Cryptographic nonce

noncenoncesauthentication nonce
Similarly, the bitcoin blockchain hashing algorithm can be tuned to an arbitrary difficulty by changing the required minimum/maximum value of the hash so that the number of bitcoins awarded for new blocks does not increase linearly with increased network computation power as new users join. This is likewise achieved by forcing bitcoin miners to add nonce values to the value being hashed to change the hash algorithm output.

Private currency

private currencieslimited means of paymentprivate
In terms of total market value, Bitcoin is the largest cryptocurrency, but there are over 700 digital currencies in existence. On 6 August 2013, Federal Judge Amos Mazzant of the Eastern District of Texas of the Fifth Circuit ruled that bitcoins are "a currency or a form of money" (specifically securities as defined by Federal Securities Laws), and as such were subject to the court's jurisdiction. In August 2013, the German Finance Ministry characterized Bitcoin as a unit of account, usable in multilateral clearing circles and subject to capital gains tax if held less than one year. In Thailand, lack of existing law leads many to believe Bitcoin is banned.

Ledger (journal)

LedgerLedger'' (journal)
Ledger is the first peer-reviewed academic journal dedicated to cryptocurrency and blockchain technology research. The journal covers aspects of mathematics, computer science, engineering, law, economics and philosophy that relates to cryptocurrencies such as bitcoin. Ledger is an open access journal published by the University Library System (ULS) of the University of Pittsburgh and is cosponsored by the University of Pittsburgh Press. The journal expects to release full-publications twice a year and additional articles throughout.


spear phishingspear-phishinganti-phishing
Some companies, for example PayPal, always address their customers by their username in emails, so if an email addresses the recipient in a generic fashion ("Dear PayPal customer") it is likely to be an attempt at phishing. Furthermore, PayPal offers various methods to determine spoof emails and advises users to forward suspicious emails to their domain to investigate and warn other customers.

List of online payment service providers

The following is a list of notable online payment service providers and payment gateway providing companies, their platform base and the countries they offer services in:

List of bitcoin forks

Hard forks splitting bitcoin (aka "split coins") are created via changes of the blockchain rules and sharing a transaction history with bitcoin up to a certain time and date. The first hard fork splitting bitcoin happened on 1 August 2017, resulting in the creation of Bitcoin Cash. The following is a list of hard forks splitting bitcoin by date and/or block: * The fork fixing the value overflow incident was controversial because it was announced after the exploit was mined. Two hard forks were created by "protocol change" definition: Bitcoin XT. Bitcoin Classic. Bitcoin Unlimited. Bitcoin Cash: Forked at block 478558, 2017-08-01, for each bitcoin (BTC), an owner got 1 Bitcoin Cash (BCH).


ledgersledger bookaccount book
A ledger is the principal book or computer file for recording and totaling economic transactions measured in terms of a monetary unit of account by account type, with debits and credits in separate columns and a beginning monetary balance and ending monetary balance for each account.

Node (networking)

nodenodesnetwork node
In telecommunications networks, a node (Latin nodus, ‘knot’) is either a redistribution point or a communication endpoint. The definition of a node depends on the network and protocol layer referred to. A physical network node is an active electronic device that is attached to a network, and is capable of creating, receiving, or transmitting information over a communications channel. A passive distribution point such as a distribution frame or patch panel is consequently not a node.

Central bank

central bankscentral bankingcentral banking system
A central bank, reserve bank, or monetary authority is an institution that manages a state's currency, money supply, and interest rates. Central banks also oversee the commercial banking system of their respective countries. In contrast to a commercial bank, a central bank possesses a monopoly on increasing the monetary base in the state, and also prints the national currency, which serves as the state's legal tender. Central banks also act as a "lender of last resort" to the banking sector during times of financial crisis.

Cryptographic hash function

cryptographic hashhashhashing
One popular system – used in Bitcoin mining and Hashcash – uses partial hash inversions to prove that work was done, to unlock a mining reward in Bitcoin and as a good-will token to send an e-mail in Hashcash. The sender is required to find a message whose hash value begins with a number of zero bits. The average work that sender needs to perform in order to find a valid message is exponential in the number of zero bits required in the hash value, while the recipient can verify the validity of the message by executing a single hash function. For instance, in Hashcash, a sender is asked to generate a header whose 160 bit SHA-1 hash value has the first 20 bits as zeros.

Fractional-reserve banking

fractional reserve bankingfractional reserve systemfractional reserves
Politician Ron Paul has also criticized fractional reserve banking based on Austrian School arguments. 1) Central bank money: money created or adopted by the central bank regardless of its form – precious metals, commodity certificates, banknotes, coins, electronic money loaned to commercial banks, or anything else the central bank chooses as its form of money. 2) Commercial bank money: demand deposits in the commercial banking system; also referred to as "chequebook money", "sight deposits" or simply "credit". 1) Minimum required reserve ratios (RRRs). 2) Minimum capital ratios. 3) Government bond deposit requirements for note issue. 4) 100% Marginal Reserve requirements for note issue, such

European Central Bank

ECBThe European Central Bankmonetary policy
The European Central Bank (ECB) is the central bank for the euro and administers monetary policy of the Eurozone, which consists of 19 EU member states and is one of the largest currency areas in the world. It is one of the world's most important central banks and is one of the seven institutions of the European Union (EU) listed in the Treaty on European Union (TEU). The capital stock of the bank is owned by the central banks of all 28 EU member states. The Treaty of Amsterdam established the bank in 1998, and it is headquartered in Frankfurt, Germany.

Broadcasting (networking)

In computer networking, telecommunication and information theory, broadcasting is a method of transferring a message to all recipients simultaneously. Broadcasting can be performed as a high level operation in a program, for example broadcasting in Message Passing Interface, or it may be a low level networking operation, for example broadcasting on Ethernet.

Money transmitter

money transfer servicemoney transfer servicesmoney transfer financial services
FINCEN has also ruled that Informal Value Transfer Systems (IVTS) are considered money transmitters for the purposes of registration and licensing. FINCEN defines an IVTS as "any system, mechanism, or network of people that receives money for the purpose of making the funds or an equivalent value payable to a third party in another geographic location, whether or not in the same form". These are known as Hawala in the Middle East, Afghanistan and Pakistan, as "hundi" in India and '"fei ch’ien" in China.

People's Bank of China

central bankPeople’s Bank of ChinaCentral Bank Governor
The People's Bank of China (PBC or PBOC; ) is the central bank of the People's Republic of China responsible for carrying out monetary policy and regulation of financial institutions in mainland China, as determined by Bank Law. Valued at US$3.21 trillion, The People's Bank of China has had the largest financial asset holdings of any central bank in the world since July 2017. Though possessing a high degree of independence by Chinese standards, it remains a department of the State Council.


bankerbankingbanking system
A bank is a financial institution that accepts deposits from the public and creates credit. Lending activities can be performed either directly or indirectly through capital markets. Due to their importance in the financial stability of a country, banks are highly regulated in most countries. Most nations have institutionalized a system known as fractional reserve banking under which banks hold liquid assets equal to only a portion of their current liabilities. In addition to other regulations intended to ensure liquidity, banks are generally subject to minimum capital requirements based on an international set of capital standards, known as the Basel Accords.


onlinethe Internetweb
The Internet (contraction of interconnected network) is the global system of interconnected computer networks that use the Internet protocol suite (TCP/IP) to link devices worldwide. It is a network of networks that consists of private, public, academic, business, and government networks of local to global scope, linked by a broad array of electronic, wireless, and optical networking technologies. The Internet carries a vast range of information resources and services, such as the inter-linked hypertext documents and applications of the World Wide Web (WWW), electronic mail, telephony, and file sharing.

Electronic Fund Transfer Act

Electronic Funds TransferEFTAElectronic Funds Transfer Act
The Electronic Fund Transfer Act was passed by the U.S. Congress in 1978 and signed by President Jimmy Carter, to establish the rights and liabilities of consumers as well as the responsibilities of all participants in electronic funds transfer activities.

Venture capital

venture capitalistventure capitalistsventure capital firm
Venture capital (VC) is a type of private equity, a form of financing that is provided by firms or funds to small, early-stage, emerging firms that are deemed to have high growth potential, or which have demonstrated high growth (in terms of number of employees, annual revenue, or both). Venture capital firms or funds invest in these early-stage companies in exchange for equity, or an ownership stake, in the companies they invest in. Venture capitalists take on the risk of financing risky start-ups in the hopes that some of the firms they support will become successful. Because startups face high uncertainty, VC investments do have high rates of failure.


chargebackscharge back
Payment service providers, such as PayPal, have a similar policy. PayPal Merchant charges $20 for each chargeback (regardless of whether or not it is the first) plus it will retain the original transaction fee. In addition, Visa and MasterCard may levy severe fines against acquiring banks that retain merchants with high chargeback frequency. Acquirers typically pass such fines directly to the merchant. Merchants whose ratios stray too far out of compliance may trigger card association fines of $100 or more per chargeback. Accounts may also incur credit reversals in other forms. ATM reversals occur when an ATM deposit envelope is found to have fewer funds than represented by the depositor.