Group Policy has two Security Settings nodes. \Computer Configuration\Windows Settings\Security Settings is for security settings applying to all users who log on to the computer. This node has two subnodes: IP Security Policies on Active Directory, and Public Key Policies.
\User Configuration\Windows Settings\Security Settings is for security settings applying to users regardless of which computer they log on to. This node has a Public Key Policies subnode.
For more information on using these nodes, see Security settings