Capture Context Managers

After a crash of a capture campaign we might need to release resources (e.g., call scope.dis()). Python context-managers (see a tutorial on context-managers) help us to ensure resources are always released even in the case of capture in a script running on remote computer.

Automation Scripts

When using a JupyterLab notebook we can always ensure scope.dis() is called. However when a Python script crashes we no longer hold the scope variable and resuming capture is much more complicated. We could wrap everything by try-finally blocks. One of the advantages of using context managers is they prevent us from forgetting to add the finally block.

Try-Finally Solution

import time

import chipwhisperer as cw


def main():
    try:
        scope = cw.scope()
        scope.default_setup()
        time.sleep(1)
        target = cw.target(scope)

        target.con()
        time.sleep(1)
        scope.io.target_pwr = False
        time.sleep(1)
        scope.io.target_pwr = True

        ktp = cw.ktp.Basic()
        key, pt = ktp.new_pair()
        trace = cw.capture_trace(scope, target, pt, key)
        print(trace)
    finally:
        target.dis()
        scope.dis()


if __name__ == "__main__":
    main()

Context-Managers Solution

TODO