Privacy in Cryptocurrencies: An Overview

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 […]

Comparison of Cryptocurrency Developments

Working for our customers in our blockchain development company we built this spreadsheet which is a work in progress, comments are welcome here, which describes the features of multiple blockchain and sidechain technologies. Views about blockchain technologies range from hype to skepticism. A blockchain is a distributed database and consensus network that can be used to […]

Some Comments on the Security of ECIES with secp256k1

The challenge of modern cryptography is to find efficient but secure encryption schemes. The Elliptic Curve Integrated Encryption Scheme (ECIES) is a widely used encryption scheme which is specified in many standards. It is used for example in Ethereum’s Whisper. While Bitcoin Core does not implement ECIES, it can be employed to send secure messages […]

Interdependent Transactions in Bitcoin, RSK and Ethereum

A recent paper titled The Blockchain Anomaly presents the difficulties the authors encountered when trying to make two transactions interdependent such that the second transaction cannot be executed without the first being confirmed. Although the paper may be useful as a guide, the title is misleading since Bitcoin does not guarantee the order of transactions (no […]

Swagger Specification for Coinbase API v2

Coinbase has official client libraries for Python, Ruby, PHP, Node.js and Java, but what about other languages? Enter Swagger. Swagger is an open-source project which includes an specification for describing APIs in JSON or YAML and tools for generating ready-to-go client libraries in several languages. Here at CoinFabrik, we have been writing a first draft […]

ECDSA Security in Bitcoin and Ethereum: a Research Survey

Elliptic curve cryptography is becoming more and more popular. One of its main supporters is the cryptocurrency system Bitcoin which uses an elliptic curve scheme for their digital signatures. Smaller key size, a more efficient implementation than the RSA system, and a similar level of security make elliptic curve cryptography an interesting alternative to RSA. […]