Scan technology carries the potential risk of being misused as a “side channel” to leak out the secrets of crypto cores. The existing scan-based attacks could be viewed as one kind of differential cryptanalysis, which takes advantages of scan chains to observe the bit changes between pairs of chosen plaintexts so as to identify the secret keys. To address such a design/test challenge, this paper proposes a robust secure scan structure design for crypto cores as a countermeasure against scan-based attacks to maintain high security without compromising the testability.

Scan-based attacks are techniques to decipher a secret key using scanned data obtained from a cryptography circuit. Public-key cryptography, such as RSA and elliptic curve cryptosystem (ECC), is extensively used but conventional scan-based attacks cannot be applied to it, because it has a complicated algorithm as well as a complicated architecture. This paper proposes a scan-based attack which enables us to decipher a secret key in ECC. The proposed method is based on detecting intermediate values calculated in ECC. By monitoring the 1-bit sequence in the scan path, we can find out the register position specific to the intermediate value in it and we can know whether this intermediate value is calculated or not in the target ECC circuit. By using several intermediate values, we can decipher a secret key. The experimental results demonstrate that a secret key in a practical ECC circuit can be deciphered using 29 points over the elliptic curve E within 40 seconds.

Scan test is a powerful and popular test technique because it can control and observe the internal states of the circuit under test. However, scan path would be used to discover the internals of crypto hardware, which presents a significant security risk of information leakage. An interesting design-for-test technique by inserting inverters into the internal scan path to complicate the scan structure has been recently presented. Unfortunately, it still carries the potential of being attacked through statistical analysis of the information scanned out from chips. Therefore, in this paper we propose secure scan architecture, called dynamic variable secure scan, against scan-based side channel attack. The modified scan flip-flops are state-dependent, which could cause the output of each State-dependent Scan FF to be inverted or not so as to make it more difficult to discover the internal scan architecture.

In this paper, we propose a high-level synthesis method targeting generalized distributed-register architecture in which we introduce shared/local registers and global/local controllers. Functional units on a critical path use local registers and local controllers and functional units on non-critical path use shared register and global controller in our architecture. Our method is based on iterative improvement of scheduling/binding and floorplanning. Using iterative flow, we obtains a generalized distributed-register architecture where its scheduling/binding as well as floorplanning are simultaneously optimized. Experimental results show that 8.6% performance improvement can be achieved compared to the conventional high-performance method.

Due to the limitations of scan structure, the second vector in transition delay test is usually applied either by shift operation or by functional launch, which possibly results in unsatisfying transition delay fault (TDF) coverage. To overcome such a limitation for higher TDF coverage, a novel improved launch delay test technique that combines the pros of launch-on-shift and launch-on-capture tests is introduced in this paper. The proposed method can achieve near perfect TDF coverage with fewer test patterns without the need for a global fast scan enable signal. Experimental results on ISCAS89 and ITC99 benchmark circuits are included to show the effectiveness of the proposed method.

In recent years, the gap between the cycle time of processors and memory access time has been increasing. One of the solutions to solve this problem is to use a cache. But just using a large cache may not reduce the total memory access time. We can have an optimal cache configuration which minimizes overall memory access time by varying the three cache parameters: a cache set size, a line size, and an associativity. In this paper, we propose two exact cache simulation algorithms: CRCB1 and CRCB2, based on cache inclusion property. They realize exact cache simulation but increase simulation speed dramatically. By using our approach, the number of cache hit/miss judgments required for simulating all the cache configurations is reduced to 31.4% - 93.6% compared to conventional approaches. As a result, our proposed approach totally runs an average of 1.8 times faster and a maximum of 3.3 times faster compared to the fastest approach proposed so far. Our proposed exact cache simulation approach achieves the world fastest L1 cache simulation.

Scan technology carries the potential of being misused as a ¿side channel¿ to leak out the secret information of crypto cores. To address such a design challenge, this paper proposes a design-for-secure-test (DFST) solution for crypto cores by adding a stimuli-launched flip-flop into the traditional scan flip-flop to maintain the high test quality without compromising the security.

This paper introduces GECOM technology, a novel test compression method with seamless integration of test GEneration, test COmpression (i.e. integrated compression on scan stimulus and masking bits) and all unknown scan responses Masking for manufacturing test cost reduction. Unlike most of prior methods, the proposed method considers the unknown responses during ATPG procedure and selectively encodes the specified 1 or 0 bits (either is or Os) in scan slices for compression while at the same time masks the unknown responses before sending them to the response compactor. The proposed GECOM technology consists of GECOM architecture and GECOM ATPG technique. In the GECOM architecture, for a circuit with N internal scan chains, only c tester channels, where c = [log2N] +2, are required. GECOM ATPG generates test patterns for the GECOM architecture thus not only the scan inputs could be efficiently compressed but also all the unknown responses would be masked. Experimental results on both benchmark circuits and real industrial designs indicated the effectiveness of the proposed GECOM technique.

Modular multiplication is the most dominant arithmetic operation in elliptic curve cryptography (ECC), which is a type of public-key cryptography. Montgomery multiplication is commonly used as a technique for the modular multiplication and required scalability since the bit length of operands varies depending on the security levels. Also, ECC is performed in GF(P) or GF(2n), and unified architectures for GF(P) and GF(2n) multiplier are needed. However, in previous works, changing frequency or dual-radix architecture is necessary to deal with delay-time difference between GF(P) and GF(2n) circuits of the multiplier because the critical path of GF(P) circuit is longer. This paper proposes a scalable unified dual-radix architecture for Montgomery multiplication in GF(P) and GF(2n). The proposed architecture unifies 4 parallel radix-216multipliers in GF(P) and a radix-264multiplier in GF(2n) into a single unit. Applying lower radix to GF(P) multiplier shortens its critical path and makes it possible to compute the operands in the two fields using the same multiplier at the same frequency so that clock dividers to deal with the delay-time difference are not required. Moreover, parallel architecture in GF(P) reduces the clock cycles increased by dual-radix approach. Consequently, the proposed architecture achieves to compute GF(P) 256-bit Montgomery multiplication in 0.23 mus.

Cryptography plays an important role in the security of data transmission. To ensure the correctness of crypto hardware, we should conduct testing at fabrication and infield. However, the state-of-the-art scan-based test techniques, to achieve high test qualities, need to increase the testability of the circuit under test, which carries a potential of being misused to reveal the secret information of the crypto hardware. Thus, to develop efficient test strategies for crypto hardware to achieve high test quality without compromising security becomes an important task. In this paper we discuss the development of a design-for-secure-test (DFST) technique for pipelined AES to overcome the above contradiction between security and test quality in testing crypto hardware. Unlike previous works, the proposed method can keep all the secrets inside and provide high test quality and fault diagnosis ability as well. Furthermore, the proposed DFST technique can significantly reduce test application time, test data volume, and test generation effort as additional benefits.

In SoC designs, efficient communication between the hardware IPs and the on-chip processor becomes very important; however the interface is usually affected by the processor core specification. Thus in this paper, we focus on developing an efficient interface circuit architecture for the communications between the on-chip processor and embedded hardware IP cores, we also propose a method to synthesize it. Experimental results show that our method could obtain optimal interface circuits and works well through designing a MPEG-4 encode application.

This paper proposes a new multiscan-based test input data compression technique by employing a fan-out compression scan architecture (FCSCAN) for test cost reduction. The basic idea of FCSCAN is to target the minority specified 1 or 0 bits (either 1 or 0) in scan slices for compression. Due to the low specified bit density in test cube set, FCSCAN can significantly reduce input test data volume and the number of required test channels so as to reduce test cost. The FCSCAN technique is easy to be implemented with small hardware overhead and does not need any special ATPG for test generation. In addition, based on the theoretical compression efficiency analysis, improved procedures are also proposed for the FCSCAN to achieve further compression. Experimental results on both benchmark circuits and one real industrial design indicate that drastic reduction in test cost can be indeed achieved.

This paper proposes a new design methodology for SoCs reusing hardware IPs. In our approach, after system-level HW/SW partitioning, we use IPs for hardware parts, but synthesize a new processor core instead of reusing a processor core IP. System performs efficient parallel execution of hardware and software by taking account of a response time of hardware IP obtained by the proposed calculation algorithm. We can use optimal hardware IPs selected by the proposed hardware IPs selection algorithm. The experimental results show effectiveness of our new design methodology.

This paper presents a new DFT technique that can significantly reduce test data volume as well as scan-in power consumption for multiscan-based designs. It can also help to reduce test time and tester channel requirements with small hardware overhead. In the proposed approach, we start with a pre-computed test cube set and fill the don’t-cares with proper values for joint reduction of test data volume and scan power consumption. In addition we explore the linear dependencies of the scan chains to construct a fanout structure only with inverters to achieve further compression. Experimental results for the larger ISCAS’89 benchmarks show the efficiency of the proposed technique.

Test data volume and scan power are two major concerns in SoC test. In this paper we present an alternative run-length coding method through scan chain reconfiguration to reduce both test data volume and scan-in power consumption. The proposed method analyzes the compatibility of the internal scan cells for a given test set and then divides the scan cells into compatible classes. To extract the compatible scan cells we apply a heuristic algorithm by solving the graph coloring problem; and then a simple greedy algorithm is used to configure the scan chain for the minimization of scan power. Experimental results for the larger ISCAS'89 benchmarks show that the proposed approach leads to highly reduced test data volume with significant power savings during scan test.

This paper proposes a new hardware/software partitioning algorithm for processor cores with SIMD instructions. Given a compiled assembly code including SIMD instructions, a timing constraint of execution time, and available hardware units, the proposed algorithm synthesizes an area-optimized processor core with a new assembly code. Firstly, we assume an initial processor core on which an input assembly code can run with the shortest execution time. Secondly we reduce a hardware unit added to a processor core one by one while the timing constraint is satisfied. At the same time, we update the assembly code so that it can run on the new processor configuration. By repeating this process, we finally obtain a processor core architecture with small area under the given timing constraint. We expect that we can obtain a processor core which has appropriate SIMD functional units for running the input application program. The promising experimental results are also shown.

Hardware/software partitioning is one of the key processes in a hardware/software cosynthesis system for digital signal processor cores. In hardware/software partitioning, area and delay estimation of a processor core plays an important role since the hardware/software partitioning process must determine which part of a processor core should be realized by hardware units and which part should be realized by a sequence of instructions based on execution time of an input application program and area of a synthesized processor core. This paper proposes area and delay estimation equations for digital signal processor cores. For area estimation, we show that total area for a processor core can be derived from the sum of area for a processor kernel and area for additional hardware units. Area for processor kernel can be mainly obtained by minimum area for processor kernel and overheads for adding hardware units and registers. Area for a hardware unit can be mainly obtained by its type and operation bit width. For delay estimation, we show that critical path delay for a processor core can be derived from the delay of a hardware unit which is on the critical path in the processor core. Experimental results demonstrate that errors of area estimation are less than 2% and errors of delay estimation are less than 2ns when comparing estimated area and delay with logic-synthesized area and delay.

Article Free Access Share on An area/time optimizing algorithm in high-level synthesis for control-based hardwares (short paper) Authors: Nozomu Togawa Dept. of Electronics, Information and Communication Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan Dept. of Electronics, Information and Communication Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, JapanView Profile , Masayuki Ienaga Dept. of Electronics, Information and Communication Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan Dept. of Electronics, Information and Communication Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, JapanView Profile , Masao Yanagisawa Dept. of Electronics, Information and Communication Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan Dept. of Electronics, Information and Communication Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, JapanView Profile , Tatsuo Ohtsuki Dept. of Electronics, Information and Communication Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan Dept. of Electronics, Information and Communication Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, JapanView Profile Authors Info & Claims ASP-DAC '00: Proceedings of the 2000 Asia and South Pacific Design Automation ConferenceJanuary 2000 Pages 309–312https://doi.org/10.1145/368434.368652Online:28 January 2000Publication History 2citation93DownloadsMetricsTotal Citations2Total Downloads93Last 12 Months1Last 6 weeks0 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

A hardware/software cosynthesis system for processor cores of digital signal processing has been developed. This paper focuses on a hardware/software partitioning algorithm which is one of the key issues in the system. Given an input assembly code generated by the compiler in the system, the proposed hardware/software partitioning algorithm first determines the types and the numbers of required hardware units, such as multiple functional units, hardware loop units, and particular addressing units, for a processor core (initial resource allocation). Second, the hardware units determined at initial resource allocation are reduced one by one while the assembly code meets a given timing constraint (configuration of a processor core). The execution time of the assembly code becomes longer but the hardware costs for a processor core to execute it becomes smaller. Finally, it outputs an optimized assembly code and a processor configuration. Experimental results demonstrate that the system synthesizes processor cores effectively according to the features of an application program/data.

This paper proposes a high-level synthesis system for datapath design of digital signal processing hardwares. The system consists of four phases: (1) DFG (data-flow graph) generation, (2) scheduling, (3) resource binding, and (4) HDL (hardware description language) generation. In (1), the system does not generate only one best DFG representing a given behavioral description of a hardware, but more than one good DFGs representing it. In (2) and (3), several synthesis tools can be incorporated into the system depending on the required objectives. Thus we can obtain more than one datapath candidates for a behavioral description with their area and performance evaluation. In (4), the best datapath design is selected among those candidates and its hardware description is generated. The experimental results for applying the system to several benchmarks show the effectiveness and efficiency.

Rapid system prototyping is one of the main applications for field-programmable gate arrays (FPGAs). At the stage of rapid system prototyping, design specifications can often be changed since they cannot always be determined completely. In this paper, layout design change is focused on and a layout reconfiguration algorithm is proposed for FPGAs. In layout reconfiguration, the main problem is to add LUTs to initial layouts. Our algorithm consists of two steps: For given placement and global routing of LUTs, Step 1 places an added LUT with allowing that the position of the added LUT may overlap that of a preplaced LUT; Then Step 2 moves preplaced LUTs to their adjacent positions so that the overlap of the LUT positions can be resolved. Global routes are updated corresponding to reconfiguration of placement. The algorithm keeps routing congestion small by evaluating global routes directly both in Steps 1 and 2. Especially in Step 2, if the minimum number of preplaced LUTs are moved to their adjacent positions, our algorithm minimizes routing congestion. Experimental results demonstrate the effectiveness and efficiency of the algorithm.

A new field programmable gate array (FPGA) design algorithm, Maple-opt, is proposed for technology mapping, placement, and global routing subject to a given upper bound of critical signal path delay. The basic procedure of Maple-opt is viewed as top-down hierarchical bipartition of a layout region. In each bipartitioning step, technology mapping onto logic blocks of FPGAs, their placement, and global routing are determined simultaneously, which leads to a more congestion-balanced layout for routing. In addition, Maple-opt is capable of estimating a lower bound of the delay for a constrained path and of extracting critical paths based on the difference between the lower bounds and given constraint values in each bipartitioning step. Two delay-reduction procedures for the critical paths are applied; routing delay reduction and logic-block delay reduction. The routing delay reduction is done by assigning each constrained path to a single subregion when bipartitioning a region. The logic-block delay reduction is done by mapping each constrained path onto a smaller number of logic blocks. Experimental results for benchmark circuits demonstrate that Maple-opt reduces the maximum number of tracks per channel by a maximum of 38% compared with existing algorithms while satisfying almost all the path delay constraints.

In the layout design of transport-processing FPGAs, it is not only required that routing congestion be kept small but also that circuits implemented on them should operate with higher operation frequency. This paper extends the proposed simultaneous placement and global routing algorithm for transport-processing FPGAs, whose objective is to minimize the routing congestion, and proposes a new algorithm, in which the length of each critical signal path (path length) is limited within a specified upper bound imposed on it (path length constraint). The algorithm is based on the hierarchical bipartitioning of the layout regions and LUT (lookup table) sets that are to be placed. Each bipartitioning procedure consists of three phases: (1) estimation of path lengths, (2) bipartitioning of a set of terminals, and (3) bipartitioning of a set of LUTs. After searching the paths with tighter path length constraints by estimating the path lengths in (1), phases (2) and (3) are executed so that their path lengths are reduced with higher priority, and thus path length constraints are not violated. The algorithm has been implemented and applied to transport-processing circuits and compared with conventional approaches. The results demonstrate that the algorithm resolves path length constraints for 11 out of 13 circuits, though it increases the routing congestion by an average of 20%. After detailed routing, it achieves 100% routing for all the circuits and reduces the circuit delay by an average of 23%.

No abstract available.

Technology mapping algorithms for LUT (Look Up Table) based FPGAs have been proposed to transfer a Boolean network into logic-blocks. However, since those algorithms take no layout information into account, they do not always lead to excellent results. In this paper, a simultaneous technology mapping, placement and global routing algorithm for FPGAs, Maple, is presented. Mapleis an extended version of a simultaneous placement and global routing algorithm for FPGAs, which is based on recursive partition of layout regions and block sets. Maple inherits its basic processes and executes the technology mapping simultaneously in each recursive process. Therefore, the mapping can be done with the placement and global routing information. Experimental results for some benchmark circuits demonstrate its efficiency and effectiveness.

An FPGA layout algorithm is presented, which deals with placement and global routing simultaneously by fully exploiting its regular structure. It is based on a simple and fast top-down hierarchical bi-partitioning, with placement and global routes represented by positions of logic-blocks and pseudo-blocks, respectively. Experimental results for several benchmark circuits demonstrates its efficiency and effectiveness.>

A one-dimensional compaction method for layout patterns including rectilinear macrocells on any number of layers is presented. The algorithm is based on the shortest path search on a constraint graph. It generates an optimal layout pattern in the smallest area by introducing effective jogs in O (N log N) time, where N is the number of line segments of the input pattern and inserted jogs. The jogs are inserted by means of an enhanced plane-sweep method developed in the field of computational geometry. Performance data of an experimental program show its efficiency.>

A new gridless router accelerated by Content Addressable Memory (CAM) is presented. A gridless version of the line-expansion algorithm is implemented, which always finds a path if one exists. The router runs in linear time by means of the CAM-based accelerator. Experimental results show that the more obstacles there are in the routing region, the more effective the CAM-based approach is.

The current status of VLSI layout and directions for future research are addressed, with emphasis on the authors' own work. Necessary terminology and definitions and, whenever possible, a precise formulation of the problems are provided. Placement and floorplanning for both the sea-of-gates and building-block designs are examined. The former emphasizes the connectivity specification, whereas the latter must also consider module shape and size. Global routing based on a method of successive cuts on a chip is discussed. This is a hierarchical top-down approach that is useful for both of the above designs. A two-dimensional detailed routing problem and the rip-up and rerouting problem are also discussed. The field of computational geometry and its application to layout-in particular, to gridless routing and compaction-are reviewed, and layout engines are considered.>

This paper presents a new parallel-processing architecture for hardware routers based on the Lee algorithm. Unlike the existing machines, which require N/sup 2/ processors to implement the Lee algorithm on an N x N grid plane, the proposed architecture requires only O(N) processors to find a path in O(N) time. A prototype machine with 64 processors has been developed to deal with a 128 x 128 grid plane. The architecture of the machine is discussed, together with its experimental performance data. Further, it is reported that the parallel-processed Lee algorithm is most useful and powerful when applied to interactive rip-up and reroute.

This paper gives a graph-theoretic approach to the design of one-dimensional logic gate arrays using MOS or I/sup 2/L units. The incidence relation between gates and nets is represented by a graph H = (V, E), and a possible layout of gates and nets is characterized by an interval graph H = (V,E O F), where F is called an augmentation. It is shown that the number of tracks required for between-gate wiring is equal to the clique number (chromatic number) of H, and hence the optimum placement problem is converted to that of minimum clique number augmentation. This turns out to be an NP-complete problem. Instead a polynomial-time algorithm for finding a minimal augmentation is presented, where an augmentation is minimal if no proper subset of it is an augmentation. An algorithm for gate sequencing with respect to a given augmentation is also presented.

This paper gives a graph-theoretic approach to the problem of finding an optimal ordering for Gaussian elimination on a sparse matrix. A set of new “fill-ins” produced by Gaussian elimination on a matrix A is characterized by a triangulation induced by vertex elimination on a graph associated with A. A triangulation T is minimal (minimum) if there exists no triangulation $\hat T$ such that $\hat{T} \subset \subset T(|\hat{T}| < |T|)$, where $ \subset \subset $ denotes the strict inclusion, and an ordering $\alpha $ is optimal (optimum) if a minimal (minimum) triangulation is generated by a. An optimum ordering is necessarily optimal but not conversely. An efficient algorithm for finding an optimal ordering in $O(M \cdot N)$ time is presented, where M is the number of vertices and N is the number of edges of the graph being considered.