Suse Engbers - Academia.edu (original) (raw)

Papers by Suse Engbers

This paper describes the results of an ongoing collaborative project between KPN Research and the... more This paper describes the results of an ongoing collaborative project between KPN Research and the Telematics Institute on multimedia information handling. The focus of the paper is the modelling and retrieval of audiovisual information. The paper presents a general framework for modeling multimedia information (ADMIRE) and discusses the application of this framework to the specific area of soccer video clips. The core of the paper is the integration of feature extraction and concept inference in a general framework for representing audio visual data. The work on feature extraction is built on existing feature extraction algorithms. The work on concept inference introduces a new approach to assigning semantics to collections of features in order to support concept-based retrieval, rather than featurebased retrieval. Finally, the paper describes our experiences with the implementation of the methods and techniques within the ADMIRE framework using a collection of commercially available tools. The latter is done by implementing a soccer video clip annotation and query tool.

Journal of biosciences, 2015

Mammals have three HP1 protein isotypes HP1 beta (CBX1), HP1 alpha (CBX3) and HP1 alpha (CBX5) th... more Mammals have three HP1 protein isotypes HP1 beta (CBX1), HP1 alpha (CBX3) and HP1 alpha (CBX5) that are encoded by the corresponding genes Cbx1, Cbx3 and Cbx5. Recent work has shown that reduction of CBX3 protein in homozygotes for a hypomorphic allele (Cbx3hypo) causes a severe postnatal mortality with around 99 percent of the homozygotes dying before weaning. It is not known what the causes of the postnatal mortality are. Here we show that Cbx3hypo/hypo conceptuses are significantly reduced in size and the placentas exhibit a haplo-insufficiency. Late gestation Cbx3hypo/hypo placentas have reduced mRNA transcripts for genes involved in growth regulation, amino acid and glucose transport. Blood vessels within the Cbx3hypo/hypo placental labyrinth are narrower than wild-type. Newborn Cbx3hypo/hypo pups are hypoglycemic, the livers are depleted of glycogen reserves and there is almost complete loss of stored lipid in brown adipose tissue (BAT). There is a 10-fold reduction in express...

Lecture Notes in Computer Science, 2011

ABSTRACT Traditional techniques of enforcing an access control policy rely on an honest reference... more ABSTRACT Traditional techniques of enforcing an access control policy rely on an honest reference monitor to enforce the policy. However, for applications where the resources are sensitive, the access control policy might also be sensitive. As a result, an honest-but-curious reference monitor would glean some interesting information from the requests that it processes. For example if a requestor in a role psychiatrist is granted access to a document, the patient associated with that document probably has a psychiatric problem. The patient would consider this sensitive in- formation, and she might prefer the honest-but-curious reference monitor to remain oblivious of her mental problem. We present a high level framework for querying and enforcing a role based access control policy that identifies where sensitive information might be disclosed. We then propose a construction which enforces a role based access control policy cryptographically, in such a way that the reference monitor learns as little as possible about the policy. (The reference monitor only learns something from repeated queries). We prove the security of our scheme showing that it works in theory, but that it has a practical drawback. However, the practical drawback is common to all cryptographically enforced access policy schemes. We identify several approaches to mitigate the drawback and conclude by arguing that there is an underlying fundamental problem that cannot be solved. We also show why attribute based encryption techniques do not not solve the problem of enforcing policy by an honest but curious reference monitor.

Lecture Notes in Computer Science, 2004

When outsourcing data to an untrusted database server, the data should be encrypted. When using t... more When outsourcing data to an untrusted database server, the data should be encrypted. When using thin clients or low-bandwidth networks it is best to perform most of the work at the server. In this paper we present a method, inspired by secure multi-party computation, to search efficiently in encrypted data. XML elements are translated to polynomials. A polynomial is split into two parts: a random polynomial for the client and the difference between the original polynomial and the client polynomial for the server. Since the client polynomials are generated by a random sequence generator only the seed has to be stored on the client. In a combined effort of both the server and the client a query can be evaluated without traversing the whole tree and without the server learning anything about the data or the query.

Lecture Notes in Computer Science, 2008

Searchable encryption is a technique that allows a client to store data in encrypted form on a cu... more Searchable encryption is a technique that allows a client to store data in encrypted form on a curious server, such that data can be retrieved while leaking a minimal amount of information to the server. Many searchable encryption schemes have been proposed and proved secure in their own computational model. In this paper we propose a generic model for the

Lecture Notes in Computer Science, 2010

ABSTRACT A hidden vector encryption scheme (HVE) is a derivation of identity-based encryption, wh... more ABSTRACT A hidden vector encryption scheme (HVE) is a derivation of identity-based encryption, where the public key is actually a vector over a certain alphabet. The decryption key is also derived from such a vector, but this one is also allowed to have ``*'' (or wildcard) entries. Decryption is possible as long as these tuples agree on every position except where a ``$\star$'' occurs. These schemes are useful for a variety of applications: they can be used as a building block to construct attribute-based encryption schemes and sophisticated predicate encryption schemes (for e.g. range or subset queries). Another interesting application -- and our main motivation -- is to create searchable encryption schemes that support queries for keywords containing wildcards. Here we construct a new HVE scheme, based on bilinear groups of prime order, which supports vectors over any alphabet. The resulting ciphertext length is equally shorter than existing schemes, depending on a trade-off. The length of the decryption key and the computational complexity of decryption are both constant, unlike existing schemes where these are both dependent on the amount of non-wildcard symbols associated to the decryption key. Our construction hides both the plaintext and public key used for encryption. We prove security in a selective model, under the decision linear assumption.

14th International Workshop on Database and Expert Systems Applications, 2003. Proceedings., 2003

The present paper addresses privacy issues in electronic audio/video content distribution. It int... more The present paper addresses privacy issues in electronic audio/video content distribution. It introduces an identity-based rights distribution and management system that enables users to access content anytime, anywhere, and on any device by means of authorization certificates issued by a content provider. These certificates openly link the identity of the users to the content that they are entitled to access.

ACM Computing Surveys, 2014

We survey the notion of provably secure searchable encryption (SE) by giving a complete and compr... more We survey the notion of provably secure searchable encryption (SE) by giving a complete and comprehensive overview of the two main SE techniques: searchable symmetric encryption (SSE) and public key encryption with keyword search (PEKS). Since the pioneering work of Song, Wagner, and Perrig (IEEE S&P '00), the field of provably secure SE has expanded to the point where we felt that taking stock would provide benefit to the community.

2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2014

Lecture Notes in Computer Science, 2000

Information Systems Security, 2004

Sometimes there is a need to store sensitive data on an untrusted database server. Song, Wagner a... more Sometimes there is a need to store sensitive data on an untrusted database server. Song, Wagner and Perrig have introduced a way to search for the existence of a word in an encrypted textual document. The search speed is linear in the size of the document. It does not scale well for a large database. We have developed a tree search algorithm based on the linear search algorithm that is suitable for XML databases. It is more efficient since it exploits the structure of XML. We have built prototype implementations for both the linear and the tree search case. Experiments show a major improvement in search time.

IEEE Transactions on Systems, Man, and Cybernetics - Part A: Systems and Humans, 2000

Environmental Science & Technology, 2011

Searchable encryption is a technique that allows a client to store documents on a server in encry... more Searchable encryption is a technique that allows a client to store documents on a server in encrypted form. Stored documents can be retrieved selectively while revealing as little information as possible to the server. In the symmetric searchable encryption domain, the storage and the retrieval are performed by the same client. Most conventional searchable encryption schemes suffer from two disadvantages.