Difference between revisions of "Working with SSL Certificates"

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Latest revision as of 13:35, 6 November 2024

Although various methods exist to create and import SSL certificates, this task can be laborious on Windows servers where no certificate policy exists (i.e. standalone servers). This article describes how to manually create and verify a certificate signing requests (CSR) and import the certificate after the CSR has been signed by a certificate authority, using Microsoft's Certreq tool.

Service Providers who already possess certificates and/or manage their certificates with OpenSSL/LibreSSL, find useful information in Importing an Existing Certificate.

Creating or Renewing a Certificate

Follow the below instructions to create or renew a certificate and import it into Windows' certificate store.

Generating a Certificate Signing Request (CSR)

It is assumed that the following steps are carried out on the machine, where the certificate is actually going to be used by MailStore SPE.

Prepare a text file request.inf with the following content:

;----------------- request.inf -----------------
[Version]
Signature="$Windows NT$"

[NewRequest]
; replace Subject attributes in the line below with real values
Subject = "CN=mailarchive.example.com, OU=Department, O=Organisation, L=Locality, S=State, C=Country"
KeySpec = 1
KeyLength = 2048
Exportable = TRUE
FriendlyName = mailarchive.example.com
MachineKeySet = TRUE
SMIME = False
PrivateKeyArchive = FALSE
UserProtected = FALSE
UseExistingKeySet = FALSE
ProviderName = "Microsoft RSA SChannel Cryptographic Provider"
ProviderType = 12
RequestType = PKCS10
KeyUsage = 0xa0
 
[EnhancedKeyUsageExtension]
OID = 1.3.6.1.5.5.7.3.1 ; this is for Server Authentication

[Extensions]
2.5.29.17 = "{text}"
_continue_ = "DNS=mailarchive.example.com&"
_continue_ = "DNS=archive.example.com&"
_continue_ = "DNS=*.example.com&"

Adjust the Subject and FriendlyName values according to your needs.
Adjust the Subject Alternative Names (SAN) in the [Extensions] section as well. Please note that the Common Name (CN) in the Subject is irrelevant for the verification by clients and that all host names must be included as SANs. Additional host names may be added with appending additional _continue_ lines.
Save the file.
Open an elevated command prompt and navigate to the directory where the request.inf is stored.
Create the CSR by executing the following command:

certreq -new request.inf request.csr

Validating the Certificate Signing Request

To verify that the CSR is correct, execute the following command to display it in a human readable format:

certutil -dump request.csr

Submitting the Certificate Signing Request

Submit the CSR to your preferred CA. The CA might ask for the server platform during the submission process. Selecting IIS 7 or None of the listed should be sufficient. After successful approval of the CSR, you will get the signed certificate in return.

Please note: Nowadays most CAs require the installation of intermediate CA certificates. Detailed information about the installation process of intermediate CA certificates is typically included in the electronic delivery of your certificate.

Importing the Certificate

Open an elevated command prompt and navigate to the directory where the certificate file is stored.
Execute the following command to import the certificate into the computer's personal certificate store:

certreq -accept certificate.cer

Verifying the Import

Log on as administrator to the server on which certificate has been imported.
Open the Microsoft Management Console (MMC)
Add the Certificate Snap-In by following these steps:
- Click on File > Add/Remove Snap-In > Certificate > Add >
- Select Computer Account and click on Next >
- Select Local Computer and click on Finish
- Close any open dialog windows
Click on Certificates (Local Computer) > Personal > Certificates
Double-click on the previously imported certificate
Make sure that the private key for the certificate is available.

Repairing the Certificate Store

Sometimes the matching private key cannot be found although the certificate was imported successfully into the correct certificate store. Try to repair the certificate store as follows:

Open an elevated PowerShell and execute the following command:

Get-ChildItem Cert:\LocalMachine\My | select Subject, Serialnumber, Thumbprint, HasPrivateKey

Check the subjects, serialnumbers and fingerprints of the installed certificates, to identify the certificate to be used by MailStore.
Repair the corresponding certificate store by executing the following command, where SerialNumber is the serial number of the certificate that should be used.

certutil -repairstore my SerialNumber

Using the Certificate

Replace the self-signed certificates in the Client Access Server.

Importing an Existing Certificate

Typically certificates are exchanged between computers by means of Personal Information Exchange (PFX/P12) containers. These can, for example, be created using the export functions of the MMC Snap-In Certificates.

Optional: Creating a PFX Container with OpenSSL/LibreSSL

When the original CSR was not created with Windows' own tools or not even created on a Windows computer, it is unlikely that the private key or the certificate is available in Windows' certificate store of the MailStore SPE computer, but stored on the file system instead.

In this case, a Personal Information Exchange (PFX) container needs to be created first. This container holds the certificate, private key, and all certificates of the certificate chain. After that, the PFX container can by imported into Windows' certificate store.

The following steps need to be executed to convert the certificate files into a PFX container with OpenSSL or LibreSSL:

Copy the certificate, private key and the certificates of the certificate chain into the OpenSSL or LibreSSL directory.
Open an elevated command prompt and navigate to this directory.
Create the PFX container by executing the following command, adjust the file names if necessary:

openssl pkcs12 -export -out certificate.pfx -inkey private_key.key -in certificate.crt -certfile chain_bundle_file.crt

In some case the created PFX container is not compatible with the Windows system and the import fails with a password error, even when the password is correct. In that case, append the -legacy parameter to the command:

openssl pkcs12 -export -out certificate.pfx -inkey private_key.key -in certificate.crt -certfile chain_bundle_file.crt -legacy

Importing a PFX container

Open an elevated command prompt and navigate into the directory where the PFX container resides.
Enter the following command to import the certificate into the personal store of the machine account, adjust the certificate file name if necessary:

certutil -importpfx -enterprise my certificate.pfx

Enter the password which is used to protect the PFX file.
Certutil shows a success message when the certificate was imported successfully.

@@ Line 1: / Line 1: @@
-__NOTOC__
 Although various methods exist to create and import SSL certificates, this task can be laborious on Windows servers where no certificate policy exists (i.e. standalone servers). This article describes how to manually create and verify a certificate signing requests (CSR) and import the certificate after the CSR has been signed by a certificate authority, using Microsoft's ''Certreq'' tool.
-Customers who manage their certificates with OpenSSL, find useful information at the end of this article.
+Service Providers who already possess certificates and/or manage their certificates with OpenSSL/LibreSSL, find useful information in [[#Importing an_Existing_Certificate|Importing an Existing Certificate]].
-== Generating a Certificate Signing Request (CSR) ==
+== Creating or Renewing a Certificate ==
+Follow the below instructions to create or renew a certificate and import it into Windows' certificate store.
+=== Generating a Certificate Signing Request (CSR) ===
 It is assumed that the following steps are carried out on the machine, where the certificate is actually going to be used by MailStore SPE.
@@ Line 32: / Line 34: @@
 [EnhancedKeyUsageExtension]
 OID = 1.3.6.1.5.5.7.3.1 ; this is for Server Authentication
+[Extensions]
+.5.29.17 = "{text}"
+_continue_ = "DNS=mailarchive.example.com&"
+_continue_ = "DNS=archive.example.com&"
+_continue_ = "DNS=*.example.com&"
 </pre>
 * Adjust the ''Subject'' and ''FriendlyName'' values according to your needs.
+* Adjust the ''Subject Alternative Names (SAN)'' in the ''[Extensions]'' section as well. Please note that the ''Common Name (CN)'' in the ''Subject'' is irrelevant for the verification by clients and that all host names must be included as SANs. Additional host names may be added with appending additional ''_continue_'' lines.
 * Save the file.
 * Open an elevated command prompt and navigate to the directory where the ''request.inf'' is stored.
@@ Line 39: / Line 48: @@
   certreq -new request.inf request.csr
-=== ''Optional:'' Subject Alternative Names (SAN) ===
+=== Validating the Certificate Signing Request ===
-If the certificate should be valid for multiple host names, so called Subject Alternative Named (SAN) must be included in the CSR. Add the ''Extensions'' section as shown below to the the end of the <tt>request.inf</tt> file and adjust the host names to your needs or add additional ones by appending additional ''_continue_'' lines. Then save the file and create the request as explained previously.
-<pre>
-[Extensions]
-.5.29.17 = "{text}"
-_continue_ = "DNS=mailarchive.example.com&"
-_continue_ = "DNS=archive.example.com&"
-</pre>
-<p class="msnote">'''Important notice:''' When SANs are defined, the CN in the ''Subject'' field will be ignored by clients. Therefore all valid host names have to be added to the SAN extension.</p>
-== Validating the Certificate Signing Request ==
 To verify that the CSR is correct, execute the following command to display it in a human readable format:
   certutil -dump request.csr
-== Submitting the Certificate Signing Request ==
+=== Submitting the Certificate Signing Request ===
 Submit the CSR to your preferred CA. The CA might ask for the server platform during the submission process. Selecting ''IIS 7'' or ''None of the listed'' should be sufficient. After successful approval of the CSR, you will get the signed certificate in return.
 <p class="msnote">'''Please note:''' Nowadays most CAs require the installation of intermediate CA certificates. Detailed information about the installation process of intermediate CA certificates is typically included in the electronic delivery of your certificate.</p>
-== Importing and Verifying the Certificate ==
+=== Importing the Certificate ===
 * Open an elevated command prompt and navigate to the directory where the certificate file is stored.
 * Execute the following command to import the certificate into the computer's personal certificate store:
@@ Line 67: / Line 64: @@
   certreq -accept certificate.cer
-* Use MMC's certificate snap-in or ''certlm.msc'' (Windows Server 2012 or newer only) to verify that the certificate has been imported properly in the computer's ''Personal'' certificate store and that a matching private key can be found.
+=== Verifying the Import ===
+* Log on as administrator to the server on which certificate has been imported.
+* Open the ''Microsoft Management Console (MMC)''
+* Add the Certificate Snap-In by following these steps:
+** Click on ''File'' > ''Add/Remove Snap-In'' > ''Certificate'' > ''Add >''
+** Select ''Computer Account'' and click on ''Next >''
+** Select ''Local Computer'' and click on ''Finish''
+** Close any open dialog windows
+* Click on ''Certificates (Local Computer)'' > ''Personal'' > ''Certificates''
+* Double-click on the previously imported certificate
+* Make sure that the private key for the certificate is available.
+==== Repairing the Certificate Store ====
+Sometimes the matching private key cannot be found although the certificate was imported successfully into the correct certificate store. Try to repair the certificate store as follows:
+* Open an elevated PowerShell and execute the following command:
+ Get-ChildItem Cert:\LocalMachine\My | select Subject, Serialnumber, Thumbprint, HasPrivateKey
+* Check the subjects, serialnumbers and fingerprints of the installed certificates, to identify the certificate to be used by MailStore.
+* Repair the corresponding certificate store by executing the following command, where ''SerialNumber'' is the serial number of the certificate that should be used.
+ certutil -repairstore my SerialNumber
+=== Using the Certificate ===
 * [[Replace_Self-signed_SSL_Certificates|Replace]] the self-signed certificates in the ''Client Access Server''.
-== Appendix: Creating a PFX Container with OpenSSL ==
+== Importing an Existing Certificate ==
-When the CSR was created with OpenSSL, the private key is never stored in the Windows certificate store. To use certificates that have been created with OpenSSL in MailStore, it is therefore required to merge the private key,   certificate and optionally the CA's certificate chain into a PFX container. This container can then be imported into Window's certificate store.
+Typically certificates are exchanged between computers by means of Personal Information Exchange (PFX/P12) containers. These can, for example, be created using the export functions of the MMC Snap-In ''Certificates''.
+=== Optional: Creating a PFX Container with OpenSSL/LibreSSL ===
+When the original CSR was not created with Windows' own tools or not even created on a Windows computer, it is unlikely that the private key or the certificate is available in Windows' certificate store of the MailStore SPE computer, but stored on the file system instead.
+In this case, a Personal Information Exchange (PFX) container needs to be created first. This container holds the certificate, private key, and all certificates of the certificate chain. After that, the PFX container can by imported into Windows' certificate store.
+The following steps need to be executed to convert the certificate files into a PFX container with OpenSSL or LibreSSL:
+* Copy the certificate, private key and the certificates of the certificate chain into the OpenSSL or LibreSSL directory.
+* Open an elevated command prompt and navigate to this directory.
+* Create the PFX container by executing the following command, adjust the file names if necessary:
+ openssl pkcs12 -export -out certificate.pfx -inkey private_key.key -in certificate.crt -certfile chain_bundle_file.crt
+* In some case the created PFX container is not compatible with the Windows system and the import fails with a password error, even when the password is correct. In that case, append the ''-legacy'' parameter to the command:
+ openssl pkcs12 -export -out certificate.pfx -inkey private_key.key -in certificate.crt -certfile chain_bundle_file.crt -legacy
-* Create the PFX container by executing the following command:
+=== Importing a PFX container ===
- openssl pkcs12 -export -out certificate.pfx -inkey privateKey.key -in certificate.crt -certfile CACert.crt
+* Open an elevated command prompt and navigate into the directory where the PFX container resides.
-* Open an elevated command prompt and navigate to the directory where the PFX file is stored.
+* Enter the following command to import the certificate into the personal store of the machine account, adjust the certificate file name if necessary:
-* Import the content of the PFX container into the computer's personal certificate store by executing the following command:
+  certutil -importpfx -enterprise my certificate.pfx
-  certutil -importpfx certificate.pfx
+* Enter the password which is used to protect the PFX file.
+* Certutil shows a success message when the certificate was imported successfully.
 == Weblinks ==
-* [https://technet.microsoft.com/en-us/library/dn296456.aspx Microsoft Technet: Certreq]
+* [https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/certreq_1 Microsoft Technet: Certreq]
-* [https://technet.microsoft.com/en-us/library/cc732443.aspx Microsoft Technet: Certutil]
+* [https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/certutil Microsoft Technet: Certutil]
-* [https://technet.microsoft.com/de-de/library/ff625722.aspx Microsoft Technet: How to Request a Certificate With a Custom Subject Alternative Name]
+* [https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/ff625722(v=ws.10) Microsoft Technet: How to Request a Certificate With a Custom Subject Alternative Name]
-* [https://www.openssl.org/docs/apps/openssl.html OpenSSL documentation]
+* [https://www.libressl.org/ LibreSSL]
+* [https://www.openssl.org/docs/apps/openssl.html OpenSSL Documentation]