Work Incentives and the Cost of Redistribution via Tax-transfer Reforms under Constrained Labor Supply

Using information on desired and actual hours of work, we formulate a discrete choice model of constrained labor supply. Using the German Socio-Economic Panel and the microsimulation model STSM, we find that hours and participation elasticities are substantially smaller than those in the conventional model. We evaluate two reforms for Germany. Both redistribute to the working poor. The first reform is financed through an increase in the effective marginal tax rate for welfare recipients, the second through an increase in taxes. The first reform is desirable with equal weights, the second if the social planner has substantial redistributive taste

A comparison of PUF cores suitable for FPGA devices

A PUF extracts a unique identifier per die using physical random variation caused by variability of the manufacturing process. PUFs can be used for hardware authentication, but also as generators of confidential keys. This paper presents the comparison of RO-PUF and TERO-PUF cores implemented on Xilinx Spartan 6 FPGA. The objective is to evaluate their design when operating at the same conditions. We show that no ideal PUF exists and therefore designers will always have to choose the PUF matching the security application. In addition to design parameters like area, number of bits per challenge and power consumption, we discuss the feasibility of the design in FPGAs. This will help designers select the best PUF according to their requirements

Platform for Testing and Evaluation of PUF and TRNG Implementations in FPGAs

Implementation of cryptographic primitives like Physical Unclonable Functions (PUFs) and True Random Number Generators (TRNGs) depends significantly on the underlying hardware. Common evaluation boards offered by FPGA vendors are not suitable for a fair benchmarking, since they have different vendor dependent configuration and contain noisy switching power supplies. The proposed hardware platform is primary aimed at testing and evaluation of cryptographic primitives across different FPGA and ASIC families. The modular platform consists of a motherboard and exchangeable daughter board modules. These are designed to be as simple as possible to allow cheap and independent evaluation of cryptographic blocks and namely PUFs. The motherboard is based on the Microsemi SmartFusion 2 SoC FPGA. It features a low-noise power supply, which simplifies evaluation of vulnerability to the side channel attacks. It provides also means of communication between the PC and the daughter module. Available software tools can be easily customized, for example to collect data from the random number generator located in the daughter module and to read it via USB interface. The daughter module can be plugged into the motherboard or connected using an HDMI cable to be placed inside a Faraday cage or a temperature control chamber. The whole platform was designed and optimized to fullfil the European HECTOR project (H2020) requirements

Comparison of Scalable Montgomery Modular Multiplication Implementations Embedded in Reconfigurable Hardware

International audienceThis paper presents a comparison of possible approaches for an efficient implementation of Multiple-word radix-2 Montgomery Modular Multiplication (MM) on modern Field Programmable Gate Arrays (FPGAs). The hardware implementation of MM coprocessor is fully scalable what means that it can be reused in order to generate long-precision results independently on the word length of the originally proposed coprocessor. The first of analyzed implementations uses a data path based on traditionally used redundant carry-save adders, the second one exploits, in scalable designs not yet applied, standard carry-propagate adders with fast carry chain logic. As a control unit and a platform for purely software implementation an embedded soft-core processor Altera NIOS is employed. All implementations use large embedded memory blocks available in recent FPGAs. Speed and logic requirements comparisons are performed on the optimized software and combined hardware-software designs in Altera FPGAs. The issues of targeting a design specifically for a FPGA are considered taking into account the underlying architecture imposed by the target FPGA technology. It is shown that the coprocessors based on carry-save adders and carry-propagate adders provide comparable results in constrained FPGA implementations but in case of carry-propagate logic, the solution requires less embedded memory and provides some additional implementation advantages presented in the paper

An open-source multi-FPGA modular system for fair benchmarking of true random number generators

International audienceTrue Random Number Generators (TRNG) are cryptographic primitives that exploit intrinsic noise sources in electronic devices. Their quality is linked to the underlying technology, activity of the neighboring circuitry and device environment (temperature, power supply, electromagnetic emanations). Consequently, when comparing TRNGs, they should be tested in identical technology, system architecture and operating conditions. We present a unified hardware platform and related open source tools aimed at fair benchmarking of TRNGs implemented in different FPGA technologies. The platform is accessible remotely. Designers can download related tools from the web site and they can upload their configuration bitstream to the remote FPGA and download random data generated in the same hardware and in the same conditions as other concurrent designs and state-of-the-art generators. The proposed tools were approved in many applications and they guarantee safe acquisition of random sequences at data rates of up to 400 Mbits/s

An ultra-lightweight transmitter for contactless rapid identification of embedded IP in FPGA

International audienceThis letter presents the first ultra-lightweight transmitter based on electromagnetic emanation to send embedded intellectual properties (IP) identity (ID) quickly and discreetly. The proposed solution is based on a binary frequency shift keying (BFSK) transmitter that ensures an exceptionally high data rate. In addition, we present a coherent demodulation method using slippery window spectral analysis to recover data outside the device. The hardware resources occupied by the transmitter represent less than 0.022% of a 130 nm Microsemi Fusion FPGA. The experimental bitrate of the data transmission is around 500 times higher than the bitrate available for other state of the art spy circuitry using power consumption. In comparison with other works, our proposal goes clearly towards using a spy circuit in an industrial context for IP protection

A Self-timed Ring Based True Random Number Generator

International audienceSelf-timed rings are oscillators in which several events can evolve evenly-spaced in time thanks to analog effects inherent to the ring stage structure. One of their interesting features is that they provide precise high-speed multiphase signals. This paper presents a true random number generator that exploits the jitter of events propagating in a self-timed ring with a high entropy. Designs implemented in Altera Cyclone III and Xilinx Virtex 5 devices provide high quality random bit sequences passing FIPS 140-1 and NIST SP 800-22 statistical tests at a high bit rate

Secure extension of FPGA general purpose processors for symmetric key cryptography with partial reconfiguration capabilities

International audienceIn data security systems, general purpose processors (GPPs) are often extended by a cryptographic accelerator. The paper presents three ways of extending GPPs for symmetric key cryptography applications. Proposed extensions guarantee secure key storage and management even if the system is facing protocol, software and cache memory attacks. The system is partitioned into processor, cipher, and key memory zones. The three security zones are separated at protocol, system, architecture and physical levels. The proposed principle was validated on Altera NIOS II, Xilinx MicroBlaze and Microsemi Cortex M1 soft core processor extensions. We show that stringent separation of the cipher zone is helpful for partial reconfiguration of the security module, if the enciphering algorithm needs to be dynamically changed. However, the key zone including reconfiguration controller must remain static in order to maintain the high level of security required. We demonstrate that the principle is feasible in partially reconfigurable field programmable gate arrays (FPGAs) such as Altera Stratix V or Xilinx Virtex 6 and also to some extent in FPGAs featuring hardwired general purpose processors such as Cortex M3 in Microsemi SmartFusion FPGA. Although the three GPPs feature different data interfaces, we show that the processors with their extensions reach the required high security level while maintaining partial reconfiguration capability

Implementation of Ring Oscillators Based Physical Unclonable Functions with Independent Bits in the Response

International audienceThe paper analyzes and proposes some enhancements of Ring Oscillators based Physical Unclonable Functions (PUFs). PUFs are used to extract a unique signature of an integrated circuit in order to authenticate a device and/or to generate a key. We show that designers of RO PUFs implemented in FPGAs need a precise control of placement and routing and an appropriate selection of ROs pairs to get independents bits in the PUF response. We provide a method to identify which comparisons are suitable when selecting pairs of ROs. Dealing with power consumption, we propose a simple improvement that reduces the consumption of the PUF published by Suh et al. in 2007 by up to 96.6%. Last but not least, we point out that ring oscillators significantly influence one another and can even be locked. This questions the reliability of the PUF and should be taken into account during the design

Two IP Protection Schemes for Multi-FPGA Systems

International audienceThis paper proposes two novel protection schemes for multi-FPGA systems providing high security of IP designs licensed by IP vendors to system integrators and installed remotely in a hostile environment. In the first scheme, these useful properties are achieved by storing two different configuration keys inside an FPGA, while in the second scheme, they are obtained using a hardware white-box cipher for creating a trusted environment. Thanks to the proposed principles, FPGA configurations coming from different IP owners cannot be cloned or reverse-engineered by any involved party, including system integrator and other IP owners. The proposed schemes can be directly implemented in recent FPGAs such as Xilinx Spartan 6 and Virtex 6