J. D. Tygar. Atomicity in electronic commerce. In Proceedings of the 15th Annual ACM Symposium on Principles of Distributed Computing (PODC '96), pages 8--26, Philadelphia, PA, May 1996. ACM Press.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....both classical transactions as well as non transactional processes together into a unit of work that reflects the semantics and behavior of their underlying business task. Thirdly, they are governed by unconventional types of atomicity. We may distinguish between four broad types of atomicity [11]: Payment atomicity. Payment atomic protocols effect the transfer of funds from one party to another. Payment atomicity is the basic level of atomicity that each electronic commerce protocol should satisfy. Goods atomicity. Goods atomicity protocols are payment atomic, and also allow an ....

Tygar, J.D. Atomicity in electronic commerce. ACM---Mixed Media, Apr. 1998.

....BTs usually involve the actual delivery of purchased items (tangible or non tangible) The operational level atomicity primitives introduced in the following govern such transactions. The notion of operational level atomicity introduced in this paper refines similar principles reported in [36] and applies them to transaction aware web services. Payment atomicity. Payment atomic protocols affect the transfer of funds from one party to another. Payment atomicity is the basic level of atomicity that each operational level BT should satisfy. For many e business applications ....

J. D. Tygar, "Atomicity in electronic commerce," ACM-Mixed Media, April 1998.

....corresponding transactional mechanism in the m commerce environment that is intertwined with security, privacy, authentication, and authorization mechanisms. As special e commerce transactions, m commerce transactions complying with the model should guarantee the atomicity notions introduced in [20] for e commerce, which as such can be formulated as special kind of semantic constraints between subtransactions of S transactions (cf. 21,23] In the sequel we deepen the above analysis about the need and form of transaction modeling for m commerce environments. In section 2 we relate business ....

....running at Java enabled terminals, such as Nokia 9210. M commerce transactions can be viewed as transactional workflows and are relatives of Stransactions, i.e. structurally RDAGs, long lasting, contain cancellations and real actions. A form of semantic atomicity (preferably certified delivery [20]) is the property they try to enforce. Due to hostility of the environment, and vulnerability of PTDs, security and privacy must be intertwined with the transaction model and its realisation. The m commerce environment is global, highly autonomous and heterogeneous due to roaming, different ....

J. D. Tygar, Atomicity in Electronic Commerce. In Proceedings of the 15th PODC Conference, 1996: 8-26.

.... of fairness has to be realized with a trusted third party (also called trustee or TTP) as protocols without a TTP (e.g. EGL82,BOGMR90, Jak95, BN00] cannot guarantee this strong notion of fairness [EY80] A simple fair exchange solution is an active TTP that is involved in every exchange (e.g. [BP90, Tyg96, CHTY96, ZG96, FR97]) Much more e cient are optimistic protocols [ASW97] in which the TTP only has to participate if a con ict has to be resolved. Under the assumption that errors occur rarely these optimistic protocols minimize the number of requests to the TTP and thus prevent that it becomes a bottleneck during ....

....for this party will be lost nor that a successful exchange will be changed to an aborted exchange or vice versa) The e ectiveness property only rules out trivial protocols that do not exchange anything. The fairness property is sometimes called strong fairness [ASW97, Aso98] or atomicity [Tyg96] and ensures that party P will not be disadvantaged in the exchange, even if Q misbehaves and tries to cheat P . Fair exchange protocols provide fairness to both parties. The termination property ensures that P can eventually stop the protocol execution, even if Q does not follow the protocol. ....

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J. D. Tygar. Atomicity in electronic commerce. In Proceedings of the 15th Annual ACM Symposium on Principles of Distributed Computing (PODC '96), pages 826, Philadelphia, PA, May 1996. ACM Press.

....the capabilities of the trustee are limited to the exchange of the payment against the decryption key of the product. But as the decrypted product might still turn out to be incorrect, the protocol can only achieve weak fairness F 2 F 3 in an external dispute. The NetBill payment protocol [43] uses a similar idea to ensure fairness. P 8 : Another fair exchange variant with active trustee. Module combination hI 1 ; I 2a ; I 5a i is a variation of protocol P 1 . After the exchange has been prepared in I 2a , an active trustee is used to nally perform the swap of product and payment ....

....strong fairness cannot be achieved because it cannot be guaranteed that both protocol parts are executed atomically. However, the non repudiation proofs can be used in an external dispute to establish weak fairness. Atomicity was identi ed as a generic property of ecommerce protocols by Tygar [43]. The understanding is closely related to the notion of an atomic transaction from the eld of databases and comprises all the usual properties of fair exchange including non repudiation. Viewing fair exchange as a distributed transaction has conceptual advantages since it o ers an analogy to a ....

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Tygar, J. D. (1996) Atomicity in electronic commerce. Proceedings of the 15th Annual ACM Symposium on Principles of Distributed Computing (PODC '96), Philadelphia, PA, May, pp. 8-26, ACM Press, New York.

....system. If the network crashes in the middle of the withdrawal or payment protocol, some disputes such as losing e cash, repudiation, and no procurement of goods even after a full payment will happen. Under a network model where customers purchase electronic goods and receive its service, Tygar [18] introduced the problem of atomicity in electronic transactions and defined three classes of atomicity; money atomic, goods atomic, and certified delivery. Camp et al. 19] proposed a method to support atomicity using on line TTP(Trusted Third Party) Moreover, Sirbu and Tygar [20] and Bellare et ....

J. D. Tygar, "Atomicity in electronic commerce," in Proc. of Fifteen Annual ACM Symposium on Principles of Distributed Computing, Philadelphia, 1996, pp. 8--26.

....encrypted delivery. A large effort is also made to address fault tolerance and provide atomicity of payments, where the transaction either fully completes or appears never to have occurred. While we note that there has been recent work on the importance of fault tolerance in electronic payments [CHTY96, Tyg96, PW97, XYZZ99], we do not agree that it is important in a micropayment scheme if its presence significantly increases overheads. If, every once in a while, the value of a single micropayment is lost, it is not a huge concern. Every day, similar amounts are lost in malfunctioning vending machines or payphones ....

J. Tygar. Atomicity in electronic commerce. In Proceedings of the 15 th Annual ACM Symposium on Principles of Distributed Computing (PODC'96), pp. 8-26, Philadelphia, May 1996.

....party. The third party verifies the customer s financial information and forwards the payment token to the merchant and the decrypting key to the customer. Thus we ensure that fairness is established in the protocol. A Fair exchange E commerce Protocol with Automated Dispute Resolution 29 Tygar [7] has identified three desirable properties of a secure e commerce protocol. These are the money atomicity, goods atomicity and certified delivery properties. To prevent any misbehavior during the execution of the protocol, we propose a new property which we call the validated receipt property. ....

J. D. Tygar. Atomicity in Electronic Commerce. In Proceedings of the 15th Annual ACM Symposium on Principles of Distributed Computing, pages 8--26, May 1996.

....protocols ensure that the information exchanged between the parties is protected from unauthorized disclosure and modification. Moreover, researchers have identified several other desirable properties of e commerce protocols. Examples of these properties include money atomicity and goods atomicity [18], and validated receipt [14] Money atomicity ensures that money is neither created nor destroyed in the course of an e commerce transaction. Goods atomicity ensures that a merchant receives payment if and only if the customer receives the product. Validated receipt ensures that the customer is ....

J. D. Tygar. Atomicity in Electronic Commerce. In Proceedings of the 15th Annual ACM Symposium on Principles of Distributed Computing, pages 8--26, May 1996.

....knowing each other s identity. Therefore it is important that the exchange is performed fairly, i.e. in such a way that neither party is in danger of su ering a disadvantage. This led to the development of network protocols that allow the fair exchange of digital items over electronic networks [BP90,Tyg96,ZG97,ASW97,Aso98,VPG99]. Fair exchange protocols are not easy to design in environments like the Internet where the quality of service of the network is rather unpredictable. If a vendor sends a music le to a customer, there is no guarantee that it will reach its destination within a certain time. Consequently, fair ....

J. D. Tygar. Atomicity in electronic commerce. In Proceedings of the 15th Annual ACM Symposium on Principles of Distributed Computing (PODC'96), pages 826, New York, May 1996. ACM.

....party s expectations which might go beyond. So overall, we must assume that for the items a sufficiently accurate specification exists against which they can be verified (although this might be costly) 2.2. A hierarchy of fairness definitions Several definitions of fairness have been proposed [1, 7, 16]. The most prominent definition is the one by Asokan [1] in which he distinguishes between strong and weak fairness. For weak fairness it is required that in case of a failed exchange either party can prove that it has behaved correctly, i.e. it has followed the prescribed exchange ....

....5a or I 5b i This is a very efficient optimistic fair exchange protocol providing fairness F 6 , which will be elaborated on at the end of this section. P 7 : hI 1a ; I 2a ; I 4a ; external disputei This is an alternative implementation for the active protocol P 1 . The NetBill payment protocol [16] uses a similar idea to ensure fairness. P 8 : hI 1a ; I 2a ; I 5a or I 5b i This protocol is also a variation of the active protocol P 1 . The protocols P 1 , P 2 , P 4 , and P 7 correspond to the existing protocols cited in the short protocol descriptions given above. The other protocols are ....

J. D. Tygar. Atomicity in electronic commerce. In Proceedings of the 15th Annual ACM Symposium on Principles of Distributed Computing (PODC'96), pages 8--26, New York, May 1996. ACM.

....at the highest level, in terms of how the behaviors and relationships between these components contribute to the progress of an e commerce (business) transaction. Speci cally, the property, or goal, of the e commerce system is that (the right) goods be exchanged for (the correct amount of) money [9]. In e commerce, as in most real systems, this end to end property must hold in spite of failures; in other words, once the merchant con rms and order to a client, the goal of completing the exchange of goods for money must be attained eventually. Throughout the paper, we consider the speci c ....

....actions will occur. 2.4. End to end Correctness Properties Besides using our framework to show how component systems deliver their guaranteed properties, we can also use it to reason about the correctness properties of the toplevel system. In particular we are interested in MoneyGoods Atomicity [9]. For example, we can show for the E commerce system that # the correct exchange of goods for money is guaranteed. That is, no one loses or gains in the process (in this scenario, to keep things simple, we do not model pro ts, commissions, etc. the Customer pays money for goods, the Supplier ....

J. D. Tygar. Atomicity in electronic commerce. In Proc. of the 15th Annual ACM Symposium on Principle of Distributed Computing, pages 826, May 1996.

....between two groups of high level properties: 1. properties of a broader class of systems (e.g. electronic commerce in general) An example of an electronic commerce property (we term it EC invariant) is that goods be exchanged for money. Figure 2 lists some common invariants, described by Tygar [Tyg96] as forms of atomicity. 2. Properties specific to the system under consideration (e.g. the web auction scenario) An example of a system specific property is the expectation that the highest bidder in an auction will get the item being auctioned. 9 property description example Money ....

....conducting an auction expects that if there is at least one bid on the item, the item will sell and the Arbiter will collect a commission from the Seller. Proving that the Arbiter will collect commission is analogous to Seller property (1) above. 3. 5 General Electronic Commerce Properties Tygar [Tyg96] identifies system wide high level properties that are desirable for all Electronic Commerce situations; we call them invariants. These are three kinds of invariants, as summarized in Figure 2. Here we briefly indicate how these Electronic Commerce properties relate to the high level properties ....

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J. D. Tygar. Atomicity in electronic commerce. In Proc. of the 15th Annual ACM Symposium on Principle of Distributed Computing, pages 8--26, May 1996.

..... Authentication, privacy and anonymity of participants . secrecy of bids and strategies . controllable revelation of information about the auction including the nal result 2 . the atomicity of the goods and charge (i.e. a winner only needs to pay if he gets the goods or vice versa) [21, 2]. authentication by participants and stakeholders that any given auction actually followed the above rules. Prior to our work, no solution satised this wide variety of security requirements. A main disadvantage of most of the existing auction schemes is that they require the sellers and ....

J. D. Tygar. Atomicity in electronic commerce. In Proc. 15th ACM Symposium on Principles of Distributed Computing (PODC), pages 8--26, 1996.

.... Authentication, privacy and anonymity of participants secrecy of bids and strategies controllable revelation of information about the auction including the final result 2 the atomicity of the goods and charge (i.e. a winner only needs to pay if he gets the goods or vice versa) [20, 3]. authentication by participants and stakeholders that any given auction actually followed the above rules. Prior to our work, no solution satisfied this wide variety of security requirements. A main disadvantage of most of the existing auction schemes is that they require the sellers and ....

J. D. Tygar. Atomicity in electronic commerce. In Proc. 15th ACM Symposium on Principles of Distributed Computing (PODC), pages 8--26, 1996.

....with correctly and reliably carrying out protocol steps that are decisive 3 to guaranteeing satisfaction of a targeted property. For example, trusted parties are entrusted with generating fresh keys in authentication protocols to guarantee authentication [71, 74, 81] In some payment protocols [84], they are entrusted with implementing transaction processing [66] to achieve fairness. This notion of trust is a refinement of the definition of trust adopted by the US Department of Defense in the context of secure systems, which states that a trusted component is one which, if it breaks, can ....

....distinguish them from our work. 1.6.1 Atomicity, Fairness, and Related Properties Protection of individuals interests is a generalization of fairness, and fairness is closely related to atomicity. An introduction to fairness appears in Section 1.2; we do not repeat it here. As for 8 atomicity [84], there are three levels of atomicity. Money atomic protocols transfer funds from one party to another without creating or destroying money. Goods atomic protocols are money atomic, and guarantee that goods are delivered if and only if money is transferred. Finally, certified delivery protocols ....

[Article contains additional citation context not shown here]

J. D. Tygar. Atomicity in electronic commerce. In Proceedings of the Fifteenth Annual ACM Symposium on Principles of Distributed Computing, pages 8--26, May 1996.

No context found.

J. D. Tygar. Atomicity in electronic commerce. In Proceedings of the 15th Annual ACM Symposium on Principles of Distributed Computing (PODC '96), pages 8--26, Philadelphia, PA, May 1996. ACM Press.

No context found.

J. D. Tygar. Atomicity in electronic commerce. In Proceedings of the 15th Annual ACM Symposium on Principles of Distributed Computing (PODC '96), pages 8--26, Philadelphia, PA, May 1996. ACM Press.

No context found.

Tygar, J., "Atomicity in Electronic Commerce", Proc. of ACM Symposium on Principles of Distributed Computing, May 23-26, 1996.

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Tygar, J. D. (1996) Atomicity in electronic commerce. Proceedings of the 15th Annual ACM Symposium on Principles of Distributed Computing (PODC '96), Philadelphia, PA, May, pp. 8--26, ACM Press, New York.

No context found.

J. D. Tygar. Atomicity in electronic commerce. In Proceedings of the 15th Annual ACM Symposium on Principles of Distributed Computing (PODC'96), pages 8-26, New York, May 1996. ACM.

No context found.

Tygar, J. D. (1996) Atomicity in electronic commerce. In Proc. 15th Ann. ACM Symp. on Principles of Distributed Computing (PODC '96), Philadelphia, PA, May, pp. 8--26. ACM Press, New York.

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J. D. Tygar "Atomicity in electronic commerce", Proceedings of the Fifteenth Annual ACM Symposium on Principles of Distributed Computing, Philadelphia, PA, USA, 23-26 May 1996.

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J. D. Tygar. Atomicity in electronic commerce. In Proceedings of the 15th Annual ACM Symposium on Principles of Distributed Computing (PODC '96), pages 8--26, Philadelphia, PA, May 1996. ACM Press.

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Tygar, J.D., Atomicity in Electronic Commerce, ACM-Mixed Media, 1998

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