1. A method for securing communications over a system having a plurality of system users, each said user having an associated asymmetric crypto-key with a public key portion and a corresponding private key portion, each public key portion being accessible to the plurality of system users, each private key portion having a first private key portion known only to the associated user and a corresponding second private key portion, said method for securing communications between at least a first and second of said plurality of users comprising the steps of: generating, for the first user, a temporary asymmetric crypto-key having a first temporary key portion and an associated second temporary key portion; encrypting said second temporary key portion with the first private key portion of a first user crypto-key associated with the first user to form a first encrypted message; obtaining, for a third user, the second temporary key portion by applying the second private key portion of the first user crypto-key to the first encrypted message, thereby authenticating the first user to a third user; further encrypting the first encrypted message with the second private key portion of the first user crypto-key to form a second encrypted message; and obtaining, for the first user, the second temporary key portion by applying the public key portion of the first user crypto-key to decrypt the second encrypted message and thereby authenticating the third user to the first user.