Build the threat model

[binbin-li]

Describe the solution you'd like
We may need to analyze the security threats and vulnerabilities of Ratify via threat modeling.
With the threat modeling result, it can help us identify the potential threats and prove its security as a result.

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Environment:

• Ratify version: (use the image tag):
• Kubernetes version: (use kubectl version):