Abstract: Embodiments of the invention reduce the probability of success of a DOS attack on a node receiving packets by decreasing the probability of random collisions of packets sent by a malicious user with those sent by honest users. The probability of random collisions may be reduced in one class of embodiments of the invention by supplementing the identification field of the IP header of each transmitted packet with at least one bit from another field of the header. The probability of random collisions may be reduced in another class of embodiments of the invention by ensuring that packets sent from a transmitting IPsec node to a receiving IPsec node are not fragmented.

Abstract: A system facilitates the purchase of an item or service using a wireless device (100). The system may capture an image of a bar code (310) associated with a device (300) from which the item or service is being purchased and transmit the image to facilitate payment for the item or service. The system may alternatively process the image to extract information from the image and transmit the extracted information to facilitate payment for the item or service.