Create a SAN certificate signing request for IIS web server

How to create a SAN certificate signing request for IIS web server?

  • Open Certificate MMC snap in for your computer
    • Click on Start – Run – MMC – File – Add/Remove Snap In – Select Certificates – Click Add – Select My Computer
  • Click on Personal – All Tasks – Advanced Operations – Create Custom request

  • Click next in Certificate Enrollment Wizard’s welcome window
  • Select “Proceed without enrollment policy” under Custom Request & click next
  • In Custom Request window Select (No template) Legacy key & PKCS #10 as request format
  • And Click Next

  • In Certificate Information Page click the Details icon then Properties. It will open up Certificate Properties window, where we can define different attributes.

  • Under Private Key, select key size. Over here I just left it as default. You may like to select 4096 for production servers.
  • Under Key Type select “Exchange

  • Under Extension tab select Extended Key Usage; add Server Authentication from the available options.

  • Under Subject Tab we will be defining our multiple DNS names for the certificate
  • From Drop down Subnet Name section select Common Name & type the value. Preferably the primary domain name & then click Add.
  • Under Alternative Name select DNS type all alternate DNS Names & add them.

  • Under General Tab type a friendly name.
  • Better to keep add a * in front of the friendly name now. It will help you to bind the certificate from IIS graphical user interface to all websites using same IP & port 443. If you don’t do this now, no worries, you can do it later or you can use Commadline tool to bind this cert. I have discussed the same in certificate installation/import post.
  • Click okay & In certificate information window click next

  • Give a file path to save this certificate request 7 select Base 64 as file format

  • It will generate “.req” file, you can open this file using notepad.
  • You use this file to generate your SAN certificate from external public certificate authority or from your internal certificate authority server.