How to secure SSH Private key on Windows 10

Keys must only be accessible to the user they're intended for and no other account, service, or group.

• GUI: [File] Properties - Security - Advanced
  1. Owner: Set to the key's user
  2. Permission Entries: Remove all users, groups, and services, except for the key's user
  3. Set key's user to Full Control
     
     
• CLI:

  # Set Variable:
    Set Key="C:\Path\to\keyfile"
  
  # Remove Inheritance:
    Cmd /c Icacls %Key% /c /t /Inheritance:d
  
  # Set Ownership to Owner:
    Cmd /c Icacls %Key% /c /t /Grant %UserName%:F
  
  # Remove All Users, except for Owner:
    Cmd /c Icacls %Key%  /c /t /Remove Administrator BUILTIN\Administrators BUILTIN Everyone System Users
  
  # Verify:
    Cmd /c Icacls %Key%