Jacob Löfvenberg

Learn More
Thresholds for sensation of continuous sinusoidal skin displacements were determined in 7 different test points in the glabrous skin area of the right hand of 11 human subjects. While the subjects were tracking the threshold, the frequency of the sine wave was continuously varied between 0.8 Hz and 400 Hz. THe obtained threshold-frequency functions showed(More)
A new approach to low redundancy coding for reducing power dissipation in parallel on-chip, deep sub-micron buses is presented. It is shown that the new approach allows lower power dissipation than previous solutions in the given model, yielding reductions of 24% to 41% compared to uncoded transmission for the considered bus widths. Finally some important(More)
Unlicensed, or illegal, copying of data is a problem in many areas. Despite various efforts in copy protection and copyright enforcement (both legal and technical), the problem still exists, and with the growing use of digital means of storing and distributing data the problem seems to be getting worse. Storing a unique, invisible marking in each(More)
Traceability codes are identifiable parent property (IPP) codes with the additional requirement that Hamming distance can be used to trace a parent of a word. Traceability codes can be used for constructing digital fingerprints in order to deter users from illegally copying digital data. We construct a class of traceability codes and determine the exact(More)
In this paper we present a simplified model of parallel, on-chip buses, motivated by the movement toward CMOS technologies where the ratio between interwire capacitance and wire-to-ground capacitance is very large. We also introduce a ternary bus state representation, suitable for the bus model. Using this representation we propose a coding scheme without(More)
Coding methods for fingerprinting digital information are considered, with the aim of deterring users from copyright violation. A general model for discrete fingerprinting is presented, along with a simple embedding method for text documents. Different types of attacks are discussed, including attacks from colluding pirates. Some preliminary results are(More)
We consider the broadcast encryption problem where one sender wishes to transmit messages securely to a selected set of receivers using a broadcast channel, as is the case in digital television for example. Specifically, we study the subset difference scheme for broadcast encryption and the number of broadcast transmissions required when using this scheme.(More)
In this paper we consider the subset difference scheme for broadcast encryption and count the number of required broadcast transmissions when using this scheme. The subset difference scheme organizes receivers in a tree structure and we note that isomorphic trees yield the same number of required broadcast transmissions. Based on the isomorphism the trees(More)