Private & Public Key storage location -- iis security

Vicky
5/29/2006 8:33:01 AM

I am shocked to here that it is the CA who generates the Private & public key
(Key Pair) for my own website.
You seem to have shattered my understanding of the whole process. How can my
private ley be a private affair if the CA generates it for me (my website).
I think I need to build more clarity of the whole process. Maybe I have
wrong ideas.

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Vicky
5/29/2006 11:25:02 PM

Dear Bernard,

I have read all that stuff at the links you are refering to.
The pages on MS wesite lack clarity & I have wrote a comment to them such as

1] Under the section

"Obtain a Certificate"
"......The CSR is simply an encrypted text message that is encrypted with a
public/private key pair."

Now could it be made clear
A] if the website generates a Keypair of its own before it creates the CSR
B] How can the CSR be encrypted by Public/private key both at the same time?
C] Is it that the CSR contains both the private & public keys of the website?

What is true & presice ?

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Bernard Cheah [MVP]
5/30/2006 12:00:00 AM

Read -
How To Enable SSL for All Customers Who Interact with Your Web Site in
Internet Information Services
http://support.microsoft.com/?id=298805

that's why typically - we have trusted CA list in browser that we can trust.

--
Regards,
Bernard Cheah
http://www.iis.net/
http://www.iis-resources.com/
http://msmvps.com/blogs/bernard/

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Vicky
5/30/2006 6:19:01 AM

Dear Bernard,

As you say " To me, the issued cert from a trusted CA, contains both
public/private keys."

I would like to ask the following.

A] If the cert from a CA contains both public/private key & the cert is then
installed for your website, it will be sent to all the clients who connect to
that website. This way, the private key of the website is revealed to the
client & the purpose of achieving transaction level security is defeated.

B] If the CA is going to generate/derive/create a private key for my web
site, then what is private about the private key? I think the private key for
my website is & should only be know to my website & not to anyone else, not
even the CA.

C] I believe that a website cert contains the following important components
embedded (Correct me if I am wrong)
1] Issued to 2] issued by 3] validity 4] purpose 5] digital signature of CA
6] public key of the website

Regards

Vicky

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Bernard Cheah [MVP]
5/30/2006 6:58:50 PM

Well, I guessed it all depends on the discussion context.
Typically - CSR is encoded ASCII text with requested identification of the
computer, you can 'said' that public key is there, yes it is there, you can
also 'said' private key is also there, coz it will 'derive' or 'generate'
from it by the CA.

In normal context, typically CSR don't associate with public or private
keys, because you can't really use it yet.
It will become 'valid' once the CA has signed and generate the real
certificate, then the concept of public/private key popup.
I hope I didn't confuse you, I mean you can't really don't anything with the
so called 'keys' with the CSR.

Keys is only valid when the cert is issued. now -
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--
Regards,
Bernard Cheah
http://www.iis.net/
http://www.iis-resources.com/
http://msmvps.com/blogs/bernard/

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Bernard Cheah [MVP]
5/31/2006 12:00:00 AM

Alright -
a) when client connect to the SSL site, this is what's going on. Keys are
NOT sent, it just uses to encrypt and decrypt. client use the public key to
encrypt and server uses its private keys to decode.
Description of the Secure Sockets Layer (SSL) Handshake
http://support.microsoft.com/?id=257591

b) CA will need to sign it and the generate it. and they have to be trusted.
Keyword is 'trusted'. When you got the server cert file, it containts both
public and private keys. You will see 'You have the private key that
corresponds to this certiticate' when you view the cert.

c) Yes, and if that's the server cert issued from CA for your host server
authentication, it will has the private key as well. not to forgot some
other detail like the key usage (server or client auth), version, etc.

--
Regards,
Bernard Cheah
http://www.iis.net/
http://www.iis-resources.com/
http://msmvps.com/blogs/bernard/

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Vicky
5/31/2006 3:58:01 AM

Its difficult for me to digest as to what you say

"b) CA will need to sign it and the generate it. and they have to be trusted.
Keyword is 'trusted'. When you got the server cert file, it containts both
public and private keys. You will see 'You have the private key that
corresponds to this certiticate' when you view the cert."

well my understanding is that,

when the website makes a request for cert, it first generates a key pair at
its end & send only the public key to the CA along with the other websites
details in the request. The CA never know the private key of the website.

Well then the CA creates a electronic doc, we call as the webserver cert in
which it embedds the websites Public key & signs the cert with its own
digital signature.
The cert does not have the private key of the website. It is never disclosed
to anyone except the website itself.

After the cert is installed on the website & SSL enabled, Next when the
client connects to the website, the server cert is sent to the client for
verification. The client first verfies the digital signature of the CA in the
cert with the local Browser cert database. After the verification the client
generates a session key that it encrypts using the public key of the website
& the encrypted session key is sent to the website.

At the website end, upon receiving the encrypted session key, the website
uses its private key to decrypt it & now both the client & server have
something in common & that is the session key. The actual data tran/recp uses
the session key for encryption/decryption at both the ends.
The session key is discarded by both the client & server upon termination of
the session.

When you view the cert it does say that 'You have the private key that
corresponds to this certiticate' but it is not in the cert nor is it sent to
the webserver by the CA. The private key was generated by the website & is
stored on the local machine, never disclosed & sent anywhere, unless we
choose to export, in order to save it.

I just wanted to know the file system path where I can find the
Private/public key stored in IIS windows 2003 server.

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Vicky
6/1/2006 8:04:02 AM

Thanks Bernard For being there & sharing your experience & Knowledge.
There's something thats going in my mind, & wanted to explore & Experiment
more on it. So I wished I knew the file system path to the public & private
keys.

Vicky

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Bernard Cheah [MVP]
6/1/2006 6:27:17 PM

I should have been more specific, the 'certificate' is not consider a
certificate until is signed and INSTALLED at the machine generating the CSR,
with that you complete the 'certificate' to have both public and private key
in your certificate store.

You are referring to the signed 'electronic doc' while I'm focusing on the
'completed' certificate. To view the complete cert, you access the cert mmc,
and you will see the 'You have the private key that corresponds to this
certiticate', else this is just a pubic cert that the public key can be
obtain via CA.

I'm not aware of the actual system or file path of the certificate. It is
typically acces via certificate store using the certificate snap-in in MMC,
and you do your import and export in this interface rather than find the
'content' and back it up.

--
Regards,
Bernard Cheah
http://www.iis.net/
http://www.iis-resources.com/
http://msmvps.com/blogs/bernard/

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