642671
A secure and reliable bootstrap architecture
In a computer system, the integrity of lower layers is typically treated as axiomatic by higher layers. Under the presumption that the hardware comprising the machine (the lowest layer) is valid, the integrity of a layer can be guaranteed if and only if: (1) the integrity of the lower layers is checked and (2) transitions to higher layers occur only after integrity checks on them are complete. The resulting integrity "chain" inductively guarantees system integrity. When these conditions are not met, as they typically are not in the bootstrapping (initialization) of a computer system, no integrity guarantees can be made, yet these guarantees are increasingly important to diverse applications such as Internet commerce, security systems and "active networks". In this paper, we describe the AEGIS architecture for initializing a computer system. It validates integrity at each layer transition in the bootstrap process. AEGIS also includes a recovery process for integrity check failures, and we show how this results in robust systems.
10989722
Practical Problems with a Cryptographic Protection Scheme
Z is a software system designed to provide media-transparent net- work services on a collection of UNIX® machines. These services are comprised of file transfer and command execution; Z preserves file own- ership on remote transfer, and more significantly, owner and group iden- tity when executing commands remotely. In order to secure known vulner- abilities in the system, enhancements were made. In particular, a cryptographically-derived checksum was added to the messages. After the initial implementation of the checksumming scheme, several iterations of performance improvement occurred. The result was unsatisfactory to the user community, so the checksum was removed. Instead, vulnerabilities were reduced by improved monitoring and maintenance procedures.
214797878
The onion technique: indexing for linear optimization queries
This paper describes the Onion technique, a special indexing structure for linear optimization queries. Linear optimization queries ask for top-N records subject to the maximization or minimization of linearly weighted sum of record attribute values. Such query appears in many applications employing linear models and is an effective way to summarize representative cases, such as the top-50 ranked colleges. The Onion indexing is based on a geometric property of convex hull, which guarantees that the optimal value can always be found at one or more of its vertices. The Onion indexing makes use of this property to construct convex hulls in layers with outer layers enclosing inner layers geometrically. A data record is indexed by its layer number or equivalently its depth in the layered convex hull. Queries with linear weightings issued at run time are evaluated from the outmost layer inwards. We show experimentally that the Onion indexing achieves orders of magnitude speedup against sequential linear scan when N is small compared to the cardinality of the set. The Onion technique also enables progressive retrieval, which processes and returns ranked results in a progressive manner. Furthermore, the proposed indexing can be extended into a hierarchical organization of data to accommodate both global and local queries.
33110075
Report of the Purdue Workshop on Grand Challenges in Computer Architecture for the Support of High Performance Computing
Abstract The “Purdue Workshop on Grand Challenges in Computer Architecture for the Support of High Performance Computing” was sponsored by the National Science Foundation to identify critical research topics in computer architecture as they relate to high performance computing. Following a wide-ranging discussion of the computational characteristics and requirements of the grand challenge applications, the workshop identified four major computer architecture grand challenges as crucial to advancing the state of the art of high performance computation in the coming decade. These are: (1) idealized parallel computer models; (2) usable peta-ops (1015 ops) performance; (3) computers in an era of HDTV, gigabyte networks, and visualization; and (4) infrastructure for prototyping architectures. This report overviews some of the demands of the grand challenge applications and presents the above four grand challenges for computer architecture.
12656940
Towards Semantic Universal Multimedia Access
16226748
Polar: an architecture for a parallel ODMG compliant object database
Object database management systems (ODBMS) are now established as the database management technology of choice for a range of challenging data intensiv e applications. Furthermore, the applications associated with object databases typically have stringen t performance requirements, and some are associated with very large data sets. Ho w ever, despite the demands made on object databases by applications, there has been surprisingly little work on parallel object databases. This paper presents the arc hitecture and some preliminary performance results for the Polar ODMG compliant parallel object database. The architecture described has been implemented in a shared-nothing environment on a network of PCs. The paper describes how OQL queries are compiled, parallelized and executed in this environment, and includes some preliminary performance results for OQL queries using the 007 benchmark.
209397857
MPEG-7 Standard for Multimedia Databases.