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@ -229,7 +229,7 @@ Gridcoin was introduced in October 2013. It supplements scrypt-based Proof-Of-Wo
==== Anonymity-Focused Alt-Coins: CryptoNote, Bytecoin, Monero, Zerocash/Zerocoin, Darkcoin ==== Anonymity-Focused Alt-Coins: CryptoNote, Bytecoin, Monero, Zerocash/Zerocoin, Darkcoin
Bitcoin is often mistakenly characterized as "anonymous" currency. In fact, it is relatively easy to connect identities to bitcoin addresses and, using big-data analytics, connect addresses to each other to form a comprehensive picture of someone's bitcoin spending habits. Several alt-coins aim to address this issue directly by focusing on strong anonymity. The first such attempt is most likely _Zerocoin_, a meta-coin protocol for preserving anonymity on top of bitcoin, introduced with a paper in the 2013 IEEE Symposium on Security and Privacy. Zerocoin will be implemented as a completely separate alt-coin called Zerocash, currently in development. An alternative approach to anonymity was launched with _CryptoNote_ in a paper published in October 2013. CryptoNote is a foundational technology that is implemented by a number of alt-coin forks discussed next. In addition to Zerocash and Cryptonotes, there are several other independent anonymous coins, such as Darkcoin that use stealth addresses or transaction re-mixing to deliver anonymity. Bitcoin is often mistakenly characterized as "anonymous" currency. In fact, it is relatively easy to connect identities to bitcoin addresses and, using big-data analytics, connect addresses to each other to form a comprehensive picture of someone's bitcoin spending habits. Several alt-coins aim to address this issue directly by focusing on strong anonymity. The first such attempt is most likely _Zerocoin_, a meta-coin protocol for preserving anonymity on top of bitcoin, introduced with a paper in the 2013 IEEE Symposium on Security and Privacy. Zerocoin will be implemented as a completely separate alt-coin called Zerocash, currently in development. An alternative approach to anonymity was launched with _CryptoNote_ in a paper published in October 2013. CryptoNote is a foundational technology that is implemented by a number of alt-coin forks discussed next. In addition to Zerocash and CryptoNotes, there are several other independent anonymous coins, such as Darkcoin that use stealth addresses or transaction re-mixing to deliver anonymity.
*Zerocoin/Zerocash* *Zerocoin/Zerocash*
@ -237,61 +237,61 @@ Zerocoin is a theoretical approach to digital currency anonymity introduced in 2
*CryptoNote* *CryptoNote*
CryptoNote is a reference implementation alt-coin that provides the basis for anonymous digital cash that was introduced in October 2013. It is designed to be "forked" into different implementations and has a built-in periodic reset mechanism that makes it unusable as a currency itself. Several alt-coins have been spawned from CryptoNote, including Bytecoin (BCN), Aeon (AEON), Boolberry (BBR), duckNote (DUCK), Fantomcoin (FCN), Monero (XMR), MonetaVerde (MCN) and Quazarcoin (QCN). CryptoNote is also notable for being a complete ground-up implementation of a crypto-currency, not a fork of bitcoin. CryptoNote is a reference implementation alt-coin that provides the basis for anonymous digital cash that was introduced in October 2013. It is designed to be "forked" into different implementations and has a built-in periodic reset mechanism that makes it unusable as a currency itself. Several alt-coins have been spawned from CryptoNote, including Bytecoin (BCN), Aeon (AEON), Boolberry (BBR), duckNote (DUCK), Fantomcoin (FCN), Monero (XMR), MonetaVerde (MCN), and Quazarcoin (QCN). CryptoNote is also notable for being a complete ground-up implementation of a crypto-currency, not a fork of bitcoin.
*Bytecoin* *Bytecoin*
Bytecoin was the first implementation spawned from CryptoNote, offering a viable anonymous currency based on the CryptoNote technology. Bytecoin was launched in July of 2012. Note that there was a previous alt-coin named Bytecoin with currency symbol BTE, whereas the CryptoNote-derived Bytecoin has currency symbol BCN. Bytecoin uses the Cryptonight Proof-of-Work algorithm which requires access to at least 2 MB of RAM per instance, making it unsuitable for GPU or ASIC mining. Bytecoin inherits ring-signatures, unlinkable transactions and blockchain-analysis resistant anonymity from CryptoNote. Bytecoin was the first implementation spawned from CryptoNote, offering a viable anonymous currency based on the CryptoNote technology. Bytecoin was launched in July of 2012. Note that there was a previous alt-coin named Bytecoin with currency symbol BTE, whereas the CryptoNote-derived Bytecoin has currency symbol BCN. Bytecoin uses the Cryptonight Proof-Of-Work algorithm, which requires access to at least 2 MB of RAM per instance, making it unsuitable for GPU or ASIC mining. Bytecoin inherits ring-signatures, unlinkable transactions, and blockchain-analysis resistant anonymity from CryptoNote.
* Block generation: 2 minutes * Block generation: 2 minutes
* Total currency: 184 billion BCN * Total currency: 184 billion BCN
* Consensus algorithm: Cryptonight Proof-of-Work * Consensus algorithm: Cryptonight Proof-Of-Work
* Market capitalization: $3 million USD in mid-2014 * Market capitalization: $3 million USD in mid-2014
*Monero* *Monero*
Monero is another implementation of CryptoNote. It has a slightly flatter issuance curve than Bytecoin, issuing 80% of the currency in the first 4 years. It offers the same anonymity features inherited from CryptoNote. Monero is another implementation of CryptoNote. It has a slightly flatter issuance curve than Bytecoin, issuing 80% of the currency in the first four years. It offers the same anonymity features inherited from CryptoNote.
* Block generation: 1 minute * Block generation: 1 minute
* Total currency: 18.4 million XMR * Total currency: 18.4 million XMR
* Consensus algorithm: Cryptonight Proof-of-Work * Consensus algorithm: Cryptonight Proof-Of-Work
* Market capitalization: $5 million USD in mid-2014 * Market capitalization: $5 million USD in mid-2014
*Darkcoin* *Darkcoin*
Darkcoin was launched in January of 2014. Darkcoin implements anonymous currency using a re-mixing protocol for all transactions called DarkSend. Darkcoin is also notable for using 11 rounds of different hash functions (blake, bmw, groestl, jh, keccak, skein, luffa, cubehash, shavite, simd, echo) for the Proof-of-Work algorithm. Darkcoin was launched in January of 2014. Darkcoin implements anonymous currency using a re-mixing protocol for all transactions called DarkSend. Darkcoin is also notable for using 11 rounds of different hash functions (blake, bmw, groestl, jh, keccak, skein, luffa, cubehash, shavite, simd, echo) for the Proof-Of-Work algorithm.
* Block generation: 2.5 minutes * Block generation: 2.5 minutes
* Total currency: maximum 22 million DRK * Total currency: maximum 22 million DRK
* Consensus algorithm: Multi-algorithm Multi-round Proof-of-Work * Consensus algorithm: Multi-algorithm Multi-round Proof-Of-Work
* Market capitalization: $19 million USD in mid-2014 * Market capitalization: $19 million USD in mid-2014
=== Non-currency alt-chains === Noncurrency alt-chains
Alt-chains are alternative implementations of the blockchain design pattern, which are not primarily used as currency. Many include a currency, but the currency is used as a token for allocating something else, such as a resource or a contract. The currency, in other words, is not the main "point" of the platform, it is a secondary feature. Alt-chains are alternative implementations of the blockchain design pattern, which are not primarily used as currency. Many include a currency, but the currency is used as a token for allocating something else, such as a resource or a contract. The currency, in other words, is not the main "point" of the platform, it is a secondary feature.
==== Namecoin ==== Namecoin
Namecoin was the first "fork" of the bitcoin code. Namecoin is a de-centralized key-value registration and transfer platform using a blockchain. It supports a global domain name registry similar to the domain-name registration system on the Internet. Namecoin is currently used as an alternative Domain Name Service (DNS) for the root-level domain +.bit+. Namecoin can also be used to register names and key-value pairs in other namespaces, for storing things like email addresses, encryption keys, SSL certificates, file signatures, voting systems, stock certificates and a myriad of other applications. Namecoin was the first "fork" of the bitcoin code. Namecoin is a decentralized key-value registration and transfer platform using a blockchain. It supports a global domain-name registry similar to the domain-name registration system on the Internet. Namecoin is currently used as an alternative Domain Name Service (DNS) for the root-level domain +.bit+. Namecoin can also be used to register names and key-value pairs in other namespaces, for storing things like email addresses, encryption keys, SSL certificates, file signatures, voting systems, stock certificates, and a myriad of other applications.
The Namecoin system includes the namecoin currency (symbol NMC), which is used to pay transaction fees for registration and transfer of names. At current prices, the fee to register a name is 0.01 NMC or approximately 1 US cent. As in bitcoin, the fees are collected by Namecoin miners. The namecoin system includes the namecoin currency (symbol NMC), which is used to pay transaction fees for registration and transfer of names. At current prices, the fee to register a name is 0.01 NMC or approximately 1 US cent. As in bitcoin, the fees are collected by namecoin miners.
Namecoin's basic parameters are the same as bitcoin's: Namecoin's basic parameters are the same as bitcoin's:
* Block generation: 10 minutes * Block generation: 10 minutes
* Total currency: 21 million NMC by 2140 * Total currency: 21 million NMC by 2140
* Consensus algorithm: SHA256 Proof-of-Work * Consensus algorithm: SHA256 Proof-Of-Work
* Market capitalization: $10 million USD in mid-2014 * Market capitalization: $10 million USD in mid-2014
Namecoin's namespaces are not restricted, and anyone can use any namespace in any way. However, certain namespaces have an agreed upon specification so that when it is read from the blockchain, software knows how to read and proceed from there. If it is malformed, then whatever software you used to read from the specific namespace will throw an error. Some of the popular namespaces are: Namecoin's namespaces are not restricted, and anyone can use any namespace in any way. However, certain namespaces have an agreed-upon specification so that when it is read from the blockchain, software knows how to read and proceed from there. If it is malformed, then whatever software you used to read from the specific namespace will throw an error. Some of the popular namespaces are:
* +d/+ is the domain-name namespace for +.bit+ domains * +d/+ is the domain-name namespace for +.bit+ domains
* +id/+ is the namespace for storing person identifiers such as email addresses, PGP keys etc. * +id/+ is the namespace for storing person identifiers such as email addresses, PGP keys, etc.
* +u/+ is an additional, more structured specification to store identities (based on openspecs). * +u/+ is an additional, more structured specification to store identities (based on openspecs)
The Namecoin client is very similar to Bitcoin Core, as it is derived from the same source code. Upon installation, the client will download a full copy of the namecoin blockchain and then will be ready to query and register names. There are three main commands: The namecoin client is very similar to Bitcoin Core, because it is derived from the same source code. Upon installation, the client will download a full copy of the namecoin blockchain and then will be ready to query and register names. There are three main commands:
* +name_new+: Query or pre-register a name * +name_new+: Query or preregister a name
* +name_firstupdate+: Register a name and make the registration public * +name_firstupdate+: Register a name and make the registration public
* +name_update+: Change the details or refresh a name registration * +name_update+: Change the details or refresh a name registration
@ -309,14 +309,14 @@ $ namecoind name_new d/mastering-bitcoin
] ]
---- ----
The +name_new+ command registers a claim on the name, by creating a hash of the name with a random key. The two strings returned by +name_new+ are the hash and the random key (+a05555e0fc56c023+ in the example above) that can be used to make the name registration public. Once that claim has been recorded on the namecoin blockchain it can be converted to a public registration with the +name_firstupdate+ command, by supplying the random key: The +name_new+ command registers a claim on the name, by creating a hash of the name with a random key. The two strings returned by +name_new+ are the hash and the random key (+a05555e0fc56c023+ in the preceding example) that can be used to make the name registration public. Once that claim has been recorded on the namecoin blockchain it can be converted to a public registration with the +name_firstupdate+ command, by supplying the random key:
---- ----
$ namecoind name_firstupdate d/mastering-bitcoin a05555e0fc56c023 "{"map": {"www": {"ip":"1.2.3.4"}}}}" $ namecoind name_firstupdate d/mastering-bitcoin a05555e0fc56c023 "{"map": {"www": {"ip":"1.2.3.4"}}}}"
b7a2e59c0a26e5e2664948946ebeca1260985c2f616ba579e6bc7f35ec234b01 b7a2e59c0a26e5e2664948946ebeca1260985c2f616ba579e6bc7f35ec234b01
---- ----
The example above will map the domain name +www.mastering-bitcoin.bit+ to IP address 1.2.3.4. The hash returned is the transaction id that can be used to track this registration. You can see what names are registered to you by running the +name_list+ command: This example will map the domain name +www.mastering-bitcoin.bit+ to IP address 1.2.3.4. The hash returned is the transaction ID that can be used to track this registration. You can see what names are registered to you by running the +name_list+ command:
---- ----
$ namecoind name_list $ namecoind name_list
@ -335,17 +335,17 @@ $ namecoind name_list
---- ----
==== ====
Namecoin registrations need to be updated every 36,000 blocks (approximately 200 to 250 days). The +name_update+ command has no fee and therefore renewing domains in Namecoin is free. Third party providers can handle registration, automatic renewal and updating via a web interface, for a small fee. With a third-party provider you avoid the need to run a namecoin client, but you lose the independent control of a de-centralized name registry offered by Namecoin. Namecoin registrations need to be updated every 36,000 blocks (approximately 200 to 250 days). The +name_update+ command has no fee and therefore renewing domains in Namecoin is free. Third-party providers can handle registration, automatic renewal, and updating via a web interface, for a small fee. With a third-party provider you avoid the need to run a namecoin client, but you lose the independent control of a decentralized name registry offered by Namecoin.
==== Bitmessage ==== Bitmessage
Bitmessage is a bitcoin alt-chain that implements a de-centralized secure messaging service, essentially a server-less encrypted email system. Bitmessage allows users to compose and send messages to each other, using a bitmessage address. The messages operate in much the same way as a bitcoin transaction, but they are transient - they do not persist beyond 2 days and if not delivered to the destination node in that time, they are lost. Senders and recipients are pseudonymous, they have no identifiers other than a bitmessage address, but are strongly authenticated, meaning that messages cannot be "spoofed". Bitmessages are encrypted to the recipient and therefore the bitmessage network is resistant to holistic surveillance - an eavesdropper has to compromise the recipient's device in order to intercept messages. Bitmessage is a bitcoin alt-chain that implements a decentralized secure messaging service, essentially a server-less encrypted email system. Bitmessage allows users to compose and send messages to each other, using a bitmessage address. The messages operate in much the same way as a bitcoin transaction, but they are transient—they do not persist beyond two days and if not delivered to the destination node in that time, they are lost. Senders and recipients are pseudonymous—they have no identifiers other than a bitmessage address—but are strongly authenticated, meaning that messages cannot be "spoofed." Bitmessages are encrypted to the recipient and therefore the bitmessage network is resistant to holistic surveillance—an eavesdropper has to compromise the recipient's device in order to intercept messages.
==== Ethereum ==== Ethereum
Ethereum is a Turing-complete contract processing and execution platform based on a blockchain ledger. It is not a clone of bitcoin, but a completely independent design and implementation. Ethereum has a built-in currency, called _ether_, which is required in order to pay for contract execution. Ethereum's blockchain records _contracts_, which are expressed in a low-level, byte-code like, Turing-complete language. Essentially, a contract is a program that runs on every node in the Ethereum system. Ethereum contracts can store data, send and receive ether payments, store ether and execute an infinite range (hence Turing-complete) of computable actions, acting as de-centralized autonomous software agents. Ethereum is a Turing-complete contract processing and execution platform based on a blockchain ledger. It is not a clone of bitcoin, but a completely independent design and implementation. Ethereum has a built-in currency, called _ether_, which is required in order to pay for contract execution. Ethereum's blockchain records _contracts_, which are expressed in a low-level, byte-code like, Turing-complete language. Essentially, a contract is a program that runs on every node in the Ethereum system. Ethereum contracts can store data, send and receive ether payments, store ether, and execute an infinite range (hence Turing-complete) of computable actions, acting as decentralized autonomous software agents.
Ethereum can implement quite complex systems that are otherwise implemented as alt-chains themselves. For example, below is a Namecoin-like name registration contract written in Ethereum (or more accurately, written in a high-level language that can be compiled to Ethereum code): Ethereum can implement quite complex systems that are otherwise implemented as alt-chains themselves. For example, the following is a namecoin-like name registration contract written in Ethereum (or more accurately, written in a high-level language that can be compiled to Ethereum code):
[source,python] [source,python]
---- ----
@ -360,7 +360,7 @@ else:
=== Future of Currencies === Future of Currencies
The future of cryptographic currencies overall is even brighter than the future of bitcoin. Bitcoin introduced a completely new form of de-centralized organization and consensus that has spawned hundreds of incredible innovations. These inventions will likely affect broad sectors of the economy, from distributed systems science, to finance, economics, currencies, central banking, and corporate governance. Many human activities that previously required centralized institutions or organizations to function as authoritative or trusted points of control can now be de-centralized. The invention of the blockchain and consensus system will significantly reduce the cost of organization and coordination on large scale systems, while removing opportunities for concentration of power, corruption and regulatory capture. The future of cryptographic currencies overall is even brighter than the future of bitcoin. Bitcoin introduced a completely new form of decentralized organization and consensus that has spawned hundreds of incredible innovations. These inventions will likely affect broad sectors of the economy, from distributed systems science, to finance, economics, currencies, central banking, and corporate governance. Many human activities that previously required centralized institutions or organizations to function as authoritative or trusted points of control can now be decentralized. The invention of the blockchain and consensus system will significantly reduce the cost of organization and coordination on large-scale systems, while removing opportunities for concentration of power, corruption, and regulatory capture.