finally, how can i ensure that external clients can see the CRL
published via http? I cant find the place where i can change this
string in the certificate template before it is published via auto
enrollment.

Many thanks,

Chris

 

[Chris Morley]

On 21 Mar, 12:33, Chris Morley <morl...@gmail.com> wrote:
> > > Finally, given the site links are expanding, Is it possible to move my
> > > existingenterpriserootCAto astandalonerootCA, and then create
> > > multiple subordinate CAs to issue certs on the clients behalf? This
> > > would be the ideal setup as a managed upgrading process. Can i move
> > > therootenterpriseCAto an offlinerootCA?
>
> > No, you can't move arootfrom one type to another, you'd need to install a
> > newrootas an offlinestandalonerootand then manually publish its
> > certificate and CRL.
>
> > --
> > Paul Adare
> > MVP - Virtual Machineshttp://www.identit.ca
> > Semi-conductor:  A person hired to lead an orchestra before he has
> > graduated
> > from director's school.
>
> Dear Paul,
>
> Many thanks for the informative reply. We will actually have over 70
> users within the next year split across multiple sites, i therefore
> believe its prudent to take the pain now and move to a offline root
> architecture with subordinate enterprise CAs at each site to issue
> certs. I only have two Windows Mobile phones so it wont be too much
> trouble to install the new certificates.
>
> Do you have any advice on howto do this? I'm thinking something along
> the following:
>
> 1) Create a new offline root CA
> 2) Commission new subordinate enterprise CA at each site (or make sure
> VPN works to ensure certs can be auto enrolled to clients)
> 3) Publish new Workstation identification templates on the subordinate
> CA
> 4) Check all new templates have been pushed to clients and the new
> offline root CA is trusted
> 5) Create new IIS template for exchange with the new offline root CA
> trusted chain
> 6) Uninstall old enterprise root CA
>
> What happens where i have this two certificate authority setup with
> multiple auto enrollment for multiple certificate servers? Will active
> directory ensure that clients request templates from the new
> subordinate CAs? Or does a client simply contact the first certificate
> server that it can see?
>
> Finally, how can i ensure that external clients can see the CRL
> published via http? I cant find the place where i can change this
> string in the certificate template before it is published via auto
> enrollment.
>
> Many thanks,
>
> Chris- Hide quoted text -
>
> - Show quoted text -

Sorry I also forgot to ask does anyone know if i need to publish
separate CRL locations for the subordinate CAs in addition to the root
CA CRL?

Thanks again,

Chris