Abstract: A mechanism for securing bid proposals until close of tendering is provided for an electronic tendering system over an open network. In order to be permitted to file a bid electronically in response to an invitation to tender, prospective vendors encrypt their bid proposals using session keys obtained from a third party source. The encrypted proposals are filed with the bid requester who does not have access to the session keys while the tendering period remains open. The encrypted bid proposals are cached in a safe repository until close of tendering. In one embodiment, the bid requester itself holds onto the encrypted proposals, and obtain the session keys for accessing their contents from the third party on expiry of the bid submission period. In another embodiment, the bid requester double-encrypts each encrypted bid proposal as it is received using its own privately-held key, and forwards the double-encrypted proposals to the third party to hold in a safe repository until the close of tendering.