This would be confusing necessary for sufficient. The premise is saying: "If you resign, then it is necessary that you are convicted." The conclusion is saying: "If you are convicted, it is necessary that you resigned." However, this is not right; there could be a variety of other reasons for you getting convicted other than resigning. We don't know what those reasons are from the info here, but have no reason to think that the ONLY way to get convicted is by resigning.