Abstract: A personal computer transmits encrypted information identifying a transaction card, together with a serial number of an encryption unit in which the information way encrypted, over a public network to a payment server. The payment server generates a single-use credit card number, which is returned to the personal computer over the public network, and stores the single-use credit card number together with the serial number and the encrypted information. The personal computer then transmits the single-use credit card number to a merchant's server through which a transaction is to be made. The single-use credit card number is transmitted to the payment server, which is identified according to a portion of the single-use credit card number. The payment server then decodes a portion of the encoded information according to a cryptogram located within a data base according to the serial number stored with the single-use credit card number.

Abstract: A private network is built by first allowing a pre-determined number of client systems to connect directly to a server system. After this occurs, additional client systems requesting connection are furnished with the addresses of client systems already connected within the private network. Each of the additional client systems then makes connections with a multiple number of client systems to receive information from the server system. Each of these client systems subsequently accepts connections from up to a second pre-determined number of client systems to which it transmits information received from the server system.