Generate Csr With Public Key

What is a CSR? A CSR or Certificate Signing request is a block of encoded text that is given to a Certificate Authority when applying for an SSL Certificate. It is usually generated on the server where the certificate will be installed and contains information that will be included in the certificate such as the organization name, common name (domain name), locality, and country. It also contains the public key that will be included in the certificate. A private key is usually created at the same time that you create the CSR, making a key pair. A CSR is generally encoded using ASN.1 according to the PKCS #10 specification.

A certificate authority will use a CSR to create your SSL certificate, but it does not need your private key. You need to keep your private key secret. The certificate created with a particular CSR will only work with the private key that was generated with it. So if you lose the private key, the certificate will no longer work.

Create a CSR in C# using an explicit RSA key-pair. Using the OpenSSL libraries one can create a CSR (certificate signing request) by doing this: where config.txt contains the distinguished name to use in the certificate. I would like to do something similar under Windows using C#.

What is contained in a CSR?

Common NameThe fully qualified domain name (FQDN) of your server. This must match exactly what you type in your web browser or you will receive a name mismatch error.


OrganizationThe legal name of your organization. This should not be abbreviated and should include suffixes such as Inc, Corp, or LLC.Google Inc.
Organizational UnitThe division of your organization handling the certificate.Information Technology
IT Department
City/LocalityThe city where your organization is located.Mountain View
State/County/RegionThe state/region where your organization is located. This shouldn't be abbreviated.California
CountryThe two-letter ISO code for the country where your organization is location.US
Email addressAn email address used to contact your organization.[email protected]
Public KeyThe public key that will go into the certificate.The public key is created automatically

What does a CSR look like?

Most CSRs are created in the Base-64 encoded PEM format. This format includes the '-----BEGIN CERTIFICATE REQUEST-----' and '-----END CERTIFICATE REQUEST-----' lines at the begining and end of the CSR. A PEM format CSR can be opened in a text editor and looks like the following example:


How do I generate a CSR and private key?

You need to generate a CSR and private key on the server that the certificate will be used on. You can find instructions in your server documentation or try the instructions from one of these certificate authorities:

Comodo CSR Generation Instructions
DigiCert CSR Generation Instructions
Entrust CSR Generation Instructions
GeoTrust CSR Generation Instructions
Thawte CSR Generation Instructions

Once you have your CSR generated, you can use our SSL Wizard to find the best SSL certificate that will meet your needs. If you are familiar with OpenSSL you can use the following command to generate a CSR and private key:

openssl req -new -newkey rsa:2048 -nodes -out servername.csr -keyout servername.key

How do I decode a CSR?

You can easily decode your CSR to see what is in it by using our CSR Decoder. In order to decode a CSR on your own machine using OpenSSL, use the following command:

openssl req -in server.csr -noout -text

What is a CSR/Private Key's bit length?

The bit-length of a CSR and private key pair determine how easily the key can be cracked using brute force methods. As of 2016, a key size of less than 2048 bits is considered weak and could potentially be broken in a few months or less with enough computing power. If a private key is broken, all the connections initiated with it would be exposed to whomever had the key. The Extended Validation guidelines that SSL certificate providers are required to follow, require that all EV certificates use a 2048-bit key size to ensure their security well into the future. Because of this, most providers encourage 2048-bit keys on all certificates whether they are EV or not.

Originally posted on Sun Dec 7, 2008


This document describes the procedure to generate certificates which have to be uploaded with every fresh installation of AMP Virtual Private Cloud (VPC). With the introduction of AMP Private Cloud 3.X, hostnames and certificate/key pairs are required for all of the following services:

  • Administration Portal
  • Authentication (new in Private Cloud 3.X)
  • FireAMP Console
  • Disposition Server
  • Disposition Server - Extended Protocol
  • Disposition Update Service
  • Firepower Management Center

Here, we will discuss a quick way to generate and upload the required certificates. You may tweak each of the parameters, including the hashing algorithm, key size, and others, as per your organization's policy, and your mechanism of generating these certificates might not match with what is detailed here.


Components Used

Cisco recommends that you have knowledge of these topics:

  • Windows Server 2008 onwards
  • AMP Private Cloud installation
  • Public Key Infrastructure


The information in this document is based on these software and hardware versions:

  • Windows Server 2008
  • CentOS 7
  • AMP Virtual Private Cloud 3.0.2

Warning: The procedure mentioned below can vary as per your CA server configuration. It is expected that the CA server of your choice is already provisioned and the configuration of the same has been completed. The following technote just describes an example of generating the certificates and Cisco TAC will not be involved in troubleshooting issues related to certificate generation and/or CA server issues of any kind.

Generate Certificates on Window Server

Ensure that the following roles are installed and configured on your Windows Server.

  • Active Directory Certificate Services
  • Certification Authority
  • Certification Authority Web Enrollment
  • Online Responder
  • Certificate Enrollment Web Service
  • Certificate Enrollment Policy Web Service
  • Active Directory Domain Services
  • DNS Servers
  • Web Server (IIS)

Generate a Certificate Signing Request (CSR)

Step 1. Navigate to MMC console, and add the Certificates snap-in for your computer account as shown in the image here.

Step 2. Drill down Certificates (Local Computer) > Personal > Certificates.

Step 3. Right click on the empty space and select All Tasks > Advanced Operations > Create Custom Request

Step 4. Click Next at the Enrollment window.

Step 5. Select your certificate enrollment policy and click Next.

Step 6. Choose the template as Web Server and click Next.

Step 7. If your 'Web Server' template has been configured correctly and is available for enrollment, you will see the status as 'Available' here. Click 'Details' to expand click on Properties.

Step 8. At a minimum, add the CN and DNS attributes. The rest of the attributes can be added as per your security requirements.

Step 9. Optionally, give a Friendly Name under the General tab.

Step 10. Click on the PrivateKey tab and ensure that you're enabling Make private key exportable under the Key Options section.

Step 11. Finally, click on OK. This should lead you to the Certificate Enrollment dialog from where you can click on Next.

Step 12. Browse to a location to save the .req file which will be submitted to the CA server for signing.


Submitting the CSR to the CA and generating the certificate

Step 1. Navigate to your MS AD Certificate Services Web Page as below and click 'Request a Certificate'

Step 2. Click on the advanced certificate request link.

Step 3. Click on Submit a certificate request by using a base-64-encoded CMC or PKCS #10 file, or submit a renewal request by using a base-64-encoded PKCS #7 file.

Step 4. Open the contents of the previously saved .req file (CSR) via Notepad. Copy the contents and paste it here. Ensure that the Certificate Template is selected as Web Server

Step 5. Finally, click on Submit.

Step 6. At this point, you should be able to Download the certificate as shown in the image here.

Exporting the Private Key and converting to PEM format

Step 1. Install the certificate into your Certificate Store by opening the .cer file and clicking on Install Certificate.

Step 2. Navigate to the MMC snap-in that was selected earlier.

Step 3. Navigate to the store where the certificate was installed.

Step 4. Right click the correct certificate, select All Tasks > Export.

Step 5. At the Certificate Export Wizard, confirm to export the private key as shown in the image.

Step 6. Enter a password and click Next to save the private key on your disk.

Step 7. This will save the private key in .PFX format, however, this needs to be converted to .PEM format to use this with AMP VPC.

Step 8. Install OpenSSL libraries from here:

Step 9. Open a command prompt window and change to the directory where you installed OpenSSL.

Step 10. Run the following command to extract the private key and save it to a new file: (If your PFX file is not in the same path as where the OpenSSL library is stored, you will have to specify the exact path along with the filename)

Step 11. Now run the following command to also extract the public cert and save it to a new file:

Generate Certificate on Linux Server

Ensure that the Linux server that you're trying to generate the required certificates has the OpenSSL libraries installed. Verifying if this and the procedure listed below will vary from the Linux distribution that you're running. This portion has been documented, as done on a CentOS 7 server.

Generate Self Signed RootCA

Step 1. Generate the Private Key for Root CA certificate

Step 2. Generate the CA certificate

Generate a certificate for each service

Create the certificate for Authentication, Console, Disposition, Disposition-Extended, Update server, Firepower Management Center(FMC) service as per the DNS name entry. You need to repeat below certificate generate process for each service (Authentication, Console etc.)

Generate Private key

Replace the <example.key> with actual certificate key such as Auth-Cert.key.

Generate CSR

Replace the <example.csr> with actual certificate CSR such as Auth-Cert.csr

Generate Csr From Public Key

Generate Certificate

Replace <example.csr>, <example.crt> with actual certificate CSR and certificate name

Adding The Certificates to AMP VPC

Step 1. Once the certificates are generated from any of the above methods, upload the corresponding certificate for each of the services. If they have been generated correctly, all the check marks are enabled as seen in the image here.

How To Generate Csr With Private Key


There is currently no verification procedure available for this configuration.


Generate Csr Ubuntu

There is currently no specific troubleshooting information available for this configuration.