On Renyi Entropies and their Applications to Guessing Attacks in Cryptography

We consider single and multiple attacker scenarios in guessing and obtain bounds on various success parameters in terms of Renyi entropies. We also obtain a new derivation of the union bound

Graph Based Framework for Malicious Insider Threat Detection

While most security projects have focused on fending off attacks coming from outside the organizational boundaries, a real threat has arisen from the people who are inside those perimeter protections. \ Insider threats have shown their power by hugely affecting national security, financial stability, and the privacy of many thousands of people. What is in the news is the tip of the iceberg, with much more going on under the radar, and some threats never being detected. We propose a hybrid framework based on graphical analysis and anomaly detection approaches, to combat this severe cyber security threat. Our framework analyzes heterogeneous data in isolating possible malicious users hiding behind others. Empirical results reveal this framework to be effective in distinguishing the majority of users who demonstrate typical behavior from the minority of users who show suspicious behavior.

Differentiation induction in acute promyelocytic leukemia

Hematopoiesis or blood cell formation is a continuous process in which maturing hematopoietic cells with a limited life span are formed. The formation of all different blood cell lineages originates from a small population of pluripotent stem cells that reside in the bone marrow. Progenitor cells that are committed to a certain lineage of differentiation orginate from these pluripotent stem cells. Hematopoiesis is regulated by a network of cytokines and hematopoietic growth factors (HGF). The HGFs are produced locally by stromal cells. mature blood cells, endothelial cells or specialized cells in organs such as lungs, liver and kidney. The levels of HGFs are elevated in response to extracellular stimuli, such as infection or bleeding, when a rapid rise of specific blood cell types is necessary. HGFs exert their effect by binding to their corresponding receptors expressed on the membrane of their target cells. Ligand binding results in the activation of downstream signaling pathways. A cascade of phosphorylation events is involved in signal transduction. In one pathway, the JAK Uanus kinase) family of protein tyrosine kinases are tyrosine phosphorylated and in turn activate a family of latent cytoplasmic transcription factors, called STAT (Signal Transduction and Activation of Transcription) proteins. Following their activation, these STAT proteins are assembled into complexes which then translocate to the nucleus and activate target genes by interaction with specific DNA sequences. Another major HGF receptor signal transduction pathway includes proteins that belong to the Ras family. Signaling molecules like Shc and Grb2 function as adaptor proteins in this pathway by linking phosphorylated receptors to downstream effectors. Grb2 binds to the activated receptor, and to Sos (Son of sevenless) which after translocation to the plasma membrane activates Ras triggering phosphorylation of Rat. The products of Raf, a serine tyrosine kinase and mitogen activated protein kinases (MAPK) transmit signals for futher transmission to the nucleus. In the nucleus, activation of transcription factors by phosphorylation or other mechanisms results in activation of genes involved in cellular proliferation and differentiation. Apart from affecting transcription, activated Ras results in cyclin D1 activation and stimulates p27kip1 degradation via Rho. Both events positively infiuence cell cycle entry (Figure 1.2)

CDMA over QAM and other Arbitrary Energy Constellations

Welch and Sidelnikov lower bounds on the maximum nontrivial correlations of complex signal sets apply to the constrained case of uniform signal energy and have long been used as a benchmark for testing the merit of signal sets in the design of good CDMA sequence families. Welch's lower bound is generalized here to the arbitrary signal energy case and applied to CDMA over QAM modulation. The generalized lower bound is compared to the original bound and an explicit QAM-CDMA family is constructed.

Lower Bounds on the Maximum Periodic and Aperiodic Correlation of Signal Sets with Arbitrary Energy Distribution

THIS IS AN UPDATED VERSION OF THE ORIGINAL PAPER Welch and Sidelnikov have obtained lower bounds on the maximum nontrivial correlations of complex signal sets constrained to have uniform signal energy. These results have long been used as a benchmark for testing the merit of signal sets, e.g., in the design of good CDMA sequence families. The Welch lower bound is generalized here to allow for arbitrary signal energy for each member of the signal set, with a view towards considering the application of CDMA to QAM signals. The generalized lower bound is compared to the original bound and a bound on their ratio is also derived. An example of a QAM-CDMA sequence family concludes the paper.

State cycles, initialization and the Trivium stream cipher

Trivium is a keystream generator for a binary additive synchronous stream cipher. It was selected in the final portfolio for the Profile 2 category of the eSTREAM project. The keystream generator is constructed using bit- based shift registers. In this paper we present an alternate representation of Trivium using word-based shift registers, with a word size of three bits. This representation is useful for determining cycles of internal state values. Under this representation it is clear that the state space can be partitioned into subspaces and that over some of these subspaces the state update function is effectively linear. The role of the initialization process is critical in ensuring the states used for generating keystream are updated nonlinearly at some point, as the state update function alone does not provide this

Randomness testing and comparison of classical and quantum bit generators

Randomness is crucial to enabling secure and robust communications. Ideally one should harness high entropy physical processes, but this is difficult so pseudorandomness is usually substituted for randomness. We introduce improved complexity randomness tests and use them to judge three pseudorandom bit generators; the AES block cipher (standard, strongly believed to be secure), the Dragon stream cipher (eStream finalist), and the GNU C library function rand(). We also test the output from a quantum random bit generator (QRBG). While the two ciphers can easily be distinguished from the much inferior rand(), the output statistics of the two classical generators are similar to that of the QRBG, and both provide high-quality pseudorandom bits

Randomized Traitor Tracing Algorithms for Broadcast Security

We introduce and analyze a randomized traitor tracing algorithm for broadcast security