BitCoin transactions are malleable in a sense that given a transaction an adversary can easily construct an equivalent transaction which has a different hash. This can pose a serious problem in some BitCoin distributed contracts in which changing a transaction’s hash may result in the protocol disruption and a financial loss. The problem mostly concerns protocols, which use a ”refund” transacti...

Although Bitcoin is often perceived to be an anonymous currency, research has shown that a user’s Bitcoin transactions can be linked to compromise the user’s anonymity. We present solutions to the anonymity problem for both transactions on Bitcoin’s blockchain and off the blockchain (in so called micropayment channel networks). We use an untrusted third party to issue anonymous vouchers which u...

There has been an enormous increase of transactions and cooperative-computing services on the Internet. This is both a technical and a social phenomenon. Transactions and services over the Internet have global reach and users, known or unknown to the service provider, might be interested in availing the access or participate in the cooperative transaction in a distributed manner. Thus, it is ve...

This paper provides an argument against understanding risk-taking in design education as something ideally need of only being calculable and formalisable. Using the German sociologist Ulrich Beck’s theory on risktaking combined with current discourse thinking, together analysis a three week-long interdisciplinary workshop, we analyse discuss how - general concept is inherent element itself. We ...

We show that as soon h ? ? $h\rightarrow \infty$ with X $X \rightarrow , almost all intervals ( x ? log ] $(x-h\log X, x]$ ? / 2 $x \in (X/2, X]$ contain a product of at most two primes. In the proof we use Richert's weighted sieve, arithmetic information eventually coming from results Deshouillers and Iwaniec on averages Kloosterman sums.