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Computers and Digital Techniques, IEE Proceedings -

Issue 5 • Date Sep 1994

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Displaying Results 1 - 10 of 10
  • Interleaving security and efficiency considerations in the design of inexpensive IC cards

    Page(s): 265 - 270
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    Currently used inexpensive IC cards (e.g. payphone cards) prove their authenticity and generate digital signatures by means of a simple circuit which implements a nonlinear one-way transformation. The paper considers possible approaches for the efficient design and fabrication of such a circuit, based on the observation that the circuit does not have to serve any predefined exact process as long as its functioning falls within a wide range of possible allowed behaviours. It is shown how this tolerance in defining the circuit's behaviour can potentially be traded for efficient design and fabrication of the circuit, without necessarily sacrificing security View full abstract»

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  • Montgomery reduction with even modulus

    Page(s): 314 - 316
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (188 KB)  

    The modular multiplication and exponentiation algorithms based on the Montgomery reduction technique require that the modulus be an odd integer. It is shown that, with the help of the Chinese remainder theorem, the Montgomery reduction algorithm can be used to efficiently perform these modular arithmetic operations with respect to an even modulus View full abstract»

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  • Heterogeneous Petri net methodology for the design of complex controllers

    Page(s): 293 - 297
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    A controller design methodology based on Petri nets is developed. The semantics of the method, and the algorithm for the construction of an equivalent finite state machine make use of both synchronous and asynchronous marking graphs giving rise to the name `heterogeneous Petri nets'. The method allows the designer of a controller greater freedom in the use of well structured graphics specifying the controller while the supporting CAD tool ensures an efficient (in the sense of clock-cycle usage) derivation of an equivalent finite state machine View full abstract»

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  • Decoding the (73, 37, 13) quadratic residue code

    Page(s): 253 - 258
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (284 KB)  

    Algebraic approaches to the decoding of the quadratic residue (QR) codes were studied recently. In Reed et. al. (1992), a decoding algorithm was given for the (41, 21, 9) binary QR code. Here, some new more general properties are found for the syndromes of the subclass of binary QR codes of length n = 8m +1. Using these properties, the new theorems needed to decode this subclass of the QR codes are obtained and proved. As an example of the application of these theorems, a new algebraic decoding algorithm for the (73, 37, 13) binary QR code is presented View full abstract»

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  • Group-oriented (t, n) threshold digital signature scheme and digital multisignature

    Page(s): 307 - 313
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    The paper presents group-oriented (t,n) threshold digital signature schemes based on the difficulty of solving the discrete logarithm problem. By employing these schemes, any t out of n users in a group can represent this group to sign the group signature. The size of the group signature and the verification time of the group signature are equivalent to that of an individual digital signature. In other words, the (t, n) threshold signature scheme has the following five properties: (i) any group signature is mutually generated by at least t group members; (ii) the size of the group signature is equivalent to the size of an individual signature; (iii) the signature verification process is simplified because there is only one group public key required; (iv) the group signature can be verified by any outsider; and (v) the group holds the responsibility to the signed message. In addition to the above properties, two of the schemes proposed do not require the assistance of a mutually trusted party. Each member selects its own secret key and the group public key is determined by all group members. Each group member signs a message separately and sends the individual signature to a designated clerk. The clerk validates each individual signature and then combines all individual signatures into a group signature. The (n, n) threshold signature scheme can be easily extended to become a digital multisignature scheme View full abstract»

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  • Chip level fault location using X-algorithm

    Page(s): 259 - 264
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    In board level testing the faults are usually isolated to a field replacement unit (FRU) rather than to a single chip. In this paper a new algorithm, called the X-algorithm, is presented to locate a faulty chip in an FRU. The location patterns (LPs) which contain only one symbol X/X¯ are introduced. The trajectory of the X/X¯ propagation sensitises the faults in the FRU. Based on the test results the LPs can be generated easily. In the X-algorithm the X/X¯ propagation trajectory is analysed so that the faulty chip can be located automatically. Preliminary results show that the algorithm is quite effective, and it may not be necessary to exhaustively simulate with the LPs View full abstract»

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  • Table driven Newton scheme for high precision logarithm generation

    Page(s): 281 - 292
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (624 KB)  

    Based on the Newton method, a table driven iterative scheme is proposed to compute the logarithm function. The proposed scheme provides high performance and high precision and it is implementable with currently available technologies. It is shown, assuming the availability of a parallel multiplier and an adder and the IEEE floating point format, that a computation delay of 12 machine cycles can be obtained with precision of 0.761×2-53 requiring 18432 bytes of read only memory (ROM). Based on performance and look-up table size estimations of other existing schemes also using table driven approaches a speed-up of over 1.5 for the proposed scheme can be obtained View full abstract»

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  • Analysis and improvement of an access control scheme with user authentication

    Page(s): 271 - 273
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    Both user authentication and access control are required for data protection in computer systems. Recently, Ham and Lin proposed an access control scheme with integration of user authentication. In their scheme, the above two functions are combined together to prevent possible security threats between these two protection modules. This paper, argues that there are some redundant information and verification operations in their scheme. A more compact and efficient alternative, with the same security and characteristics, is presented. Also, a batch-type multiple-access request verification is suggested to improve the efficiency of the system and a password updating process is proposed to facilitate the dynamic operations View full abstract»

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  • Load balancing algorithms for an extended hypercube

    Page(s): 298 - 306
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (716 KB)  

    Reduction of the execution time of a job through equitable distribution of work load among the processors in a distributed system is the goal of load balancing. Performance of static and dynamic load balancing algorithms for the extended hypercube, is discussed. Threshold algorithms are very well-known algorithms for dynamic load balancing in distributed systems. An extension of the threshold algorithm, called the multilevel threshold algorithm, has been proposed. The hierarchical interconnection network of the extended hypercube is suitable for implementing the proposed algorithm. The new algorithm has been implemented on a transputer-based system and the performance of the algorithm for an extended hypercube is compared with those for mesh and binary hypercube networks View full abstract»

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  • Transient analysis and hazard-free design of exclusive-OR switching networks

    Page(s): 274 - 280
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    Transient analysis for exclusive-OR switching networks is studied. Based on the theorems proved for logic hazards, three methods are developed for hazard detection. The first is a graphical method that applies to functions of no more than six variables. The second method, which is an extension of the graphical method, can be applied to networks with any number of inputs. The third method is based on the compatibility of the product terms of a modulo-2 sum. Both the second and third methods can be implemented on computers. Three methods for synthesising hazard-free exclusive-OR switching networks are also presented. The first method applies to functions that are hazard-free realisable. In case a hazard-free network is not attainable, a simple disjoint decomposition of the function as hazard-free subnetworks is recommended. In the third method, hazards are suppressed by a secondary network. This method is used only when the first two methods fail. All three methods for hazard-free design can also be implemented on computers View full abstract»

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