In this paper, we have designed an electronic market where a buyer negotiates with n suppliers to procure p types of items within a given time frame. A privacy preserving 1-n-p negotiation protocol has been developed based on secure group communication and secure multiparty computation. The suppliers submit their bids. The objective is to label the bids as winning or losing so as to minimize the buyer's cost with the constraint that the buyer obtains all items in required quantity. The negotiation process has two distinct phases ? Pre-bid and Final bid. During pre-bid phase, the suppliers singly or jointly bid for a combination of items. The privacy requirements considered are: a) Pre-bid: forward and backward privacy and anonymity of the winner in each pre-bid cycle. b) Final bid: anonymity of the losers and traceability of the winners.