In this paper, we have presented several algorithms based on distributed secure multiparty computation. We have applied these algorithms to develop e-negotiation protocols for collaborative supply chain planning. Preserving the privacy of the participants' data is an important issue in these protocols. The first protocol supports a policy of non-discriminatory pricing where the buying firms do not want to reveal their bids regarding price and demand before the supplier announces a fixed selling price common for all the buyers. Price is never disclosed for any buyer in this negotiation. In the second protocol we relax the assumption for the discrimination of prices for different buyer agents. The protocol attempts to find the joint gains between the buyers and seller by optimizing the total cost of the supply chain without disclosure of total cost or individual costs to each other or the mediator agent used for the purpose.