How does C# generate GUIDs?

Question

How are GUIDs generated in C#?

Answer 1

The algorithm is documented here as Globally unique identifier

Answer 2

It depends. For .NET Core in Unix GUIDs, are generated by creating a random number of 128 bits and and doing a couple bit wise operations. In .NET Core for Windows and .NET framework it makes a remote procedure call to the Windows function UuidCreate (so it's completely up to your Windows version on how they are generated). For Unix and recent versions of Windows, you'll notice that there is one hex digit that is always a 4. That is because it the version number for the Uuid 4, which just means they are generated with random bytes. GUIDs used to be generated with things like the timestamp and MAC address, but that became an attack vector because it told end users information about the system and helped them predict future GUIDs easier.