Peercoin

Peercoin
The Peercoin Logo
Denominations
Subunit
0.001	mPPC (millicoin)
0.000001	μPPC (microcoin)
0.000001	Smallest unit
Plural	PPC, Peercoins
Symbol	Ᵽ
Nickname	Peercoin, PPCoin
Demographics
Date of introduction	12 August 2012, 17:57:38 UTC
User(s)	International
Issuance
Central bank	(Decentralized) None. Peercoin tokens are issued by stakeholders while the currency is regulated by a central authority through checkpointing.
Valuation
Inflation	Limited release rate plus 1% inflation due to the proof-of-stake system.
Method	Proof-of-stake

Peercoin, also known as PPCoin or PPC, is a peer-to-peer cryptocurrency utilizing both proof-of-stake and proof-of-work systems.

Peercoin is based on an August 2012 paper which listed the authors as Scott Nadal and Sunny King. Sunny King, who also created Primecoin, is a pseudonym. Nadal's involvement had diminished by November 2013, leaving King as Peercoin's sole core developer.

Peercoin was inspired by bitcoin, and it shares much of the source code and technical implementation of bitcoin. The Peercoin source code is distributed under the MIT/X11 software license.

Unlike bitcoin, Namecoin, and Litecoin, Peercoin does not have a hard limit on the number of possible coins, but is designed to eventually attain an annual inflation rate of 1%. There is a deflationary aspect to Peercoin as the transaction fee of 0.01 PPC/kb paid to the network is destroyed. This feature, along with increased energy efficiency, aim to allow for greater long-term scalability.

Transactions

A peer-to-peer network handles Peercoin's transactions, balances and issuance through SHA-256, the proof-of-work scheme (Peercoins are issued when a small enough hash value is found, at which point the block of transactions is added to the shared block chain. The process of finding these hashes and creating blocks is called 'mining').

Addresses

Payments in the Peercoin network are made to addresses, which are based on digital signatures. They are strings of 34 numbers and letters which always begin with the letter P. One can create as many addresses as needed without spending any Peercoins. It is quite common to use one address for one purpose only which makes it easy to see who actually sent the Peercoins.

Confirmations

Transactions are recorded in the Peercoin blockchain (a ledger held by most clients), a new block is added to the blockchain with a targeted time of 10 minutes (whenever a small enough hash value is found for the proof-of-work scheme), a transaction is usually considered complete after 6 blocks, or 60 minutes, though for smaller transactions, fewer than 6 blocks may be needed for adequate security.

Creation of new coins

New coins can be created in two different ways; mining and minting. Mining uses the SHA-256 algorithm to directly secure the network. Minting rewards users in proportion to the coins that they hold (targeted at 1% annually). There are long term plans to reduce gradually the amount of mining and to rely more on minting. This is to create a fair distribution and could lead to an increase in the reward from minting.

Distinguishing features

Proof-of-stake

Peercoin's major distinguishing feature is that it uses a hybrid proof-of-stake/proof-of-work system. The proof-of-stake system was designed to address vulnerabilities that could occur in a pure proof-of-work system. With bitcoin, for example, there is a risk of attacks resulting from a monopoly on mining share. This is because rewards from mining are programmed to decline exponentially, which may decrease the incentive to mine. As miners decline, the likelihood of a monopoly increases, which leaves the network vulnerable to a 51% attack (a 51% attack is when a single entity possesses over half the mining share, which would allow this entity to theoretically double-spend a transaction involving their coins). With a proof-of-stake system, new coins are generated based on the holdings of individuals. In other words, someone holding 1% of the currency will generate 1% of all proof-of-stake coin blocks. This has the effect of making a monopoly more costly, and separates the risk of a monopoly from proof-of-work mining shares.

Proof-of-work

The whole network uses the SHA-256 Algorithm. For each 16 times increase in the network, the proof-of-work block reward is halved. In July 2016 the Bitcoin mining reward halved causing a notable minority of miners to switch to mining Peercoin for better profitability. Researcher Adam Hayes explained that the Peercoin network hashrate surged from roughly 500 terahashes per second (TH/s) to 6,500 TH/s following the halving.

Energy efficiency

Peercoin's proof-of-stake system was developed to address the high energy consumption of bitcoin. For example, as of April 2013 the generation of bitcoins was using approximately $150,000 USD per day in power consumption costs. The proof-of-stake method of generating coins requires very minimal energy consumption; it only requires the energy to run the client software on a computer, as opposed to running resource-intensive cryptographic hashing functions. During its early stages of growth, most Peercoins will be generated by proof-of-work like bitcoin, however over time proof-of-work will be phased out as proof-of-work difficulty increases and block rewards decrease. As proof-of-stake becomes the primary source of coin generation, energy consumption (relative to market cap) decreases over time. As of January 2014, roughly 90% of new coins being generated are still from proof-of-work and the energy consumption of Peercoin uses roughly 30% of the energy consumption of bitcoin (scaling for market cap - in terms of value secured per GH/s).

Steady inflation

Peercoin is designed so that it will theoretically experience a steady 1% inflation per year, yielding an unlimited number of coins. This is a combined result of the proof-of-stake minting process, and scaling of mining difficulty with popularity. Although Peercoin technically has a cap of 2 billion coins, it is only for consistency checking, and the cap is unlikely to be reached for the foreseeable future. If the cap were to be reached, it could easily be raised, hence for all practical purposes Peercoin can be considered to have inflation of 1% per year, with a limitless money supply. This was partially designed to address the growing population.

Transaction fees

Peercoin is designed so that variable and optional transaction fees are removed in favor of a protocol defined transaction fee (currently 0.01 PPC/kB). The transaction fee is fixed at the protocol level and does not go to miners but is destroyed instead. This is intended to offset inflation by deflating the money supply and serves to self-regulate transaction volume, and stop network spam. One issue with a protocol defined transaction fee is that it does not evolve with the value of currency units, and requires a hardfork of the protocol to adjust transaction fees.

PeerAssets

PeerAssets is a simple, blockchain agnostic protocol which enables peers to issue and transact with assets. PeerAsset protocol based assets can be utilized to represent any type of asset like bonds or equity. This allows the creation of DAOs and DACs on the Peercoin blockchain, complete with dividend functionality as well as shareholder voting.

Indicium

Indicium is a financially driven token-issuance DAC built using PeerAssets, hosted on the Peercoin blockchain. It will form algorithmically chosen indices and baskets of cryptocurrencies and issue assets corresponding to the value of these baskets. Peercoin dividends and voting rights will be given to Indicium (IND) holders as a representation of ownership in the DAC. A federated approach will be taken, where a group of founders or a board of directors will perform managerial duties to facilitate operation.

Indicium completed a Series A financing on May 24, 2017, reaching the maximum Series A funding limit of $250,000.00.

Other

Checkpointing

According to the original paper, Peercoin uses a centrally broadcast checkpoint mechanism. The paper cites Ben Laurie's argument that “Bitcoin has not completely solved the distributed consensus problem as the mechanism for checkpointing is not distributed.” King notes that he attempted to design a distributed alternative, but ultimately concluded that a centralized solution was acceptable until a distributed solution became available. Released on November 1, 2017, v0.6.0 of the protocol allows users to opt-out of checkpointing.

See also

• Alternative currency
• Neucoin
• Peer-to-peer computing

External links

Media related to PPCoin at Wikimedia Commons

• Official website
• Official Peercoin white paper