A. Perez

Organizing nanoclusters on functionalized surfaces

This letter reports on the synthesis and observation of periodic arrangements of nanometric size gold islands. Samples are produced by deposition of preformed gold clusters on a functionalized graphite surface. The evolution of the cluster organization with artificial defects nature and periodicity is studied experimentally and analyzed in the framework of Kinetic Monte Carlo (KMC) simulations. This study points out the potentialities of the technique to organize nanostructures on patterned surfaces.

AES Implementation on FPGA: Time - Flexibility Tradeoff

This paper presents some FPGA-based implementations of the private key Advanced Encryption Standard (AES) cryptography algorithm. The technological fixed target is one V1000BG560 Xilinx Virtex FPGA. A basic architecture is presented first for a 256-bit Cipher Key and a 256-bit Block configuration. Partially pipelined structures were also implemented and perform a throughput rate proportional to the pipeline degree. These improved architectures can ensure high speed encryption by processing several Blocks of the plaintext concurrently. In return they need more logic resources. The resources being limited to the Virtex device ones, the highest speed implementations will loose flexibility as for the choice of the number of bits coding the Cipher Key or the Blocks. Different implementation results illustrating this time - flexibility tradeoff are presented and commented.

Exploration of the ultimate patterning potential of focused ion beams

We aim to explore the nanostructuring potential of a highly focused pencil of ions. We show that focused ion beam technology (FIB) is capable of overcoming some basic limitations of current nanofabrication techniques and allowing innovative patterning schemes for nanoscience. In this work, we first detail the very high resolution FIB instrument developed specifically to meet nanofabrication requirements. Then we introduce and illustrate some new patterning schemes for next-generation FIB processing. These patterning schemes are: 1. nanoengraving of membranes as a template for nanopores and nanomask fabrication; 2. local defect injection for magnetic thin film direct patterning; 3. function of graphite substrates to prepare 2-D organized arrays of clusters; and 5. selective epitaxy of III-V semiconductors on FIB patterned surfaces. Finally, we show that FIB patterning allows bottom-up or organization processes.

Cluster-assembled materials: a new class of nanostructured materials with original structures and properties

The low energy cluster beam deposition technique (LECBD) is used to produce nanostructured materials with original structures and properties. In this technique, clusters do not fragment upon impact on the substrate leading to the formation of granular films by nearly random stacking of incident clusters. Both nanostructured films and films of clusters embedded in various matrices are produced using this technique. The production and deposition of controlled size distributions of free clusters are briefly described as well as the specific nucleation and growth process characteristic of the LECBD. In the second part of the paper are presented some characteristic examples of novel materials prepared by this technique. The formation and properties of films of covalent materials (C, Si) and metallic materials (Fe, Co, Ni) are presented to emphasize the memory effect of the free cluster structure in the first case and the effect of the nanocrystalline film structure through the magnetic properties in the second case.

Efficient hardware implementation of a CRYPTO-MEMORY based on AES algorithm and SRAM architecture

This paper presents a CRYPTO-MEMORY based on Advanced Encryption Standard (AES) algorithm and SRAM architecture. The design of a dual-port SRAM has been modified by the addition of all logic operators required by the hardware implementation of AES. Moreover, a Finite State Machine has been included in order to allow a self-encryption in full autonomy. Consequently, compared to the classical scheme consisting of a crypto-block and a separated memory, this new design will lead to an important reduction of data transfers during the encryption process. So this will increase the security of sensitive data. This CRYPTO-MEMORY has a storage capacity of 32 k bits and is able to encrypt a 16*128-bit message using a 128-bit key. Its hardware implementation uses 386 k gates and encrypts a 128-bit message in 44 clock cycles.

DES-SRAM IP-core: a SRAM embedding DES feature [secure SoC applications]

This paper proposes a DES-SRAM IP-core dedicated to secure SoCs. This core is an optimized hardware implementation of a DES (data encryption standard) secret key algorithm. The main idea was to implement a DES feature inside a basic SRAM in order to suppress data transfers during data encryption and thus to avoid a bus bottleneck as well as to increase SoC security. The DES capability only adds few percent hardware overhead, and our modified SRAM offers two operating modes: a basic SRAM mode and an encryption mode. The DES-SRAM self-encrypts each 64 bit block of its own data in 17 clock cycles.

Multi-object spectroscopy in space

This paper analyses the various ways of carrying out near IR multi-object spectroscopic studies in space. We show that ground-based observations would have limited results except in the 1-1.5 micrometers wavelength where large telescope of the 8m class would be approximately equivalent to a 1m in space. Beyond 2m, even an instrument such as the adaptive-slit near IR (ANIS) would be much more efficient. Due to their position in space, the traditional masks used in ground- based telescopes cannon be used. New technologies must be developed. Here, we present a multi-object spectrograph called ANIS based on micro-mirror arrays and designed for NGST PathFinder3. It would be able to perform a near IR spectroscopic/photometric mini-survey of the sky over a few square degrees. Thanks to its large field of view, ANIS would be complementary to NGST. Its goal would be to probe the Universe in the 0 < z < 5 range and we can consider ANIS as a scientific precursor for the NGST.