Showing papers on "Message authentication code published in 1986"

Satellite communication system and method with message authentication suitable for use in financial institutions

Abstract: A satellite communications system apparatus and method for authenticating data transmissions uses the position of the transmitter, which position is determined by the satellite communications system. The transmitter position information is appended to the message (which can be either clear text or encrypted), which is sent to the receiver at a second location by the satellite system. A receiver can then authenticate the received message by comparing the received transmitter position with stored transmitter position information. The mobile transceiver syncing versions of the present invention allow the transceiver to be mobile, as opposed to being stationary. In this mobile version, each succeeding message is encrypted using the previous position of the mobile transceiver. Examples of transceivers implementing the apparatus and method of the present invention are shown, as are the specific vertical market applications of financial networks and automatic weather observation and reporting systems. In each version of the present invention, the determination of the location of the transmitter for each message that is received introduces an independently verifiable authentication parameter.

Another Birthday Attack

Abstract: We show that a meet-in-the-middle attack can successfully defraud the Davies-Price message authentication scheme. Their scheme used message blocks in an iterated encipherment of an initial block, and it went through the message blocks twice, in order to prevent just such a "birthday" attack.

Towards a Theory of Software Protection (Extended Abstract)

Abstract: Software protection is one of the most important issues concerning computer practice. The problem is to sell programs that can be executed by the buyer, yet cannot be duplicated and/or distributed by him to other users. There exist many heuristics and ad-hoc methods for protection, but the problem as a whole did not receive the theoretical treatment it deserves.

The practice of authentication

Abstract: One of the most pervasive problems in military and in commercial communications-like systems is the need to authenticate digital messages; where authentication is interpreted broadly to mean verification both that a message was originated by the purported transmitter and that it has not been altered subsequently, which includes verifying that it is not a repetition of an earlier legitimate but already accepted message The terminology ttmessagetl is a carryover from the origins of the problem in communications systems, but as used here includes resident computer software, data bank information, access requests and passes or passwords, hand-shaking exchanges between terminals and central facilities or between card readers and teller machines, etc; ie, digital information exchange over a suspect channel or interface in general The need to authenticate information presupposes an opponent(s) — who may in some circumstances be either the transmitter or receiver — that desires to have unauthentic messages be accepted by the receiver, or by arbiters, as authentic or else to fraudulently attribute to the transmitter messages that he did not send

Designing fault-tolerant algorithms for distributed systems using communication primitives

Abstract: Fault-tolerance is an important requirement in distributed computing systems. However, designing applications for distributed systems is a difficult task, particularly when components of the system can fail. The difficulty of this task increases with the severity of failures encountered. Arbitrary process failures are generally much harder to overcome than failures that are restricted, e.g., where processes only fail by halting. Thus, techniques that restrict the disruptive behavior of faulty processes can greatly simplify the design of fault-tolerant algorithms. Such techniques effectively provide reduction mechanisms from one class of failures to a more benign class. Message authentication is an example of a technique that imposes restrictions on the externally visible behavior of faulty processes. This technique has been used to derive simple solutions to many problems of fault-tolerance for systems with arbitary faults. To exploit the simplicity provided by authentication, we present communication primitives that provide properties of authentication without using digital signatures. These primitives can also be extended to provide properties beyond those of authentication, thereby further restricting the types of faults that have to be overcome. These communication primitives lead to a general methodology for designing fault-tolerant algorithms. We first design an algorithm assuming that messages are signed. Then, replacing signed communication in this algorithm with our broadcast primitive automatically results in an equivalent non-authenticated algorithm. We illustrate this methodology by deriving new solutions to the problems of distributed agreement and clock synchronization in the presence of faults. Our solutions to the problems of Byzantine Agreement, early-stopping Byzantine Agreement, Byzantine Elections, and clock synchronization are simpler and more efficient than those previously known. Furthermore, the clock synchronization algorithm that we propose is the first one that achieves optimal accuracy with respect to real time.