A Code Signing certificate in macOS allows you to sign modules or programs using codesign tool. Code signing is a security measure used by Gatekeeper in macOS to allow only verified applications to execute.

Code Signing certificate can be generated using Keychain Access utility. It has to be issued by a Certified Authority (CA), which you need to create if you don't already have one.

Steps to create code signing certificate using Keychain Access:

  1. Launch Keychain Access.
  2. Go to Keychain AccessCertificate AssistantCreate a Certificate from the menu bar.
  3. Set the name of the certificate.
  4. Click on Identity Type select list.

  5. Select Leaf from the list.
  6. Click on Certificate Type select list.
  7. Select Code Signing from the list.
  8. Click Create to continue.
  9. Select CA or issuer from the list and click Create.

  10. Click Done to finish the process.