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Primecoin Logo.png
Primecoin logo
Central bankNone, the primecoin peer-to-peer network regulates and distributes through consensus in protocol.
Date of introduction7 July 2013[1]
InflationLimited release, production rate before this limit re-evaluated with the production of every block (at a rate of approximately 1 block per minute) based on the difficulty with which primecoins are produced.
Page Template:Nobold/styles.css has no content. 0.001mXPM (millicoin)
Page Template:Nobold/styles.css has no content. 0.000001μXPM (microcoin)
Page Template:Nobold/styles.css has no content. 0.00000001Smallest unit
PluralPrimecoin, primecoins

Primecoin (sign: Ψ; code: XPM) is a peer-to-peer open source cryptocurrency that implements a unique scientific computing proof-of-work system.[2] Primecoin's proof-of-work system searches for chains of prime numbers.[2] Primecoin was created by a person or group of people who use the pseudonym Sunny King. This entity is also related with the cryptocurrency Peercoin.[3][4] The Primecoin source code is copyrighted by a person or group called “Primecoin Developers”, and distributed under a conditional MIT/X11 software license.[5]

Primecoin has been described as the main cause of spot shortages of dedicated servers due to the fact that at the time it was only possible to mine the currency with CPUs.[1][6] For the same reason, Primecoin used to be the target of malware writers.[7][8]

For some time it seemed nearly impossible to implement Primecoin's unique mining proof-of-work on GPU hardware, but on 29th of March 2014 the first GPU miner became publicly available.

Currently there are many GPU miners available both in solo and pool mining variations.


When comparing Primecoin with today's most widely spread cryptocurrency called Bitcoin some notable differences are:

Scarcity is governed by the nature of prime number distribution
Almost all cryptocurrencies in existence define their scarcity properties merely by set of predefined values in source code, whereas scarcity of Primecoin is based purely on a relationship of a simple function and mathematical property of natural occurrence of prime chains in the set of whole numbers that are.
No predefined ultimate number of coins
Instead of having hard-set ultimate number of coins in its code like many other alternative cryptocurrencies, number of Primecoins released per block is always equal to 999 divided by the square of the difficulty.[9] There has been some attempts at approximating this number. The number of Primecoins that will be mined will be determined by the progress of its adaptation by the mining community, improvements that will be done to the mining algorithms and ultimately by Moore's law.
Difficulty adjustment is more frequent
Primecoin protocol adjusts its difficulty slightly after every block. The difficulty change that occurs each block is targeted at achieving target of one new block created once per minute. [9] As comparison the Bitcoin protocol adjusts its difficulty every 2016 blocks, or approximately every two weeks.
Faster transaction confirmations
Since Primecoin blocks are generated 8 to 10 times as fast as Bitcoin blocks on average, Primecoin transactions are confirmed approximately 8 to 10 times as fast.[9]

Proof-of-work system

Primecoin uses the finding of prime chains composed of Cunningham chains and bi-twin chains for proof-of-work, which can lead to useful byproducts.[2][9]

The system is designed so that the work is efficiently verifiable by all nodes on the Primecoin network.[2] To meet this requirement, the size of the prime numbers in the system cannot be too large.[2] The Primecoin proof-of-work system has the following characteristics:

  • Primecoin's work takes the form of prime number chains.[9]
  • Finding the prime number chains becomes exponentially harder as the chain length is increased.[2]
  • Verification of the reasonably sized prime number chains can be performed efficiently by all network nodes.[2]
  • Mersenne primes are precluded due to their extremely large size.[2]
  • Three types of prime number chains are accepted as proof-of-work:[9]
  1. Cunningham chain of the first kind.
  2. Cunningham chain of the second kind.
  3. Bi-twin chain.

Other cryptocurrencies including Bitcoin commonly use a Hashcash type of proof-of-work based on SHA-256 hash calculations, which are of no value beyond its own economy.[2][9]

See also


  1. 1.0 1.1 Clark, Jack (2013-07-16). "Virtual currency speculators shut down cloud". The Register. Retrieved 2014-02-02.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 King, Sunny (pseudonym) (2013-07-07) (PDF). Primecoin: Cryptocurrency with Prime Number Proof-of-Work. Retrieved 2013-11-07. 
  3. Bradbury, Danny (2013-01-02). "Why are so many digital currency players anonymous?". CoinDesk. Retrieved 2014-03-14.
  4. Gilson, David (2013-07-10). "New currency Primecoin searches for prime numbers as proof of work". CoinDesk. Retrieved 2014-02-08.
  5. Primecoin Developers (2013-07-25). "Primecoin High Performance 0.1.1 BETA README" (Text file). Primecoin High Performance – Browse /0.1.1-hp8 at mikaelh2. Retrieved 2014-02-11.
  6. Miller, Rich (2013-12-17). "Currency Miners Cause Spot Shortages of Dedicated Servers". Data Center Knowledge. Retrieved 2013-12-18.
  7. Muncaster, Phil (2014-01-17). "Bitcoin's so over. We're mining Primeco... Oh SNAP, my box is a ZOMBIE!". The Register. Retrieved 2014-02-02.
  8. Goodin, Dan (2013-12-17). "What a successful exploit of a Linux server looks like". Ars Technica. Condé Nast. Retrieved 2014-02-02.
  9. 9.0 9.1 9.2 9.3 9.4 9.5 9.6 Buterin, Vitalik (2013-07-08). "Primecoin: the cryptocurrency whose mining is actually useful". Bitcoin Magazine. Coin Publishing Ltd.

External links