Generic Architecture and Semiconductor Intellectual Property Cores for Avanced Encryption Standard Cryptography

A generic architecture for implementing the advanced encryption standard (AES) encryption algorithm in silicon is proposed. This allows the instantiation of a wide range of chip specifications, with these taking the form of semiconductor intellectual property (IP) cores. Cores implemented from this architecture can perform both encryption and decryption and support four modes of operation: (i) electronic codebook mode; (ii) output feedback mode; (iii) cipher block chaining mode; and (iv) ciphertext feedback mode. Chip designs can also be generated to cover all three AES key lengths, namely 128 bits, 192 bits and 256 bits. On-the-fly generation of the round keys required during decryption is also possible. The general, flexible and multi-functional nature of the approach described contrasts with previous designs which, to date, have been focused on specific implementations. The presented ideas are demonstrated by implementation in FPGA technology. However, the architecture and IP cores derived from this are easily migratable to other silicon technologies including ASIC and PLD and are capable of covering a wide range of modem communication systems cryptographic requirements. Moreover, the designs produced have a gate count and throughput comparable with or better than the previous one-off solutions.

A framework for assessing the vulnerability of food systems to future shocks

Modem society depends on complex agro-ecological and trading systems to provide food for urban residents, yet there are few tools available to assess whether these systems are vulnerable to future disturbances. We propose a preliminary framework to assess the vulnerability of food systems to future shocks based on landscape ecology's 'Panarchy Framework'. According to Panarchy, ecosystem vulnerability is determined by three generic characteristics: (1) the wealth available in the system, (2) how connected the system is, and (3) how much diversity exists in the system. In this framework, wealthy, non-diverse, tightly connected systems are highly vulnerable. The wealth of food systems can be measured using the approach pioneered by development economists to assess how poverty affects food security. Diversity can be measured using the tools investors use to measure the diversity of investment portfolios to assess financial risk. The connectivity of a system can be evaluated with the tools chemists use to assess the pathways chemicals use to flow through the environment. This approach can lead to better tools for creating policy designed to reduce vulnerability, and can help urban or regional planners identify where food systems are vulnerable to shocks and disturbances that may occur in the future. (c) 2005 Elsevier Ltd. All rights reserved.

THE CORRECTED PRIMARY STRUCTURE OF CHICKEN (AVIAN) PANCREATIC-POLYPEPTIDE

Chicken (avian) pancreatic polypeptide was the first member of the pancreatic polypeptide (PP)/neuropeptide Y (NPY) superfamily to be discovered and structurally-characterised. In this 36 amino acid residue, C-terminally amidated peptide, residues 22 and 23 were identified as Asp and Asn, respectively. However, sequencing of chicken PP using modem automated gas-phase sequencing technology has revealed that the original primary structure is incorrect in that residue 22 is Asn and that residue 23 is Asp. After digestion of chicken PP with endoproteinase Asp-N, fragments of chicken PP corresponding in molecular mass to residues 16-22 and 23-36, were unequivocally identified. The corrected primary structure of chicken PP is therefore: Gly-Pro-Ser-Gln-Pro-Thr-Tyr-Pro-Gly-Asp-Asp-Ala-Pro-Val-Glu-Asp-Leu-Ile-Arg-Phe-Tyr-Asn-Asp-Leu-Gln-Gln-Tyr-Leu-Asn-Val-Val-Thr-Arg-His-Arg-Tyr-NH2.