Auroracoin is a decentralised, peer-to-peer, and secure cryptocurrency released as an alternative to the Icelandic Króna to bypass governmental restrictions associated with the national fiat currency. It was launched with the aim of becoming the ‘official’ cryptocurrency of Iceland. AUR was a pioneer in the area of country-specific cryptocurrencies. AUR was launched on the 25th of January, 2014, by an anonymous developer who went by the pseudonym of Baldur Friggjar Óðinsson. It was originally based on Litecoin, using the Scrypt algorithm with a Proof of Work mechanism, but was later updated to use a multi-algorithm architecture in 2016, forked from DigiByte. Auroracoin uses the PoW consensus mechanism, which utilises device hashing power to solve a complex mathematical problem in order to authenticate a transaction proposed to be stored in the blockchain. The difficulty of solving the problem ensures that authenticating forged transactions is very difficult unless the attacker owns an impractically large chunk of the network’s total hashing power. AUR is one of the only cryptocurrencies to use a combination of five different hashing algorithms, namely Grøstl, Qubit, scrypt, SHA-256, and Skein. While initially very popular, Auroracoin has seen little to no activity for a while, with poor marketing, and frequent dev team changes. Reasons for little growth have been various, from slow adoption in Iceland, to developers leaving and joining the project midway. However, it is expected to not go lower than the recent low, and might see a rise as AUR plans to launch a more aggressive marketing campaign in Iceland to promote the coin among the masses. Unlike most other altcoins, Auroracoin has made extensive changes to the original codebase. It has introduced security measures such as Automatic checkpointing, and protecting against known flaws present in the BTC blockchain, such as 51% block replacement attacks.
Zen is a decentralized financial platform, built from scratch with the goal of providing people with a secure, scalable and useful infrastructure for creating their own financial instruments, and trading them directly without intermediaries.The Zen blockchain is secured by multiple proof-of-work algorithms, with token-holder voting on the balance between them. Multi-hash mining creates robust incentives for miners to deliver efficient, reliable security.Zen smart contracts are written and secured by a subset of the F* functional programming language, allowing users to: A) Prove the amount of resources a contract will consume and provide the necessary fees for running the contract to miners, removing the need for a “gas” based system.B) Prove their contracts meet a given specification, meaning they can prove the contract will definitely do (or not do) something given a specific set of parameters.The Zen platform comes with a built-in solution for oracles, which provide contracts with useful real world data.Finally, Zen is integrated with the Bitcoin blockchain, allowing contracts to observe and respond to native bitcoin transactions