Hartwig Mayer, Autor de CoinFabrik Blog

Censorship of Harmful Data in Blockchains

October 10, 2019October 10, 2019 Hartwig MayerNo Comments

Reading Time: 17 minutes

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?

What are the Benefits of Threshold Signatures for Crypto Wallets?

October 1, 2019October 1, 2019 Hartwig MayerNo Comments

Reading Time: 6 minutes

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.

Immutability: Is There a Limit?

September 30, 2019October 17, 2019 Hartwig MayerNo Comments

Reading Time: 14 minutes

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?

Publishing Text and Images in Bitcoin

June 13, 2019June 20, 2019 Hartwig MayerNo Comments

Reading Time: 4 minutes

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.

A Short Guide Through the Universe of Blockchain Based Micropayment Systems

May 6, 2019May 6, 2019 Hartwig MayerNo Comments

Reading Time: 7 minutes

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 […]

Some Insights into Cardano ´s Blockchain

December 11, 2018April 17, 2019 Hartwig MayerNo Comments

Reading Time: 5 minutes

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.

Comparison of PoS projects: Unbiased Leader Election

July 18, 2018April 17, 2019 Hartwig MayerNo Comments

Reading Time: 7 minutes

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

Survey of Blockchain Storage and Computing Services

January 11, 2018June 21, 2018 Hartwig Mayer1 Comment

Reading Time: 10 minutes

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 […]

Survey of Decentralized Exchanges

November 23, 2017June 21, 2018 Hartwig MayerNo Comments

Reading Time: 6 minutes

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 […]

Emerging New Trends in Blockchain Technologies

September 28, 2017April 17, 2019 Hartwig Mayer3 Comments

Reading Time: 2 minutes

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 […]

Value at Risk & Expected Shortfall of Cryptocurrencies

September 7, 2017April 17, 2019 Hartwig MayerNo Comments

Reading Time: 4 minutes

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 […]

Privacy in Cryptocurrencies: An Overview

May 16, 2017April 17, 2019 Hartwig Mayer2 Comments

Reading Time: 2 minutes

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 […]