No, you do not lose attorney client privilege. However, your attorney does have to report the receipt of cash to the government. He/she need not, and is not permitted, to inform anyone of the nature of your engagement or divulge information that falls within the attorney-client privilege.
Marty Davidoff, email@example.com, 732-274-1600. This answer is provided for general information only. You should seek advice from an attorney or tax professional.