Electronic transactions often include a payment phase. Payments can de executed using bank cards or using electronic cash. Privacy and security are desired features for these operations. Sometimes the purchase involves a physical product but services can be also purchased. E-tickets represent the purchase of a service and denote the right to use it. Following this line we have developed protocols of electronic cash, micropayments, e-ticketing and automatic fare collection.

Fair Exchange of values is a problem that aims to solve a scenario where N parties want to exchange some item, but none wants to give his item to the others unless he has an assurance that the others will give him the item he is waiting for. It has many applications, like digital signature of contracts, where the items to be exchanged are signatures on contracts, certified delivery of messages, where we exchange a message for evidence of receipt, or a payment process, where we exchange a payment (e-cash, visa, etc.) for digital goods or a receipt.

New and traditional services on wired networks should operate, at present, over wireless networks. Our research is focused in the benefits of the application of the Cross-Layer techniques in those aspects related to the security in wireless networks. One of these aspects is the use of efficient encryption mechanisms that can improve the overall performance of the device in 802.11 local area networks. Other aspect is the use of the Cross-Layer techniques as a solution to develop efficient intrusion detection systems.

It is important to analyze not only the technical aspects of electronic commerce solutions but also the related legal aspects and laws concerning this kind of electronic transactions. Taking advantage of our interdisciplinary research group in which there are researchers and collaborators form the law faculty, we also study how our theoretical findings can fit the real world.