One of the most frequent operations in modern cryptosystems is a multi-scalar multiplication with two scalars. Common methods to compute it are the Shamir method and the Interleave method whereas their speed mainly depends on the (joint) Hamming weight of the scalars. To increase the speed, the scalars are usually deployed using some general representation which provides a lower (joint) Hamming...

This paper introduces a new privacy filter adopted in the context of the DPT (Drone Protect Task) at MediaEval Benchmark 2015. Our proposed filter protects privacy by visually replacing sensitive RofI (Regions of Interest) by its shapes. A combination of steganography and scrambling is used in order to make this filter. Once the scrambling is applied on the pixels of the RofI, its MSB (Most Sig...

The central topic of this paper is the alternating greedy expansion of integers, which is defined to be a binary expansion with digits {0,±1} with the property that the nonzero digits have alternating signs. We collect known results about this alternating greedy expansion and complement it with other useful properties and algorithms. In the second part, we apply it to give an algorithm for comp...

Steganography consist of concealing secret information in a cover object to be sent over a public communication channel. It allows two parties to share hidden information in a way that no intruder can detect the presence of hidden information. This paper presents a novel steganography approach based on pixel location matching of the same cover image. Here the information is not directly embedde...

We introduce the class MP of languages L which can be solved in polynomial time with the additional information of one bit from a #P function f . We prove that the polynomial hierarchy and the classes ModkP, k ≥ 2, are low for this class. We show that the middle bit of f(x) is as powerful as any other bit, and that a wide range of bits around the middle have the same power. By contrast, the O(l...

The FFT performs butterfly computations on pairs of data elements that differ in a single bit. The computations start from the most significant bit in the index space and proceeds monotonically to the least significant bit. In a binary cube, adjacent nodes differ in a single bit in their addresses. Thus, mapping data to nodes by a binary encoding of the indices is suitable for the FFT. We assum...

In [4], we introduced the alternating greedy expansion of integers, which turned out to be useful in several left-to-right algorihms in cryptography. In this paper, we collect known results about this alternating greedy expansion and complement it with other useful properties and algorithms. In the second part, we apply it to give an algorithm for computing a joint expansion of d integers of mi...