Generate Public Certificate From Private Key

admin 12.04.2020

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To sign an assembly with a strong name, you must have a public/private key pair. This public and private cryptographic key pair is used during compilation to create a strong-named assembly. You can create a key pair using the Strong Name tool (Sn.exe). Key pair files usually have an .snk extension.

Note

In Visual Studio, the C# and Visual Basic project property pages include a Signing tab that enables you to select existing key files or to generate new key files without using Sn.exe. In Visual C++, you can specify the location of an existing key file in the Advanced property page in the Linker section of the Configuration Properties section of the Property Pages window. The use of the AssemblyKeyFileAttribute attribute to identify key file pairs was made obsolete beginning with Visual Studio 2005.

Mar 29, 2016 We can extract the public key from the keystore using the following command. This generates a file called server.cert containing the public certificate from the server.jks keystore. In the same way we extracted the server’s public key, we can extract the. In case we generate the private key as well by rekey method of godaddy,then what is the procedure to install wildcard certificate on third party servers where we cant share the private key. Also in case it need to be shared what is the location where this private key need to be placed so that SSL cert can recognize it.

Create a key pair

To create a key pair, at a command prompt, type the following command:

sn –k <file name>

In this command, file name is the name of the output file containing the key pair.

The following example creates a key pair called sgKey.snk.

If you intend to delay sign an assembly and you control the whole key pair (which is unlikely outside test scenarios), you can use the following commands to generate a key pair and then extract the public key from it into a separate file. First, create the key pair:

Next, extract the public key from the key pair and copy it to a separate file:

Once you create the key pair, you must put the file where the strong name signing tools can find it.

When signing an assembly with a strong name, the Assembly Linker (Al.exe) looks for the key file relative to the current directory and to the output directory. When using command-line compilers, you can simply copy the key to the current directory containing your code modules.

If you are using an earlier version of Visual Studio that does not have a Signing tab in the project properties, the recommended key file location is the project directory with the file attribute specified as follows:

Create a self-signed root certificate

Use the New-SelfSignedCertificate cmdlet to create a self-signed root certificate. For additional parameter information, see New-SelfSignedCertificate.

From a computer running Windows 10 or Windows Server 2016, open a Windows PowerShell console with elevated privileges. These examples do not work in the Azure Cloud Shell 'Try It'. You must run these examples locally.
Use the following example to create the self-signed root certificate. The following example creates a self-signed root certificate named 'P2SRootCert' that is automatically installed in 'Certificates-Current UserPersonalCertificates'. You can view the certificate by opening certmgr.msc, or Manage User Certificates.
Leave the PowerShell console open if you want to create a client certificate right after creating this root certificate.

Generate a client certificate

Each client computer that connects to a VNet using Point-to-Site must have a client certificate installed. You generate a client certificate from the self-signed root certificate, and then export and install the client certificate. If the client certificate is not installed, authentication fails.

The following steps walk you through generating a client certificate from a self-signed root certificate. You may generate multiple client certificates from the same root certificate. When you generate client certificates using the steps below, the client certificate is automatically installed on the computer that you used to generate the certificate. If you want to install a client certificate on another client computer, you can export the certificate.

The examples use the New-SelfSignedCertificate cmdlet to generate a client certificate that expires in one year. For additional parameter information, such as setting a different expiration value for the client certificate, see New-SelfSignedCertificate.

Example 1 - PowerShell console session still open

Use this example if you have not closed your PowerShell console after creating the self-signed root certificate. This example continues from the previous section and uses the declared '$cert' variable. If you closed the PowerShell console after creating the self-signed root certificate, or are creating additional client certificates in a new PowerShell console session, use the steps in Example 2.

Modify and run the example to generate a client certificate. If you run the following example without modifying it, the result is a client certificate named 'P2SChildCert'. If you want to name the child certificate something else, modify the CN value. Do not change the TextExtension when running this example. The client certificate that you generate is automatically installed in 'Certificates - Current UserPersonalCertificates' on your computer.

Example 2 - New PowerShell console session

If you are creating additional client certificates, or are not using the same PowerShell session that you used to create your self-signed root certificate, use the following steps:

Identify the self-signed root certificate that is installed on the computer. This cmdlet returns a list of certificates that are installed on your computer.
Locate the subject name from the returned list, then copy the thumbprint that is located next to it to a text file. In the following example, there are two certificates. The CN name is the name of the self-signed root certificate from which you want to generate a child certificate. In this case, 'P2SRootCert'.
Declare a variable for the root certificate using the thumbprint from the previous step. Replace THUMBPRINT with the thumbprint of the root certificate from which you want to generate a child certificate.
For example, using the thumbprint for P2SRootCert in the previous step, the variable looks like this:
Modify and run the example to generate a client certificate. If you run the following example without modifying it, the result is a client certificate named 'P2SChildCert'. If you want to name the child certificate something else, modify the CN value. Do not change the TextExtension when running this example. The client certificate that you generate is automatically installed in 'Certificates - Current UserPersonalCertificates' on your computer.

Export the root certificate public key (.cer)

After creating a self-signed root certificate, export the root certificate public key .cer file (not the private key). You will later upload this file to Azure. The following steps help you export the .cer file for your self-signed root certificate:

To obtain a .cer file from the certificate, open Manage user certificates. Locate the self-signed root certificate, typically in 'Certificates - Current UserPersonalCertificates', and right-click. Click All Tasks, and then click Export. This opens the Certificate Export Wizard. If you can't find the certificate under Current UserPersonalCertificates, you may have accidentally opened 'Certificates - Local Computer', rather than 'Certificates - Current User'). If you want to open Certificate Manager in current user scope using PowerShell, you type certmgr in the console window.
In the Wizard, click Next.
Select No, do not export the private key, and then click Next.
On the Export File Format page, select Base-64 encoded X.509 (.CER)., and then click Next.
For File to Export, Browse to the location to which you want to export the certificate. For File name, name the certificate file. Then, click Next.
Click Finish to export the certificate.
Your certificate is successfully exported.
The exported certificate looks similar to this:
If you open the exported certificate using Notepad, you see something similar to this example. The section in blue contains the information that is uploaded to Azure. If you open your certificate with Notepad and it does not look similar to this, typically this means you did not export it using the Base-64 encoded X.509(.CER) format. Additionally, if you want to use a different text editor, understand that some editors can introduce unintended formatting in the background. This can create problems when uploaded the text from this certificate to Azure.

Export the self-signed root certificate and private key to store it (optional)

You may want to export the self-signed root certificate and store it safely as backup. If need be, you can later install it on another computer and generate more client certificates. To export the self-signed root certificate as a .pfx, select the root certificate and use the same steps as described in Export a client certificate.