Public blockchains allow insertion of arbitrary data. Even specific-purpose blockchains like Bitcoin already contain a lot of non-financial data. Although this data insertion can be beneficial in some use cases (e.g. proof of existence), it can also cause damage. If a blockchain contained videos with instructions on how to torture someone, there would immediately be broad consensus that this data must be deleted. But since blockchains are supposed to be immutable databases, the question is: what can be done if this happens?
The security of your crypto-assets depends on one piece of information that you must protect: your private key. If your private key is stolen, all your assets can be stolen. If your private key is lost, all your assets are lost.
Any information stored in a blockchain is supposed to be preserved forever, nobody will be able to change it or even less erase it. But is this really true? Is there any chance that governments or private groups with enough money to finance costly attacks might delete information from a blockchain?
Blockchains are already used to store non-financial data for diverse purposes, e.g. to prove authorship of ideas or to prove the existence of a document. One of the largest files stored successfully into the Bitcoin blockchain is an image of Nelson Mandela.
Micropayment take place in pay-as-you-go software service models, micro donations, and the Internet of Things (IoT). In these contexts payments for values which are usually under the smallest unit of fiat money (e.g. $0.001) are needed. Prepaid cards can solve this problem. Another approach uses cryptocurrencies in the blockchain, having the advantage of allowing exact […]
In this blog post, we present a high-level overview of the paper describing the Ouroboros Proof of Stake protocol implemented in Cardano´s blockchain. After the overview follow some comments about theoretical aspects of the protocol.
In general, Proof of Stake (PoS) consensus protocols elect the network nodes responsible to send the next block to the blockchain on the basis of the nodes’ amount of stake.
Prior to the Bitcoin blockchain of “Satoshi Nakamoto”, distributed ledger systems were lacking two important properties which are essential for a decentralized digital cash system. The first property which existing distributed ledger systems were missing, was the ability to scale to a network of millions of users. And secondly, systems at the time were not permissionless
Introduction Public blockchains are not suited to function as a data storage provider. Since they are append-only ledgers, storing many large files would result in a dramatic increase of the whole distributed ledger. That would force the network nodes to store huge databases leaving it in the hands of just a few providers. Likewise, the […]
Cryptocurrency Exchanges Anyone who wants to get into the cryptocurrency market and does not want to mine blocks needs to exchange his fiat money at an exchange, the only alternative to this is to get cryptocurrency from another holder. Centralized exchanges like Bitfinex, Coinbase, Kraken, Poloniex or Shapeshift intermediate the bid and offer matching process […]
We are compiling a list of recent technologies developments in the blockchain sector. Our focus is mostly on projects which promise scalability, but includes also proposals which aim to overcome some deficiencies in Bitcoin´s PoW based blockchain, e.g. which aim to improve fairness, usefulness, or privacy. You can find the current state of our work […]
It is important to have an estimate of risk for a portfolio when trading with financial assets. Two basic and commonly used risk measures are value-at-risk and expected shortfall. We will illustrate the two concepts with an example and provide the necessary R code to actually calculate the values of both measures. If we take […]
Transactions in Bitcoin are recorded in its blockchain. This makes it possible to see whether coins sent through the network are still valid unspent coins. At the same time, however, the transparency of the data stored in the blockchain can be used to infer private information of users. There are already many cryptocurrencies and “money […]