Peercoin (PPC) Logo
中央銀行 なし PeercoinのP2Pネットワークプロトコルの同意によって与えられる※1
開始日 2012年8月12日、午前17時57分38秒(世界標準時)
ユーザー 世界中
備考 proof-of-stake systemによって上限1%のインフレを起こす
0.001 mPPC (millicoin)
0.000001 μPPC (microcoin)
0.00000001 最小単位
表記 Ᵽ, PPC
呼び方 Peercoin, PPCoin, P2PCoin, PPC

Peercoin Peercoinの概要

Peercoin (code: PPC), also known as PPCoin and Peer-to-Peer Coin is the first cryptocurrency based on an implementation of a combined proof-of-stake (PoS)/proof-of-work system (PoW).
Peercoin was created by software developer Sunny King (who later developed the cryptocurrency Primecoin) in August 2012. 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.
As of 28 December 2013, Peercoin is the 5th largest cryptocurrency according to market capitalization estimates.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 percent. This feature, along with increased energy efficiency, aim to allow for greater long-term scalability.
Peercoin(コード:PPC)はPPCoinやPPCoin and Peer-to-Peer Coinという名前でproof-of-stake (PoS※1)とproof-of-work system (PoW※2)を組み合わせた仮想通貨として知られています。
Peercoinはソフトウェアデベロッパ(開発者)のSunny Kingによって作成されました。(彼は後に仮想通貨のプライムコインを開発しました。)PeercoinはBitcoinの影響を受け、そして多くのBitcoinのソースコードや技術的実装を取り入れました。
PeercoinのソースコードはMIT/X11ソフトウェアライセンスのもとに配布されています。 MIT/X11ライセンスとはマサチューセッツ工科大学が起源のライセンス条項のことです。詳しくは、wikiへ
※1proof-of-stake とは所持金の証明
※2proof-of-work とは自分が見つけたブロックの証明(マイニングで見つけたもの)

Transactions 取引

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).
Peercoins are currently traded for fiat currencies, bitcoins, and other cryptocurrencies, mostly on online exchanges. Reversible transactions (such as those with credit cards) are not normally used to buy Peercoins as Peercoin transactions are
irreversible, so there is the danger of chargebacks.

Addresses アドレス

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 承認

Transactions are recorded in the Peercoin blockchain (a ledger held by most clients), a new block is added to the blockchain roughly every 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, less than 6 blocks may be needed for adequate security.

Distinguishing features 特徴の分類


Peercoin's major distinguishing feature is that it uses proof-of-stake/proof-of-work hybrid 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 double-spend 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.
The proof-of-stake system also has other effects (listed below).
Peercoinで有名なことは認証を proof-of-stakeとproof-of-workとの混合で行うシステムです。 proof-of-stakeは元々の proof-of-stakeで発生する可能性がある脆弱性に対処するために設計されました。例えばBitcoinの場合、マイニングのシェアの独占による
51%アタックをすることを許してしまうことになる。(51%アタックとは一箇所に半分以上のマイニングシェアが集まり、そしてその一箇所にコインの二重の支出を許してしまうことです。※) proof-of-stakeでは、新しいコインは個々の財産を元に産み出されます。
The proof-of-stakeは他にも色々な機能(効果)があります。(以下に示します。)


SHA-256. For each 16x increase in the network, the proof-of-work block reward is halved.
SHA-256(※) 16の倍数に達すると、 proof-of-workの報酬は半減します。

Energy efficiency インフレの原動力

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, 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 rewards decrease.Proof-of-stake will then become the primary source of coin generation, which will lead to a >decrease in energy consumption over time.
Bitcoinnoのようにproof-of-workによって生成しますが、時間がたつごとに proof-of-workはDifficultyが上昇し、報酬は減っていきます。そうなったとき、Proof-of-stakeはコインを生成する主要な方法となっていきそれはエネルギー消費を抑えることになります。

Steady inflation 継続的なインフレーション

Peercoin is designed so that it will theoretically experience a steady 1% "decentralized" 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.

Deflationary aspect デフレ的な側面

The Peercoin transaction fee is fixed at 0.01 PPC for every transaction; however, the fee does not go to miner's income, but rather destroyed in order to offset the inflation caused by the proof-of-stake minting process. Therefore, if the network's economic >activity and transaction volume grows, it follows that the deflationary aspect will also rise proportionally according to the "network effect". For every 1 unit of PPC created there can be about 100 transactions before it is completely deflated away, this is >designed to ensure that there is no overall change in the money supply. The developers hope that if inflation increases, then transaction costs become cheaper which increases the urge to participate in transactions; however, if deflation increases, then >transaction costs become more expensive which increases the urge to save more, which in turn produces more "decentralized" inflation.
Peercoinのすべての取引手数料は、0.01 PPCに固定されています。しかしながら、この料金はマイナーの手元に届かず、これはproof-of-stakeコイン生成システムのインフレを相殺するために消えてゆきます。したがって、もしネットワークの経済規模と

Transaction fees 取引の料金

Peercoin designed so that variable and optional transaction fees are removed in favor of a protocol defined transaction fee (currently 0.01 PPC). 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.
Peercoinの変更することができる取引手数料(現在は0.01 PPC)は、多数決によってプロトコルによって削除されるように設計されている。取引手数料はプロトコルレベルで固定され、マイナーのものにならないが、代わりに破棄されます。これは、

Money supply 通貨の総量

There are 20.7 million Peercoins in existence as of November 19, 2013 and the current inflation created by proof-of-work mining is at about 8%.
The change of Peercoin money supply is determined by:

  • Proof-of-work mining (increases supply)
  • Proof-of-work difficulty (higher difficulty decreases reward per block)
  • Number of transactions (more transactions decrease supply because of the current 0.01 PPC transaction fee)
  • Proof-of-stake system (increases supply at a rate of up to 1% per year)
  • Proof-of-work mining (供給 (マイニング) による増加)
  • Proof-of-work difficulty (高いdifficultyによる供給の減少)
  • 取引件数(多量の 年間のインフレーション率を越える 0.01PPCの取引手数料によって減少)
  • Proof-of-stake system (年間1%のインフレーションによる増加)

Hence: その結果、

  • The more people are mining, the smaller the block reward gets. This is intended to decrease energy consumption in the long term.
  • The more people are using Peercoin as a currency and exchange them, the more Peercoins will be burned as transaction fees.
  • The more people are saving Peercoin, the nearer the PoS inflation will be to 1% per year, (approximately compounding every 520 blocks, or about once per month).
  • ブロックの報酬が少なくなるごとにマイニングする人も少なくなっていく。これは、長期的にエネルギー消費を減少させることを意図している。
  • 多くの人がPeercoinを使うとき、多くのPeercoinが取引手数料としてなくなってゆく。
  • 多くの人がPeercoinを貯めこんでいれば、 PoSによる年間インフレーション率の1%に近づく。およそ520ブロック約1ヶ月に1回供給する。

If Peercoin grows rapidly, stake minting may temporarily decrease as coin days are lost when trading, this would cause Peercoin to become deflationary. The flat nature of the transaction fees is intended to counter this by decreasing total transaction >volume. Proponents of Peercoin argue that this will decrease deflation.
Peercoinが急速に成長した場合にコインが減ったままになって、PoSによる生成が一時的に低下することがあり、これによってPeercoinがデフレになる可能性があります。。取引手数料が一定であるという仕様は、総取引量を減少させることによってこれに対処することを意図しています。 Peercoinの支持者はこれはデフレを減少させると主張している。

The actual money supply curve is totally dependent on market interest, user adoption, and the Peercoin price. At the current adoption rate, the network is now producing less than 150k Peercoins by proof-of-work per month, and less per month as each month >goes by; thus, the math proves it will likely take over 1,000 years to reach 2.1 billion coins, if ever.

Issues/controversies 問題/論争

Centralized check pointing 1元化されたチェックポイント(中央的な検証地点)について

Peercoin is not truly a completely decentralized currency as it still requires centralized check pointing to avoid several issues. The developer has announced however that this check pointing is only a temporary measure which will be removed once the >currency grows sufficiently stable. "As of our v0.2 centrally broadcast checkpointing is no longer a critical part of the protocol. Its main purpose now is to defend the network during the initial growth period and help ensure a smooth upgrade path if >critical vulnerability is found. We are confident that central checkpointing can now be gradually weakened and eventually removed to achieve similar decentralization level of Bitcoin as the Peercoin network matures." It is also important to distinguish that >even though the checkpoints are centralized, this does not mean the whole network is centralized. Every major and essential aspect of the network such as coin ownership, mining, and minting is fully decentralized and distributed Peer-to-Peer and cannot be >manipulated or controlled.

It is planned to further decentralize Peercoin by gradually removing the checkpoint beginning with software version v.0.5. The current version is v.0.3 (19/11/2013).

The checkpoint system in Peercoin also builds in a consistency check to protect network if the checkpoint key is compromised. This means that the network cannot be arbitrarily shutdown either. The defence mechanism is claimed to be much more effective >against a sustained 51% attack and a great asset to help smaller networks.