The bitcoin network is a peer-to-peer payment network that operates on a cryptographic protocol. Users send and receive bitcoins, the units of currency, by broadcasting digitally signed messages to the network using bitcoin cryptocurrency wallet software. Transactions are recorded into a distributed, replicated public database known as the blockchain, with consensus achieved by a proof-of-work system called mining. Satoshi Nakamoto, the designer of bitcoin claimed that design and coding of bitcoin began in 2007. The project was released in 2009 as open source software. The network requires the minimal structure to share transactions. An ad hoc decentralized network of volunteers is sufficient. Messages are broadcast on a best effort basis, and nodes can leave and rejoin the network at will. Upon reconnection, a node downloads and verifies new blocks from other nodes to complete its local copy of the blockchain. A bitcoin is defined by a sequence of digitally signed transactions that began with the bitcoin's creation, as a block reward. The owner of a bitcoin transfers it by digitally signing it over to the next owner using a bitcoin transaction, much like endorsing a traditional bank check. A payee can examine each previous transaction to verify the chain of ownership. Unlike traditional check endorsements, bitcoin transactions are irreversible, which eliminates the risk of chargeback fraud. Although it is possible to handle bitcoins individually, it would be unwieldy to require a separate transaction for every bitcoin in a transaction. Transactions are therefore allowed to contain multiple inputs and outputs, allowing bitcoins to be split and combined. Common transactions will have either a single input from a larger previous transaction or multiple inputs combining smaller amounts, and one or two outputs: one for the payment, and one returning the change, if any, to the sender. Any difference between the total input and output amounts of a transaction goes to miners as a transaction fee. In 2013, Mark Gimein estimated electricity consumption to be about 40.9 megawatts (982 megawatt-hours a day). In 2014, Hass McCook estimated 80.7 megawatts (80,666 kW). As of 2015, The Economist estimated that even if all miners used modern facilities, the combined electricity consumption would be 166.7 megawatts (1.46 terawatt-hours per year). To lower the costs, bitcoin miners have set up in places like Iceland where geothermal energy is cheap and cooling Arctic air is free. Chinese bitcoin miners are known to use hydroelectric power in Tibet to reduce electricity costs. Various potential attacks on the bitcoin network and its use as a payment system, real or theoretical, have been considered. The bitcoin protocol includes several features that protect it against some of those attacks, such as unauthorized spending, double spending, forging bitcoins, and tampering with the blockchain. Other attacks, such as theft of private keys, require due care by users.
Enigma is a crypto platform that’s trying to solve the problem of privacy on the blockchain by giving them access to much-needed storage, privacy, and scalability. Enigma wants to extend Ethereum Smart Contracts by introducing secret contracts, a brand of smart contract that gives users an element of privacy that’s not intrinsic to current blockchain protocols. These contracts operate off-chain, meaning the execution of the Smart Contract doesn’t occur on the Ethereum blockchain itself. This is how the Enigma protocol works: it breaks up the Smart Contract and any related data into pieces, encrypts those pieces, and distributes them redundantly among Enigma nodes. Enigma has a protocol level. The Enigma privacy protocol allows for decentralized computation of sensitive data. It has a platform layer too. On this protocol, dozens of platforms such as data marketplaces and AI exchanges can be built. In its application layer, it enables thousands of truly decentralized apps that require private computation and secure data.Its first application is catalyst. Catalyst is the first application to be built on the Enigma protocol, already active with tens of thousands of users. Catalyst is a revolutionary platform for data-driven cryptoasset investing and research, built for professional crypto traders. Enigma has a team of MIT graduates, and they’ve been working diligently to ensure Enigma’s success. Guy Zyskind, Enigma’s CEO and cofounder, helped start the project while he was still a student at MIT. He has more than a decade of software development experience with an M.S. from MIT. Sandy Pentland, a well known MIT data scientist who gained fame for his work in data-mining social interactions, is Zyskind and Nathan’s adviser on Enigma. With other advisors such as Alex Pentland, who sits on the Advisory Boards for Google and Nissan, CEO of Abra, Bill Barhydt and director of MIT media lab, Prof. Alex Pentland, it is hard to difficult a fault in the team.