What is the areas you would like to add the new feature to?

Notation CLI

Is your feature request related to a problem?

The environment variables NOTATION_USERNAME and NOTATION_PASSWORD are considered as insecure and not suitable for production since it is possible to leak them to its child processes like plugins.

What solution do you propose?

Remove those environment variables when spawning child process (i.e. plugin process) while keeping other environment variables.

What alternatives have you considered?

It is always good to configure a credential store.

Any additional context?

No response