Virtual currency based on sha256 algorithm

1. In addition to bitcoin, there are many other virtual currencies in the virtual world< Liteoin (LTC) was released on October 7, 2011, and is currently the most valuable counterfeit currency, accounting for about 2% of BTC's market value. The current unit price is US $2.31, with a total currency value of US $38 million

this is also a distributed (decentralized) digital currency. Unlike the sha256 mining algorithm used by bitcoin, LTC adopts scrypt algorithm. Scrypt algorithm uses sha256 as its subroutine, and scrypt itself needs a lot of memory. Each hash is used as the seed of the input, and then it needs a lot of memory to store another pseudo-random sequence to generate the pseudo-random points of the sequence and output the hash value. In the mining of BTC (bitcoin), it is not enough to rely on simple graphics card mining (it takes about ten to dozens of days to dig a BTC with general configuration graphics card). The emergence of various expensive mining machines has raised the threshold for ordinary people to get BTC through mining, while LTC has certain advantages in using PC graphics card mining This passage comes from Zhihu.)

compared with BTC, litecain has made a little improvement in technology. If BTC is gold now, LTC is silver for the time being

the biggest advantage of litecoin is that it can confirm the authenticity faster. The virtual currency is designed and maintained by Charles Lee. Bitcoin transactions need to be verified, and the average verification time is more than 10 minutes. Most transaction websites need 1 hour to verify. The average transaction confirmation time of liteoin is 2.5 minutes. Developers claim that shortening the verification time increases the practicability of virtual currency. The bitcoin mining efficiency of customized machine and AMD GPU is the highest, making it almost unprofitable for miners using CPU mining. Litecain's mining excludes GPUs and custom processors, so it doesn't rely too much on a small number of professional miners

ppcoin

ppcoin (PPC) was released on August 19, 2012, which has improved the original technology of BTC. Use proof of make and add the concept of coin age

ppcoin is a bifurcated project of bitcoin, which aims to achieve energy efficiency and maintain the best performance of the original bitcoin as far as possible. The unit price of ppcoin is US $0.22 and the total currency value is US $4 million

ppcoin does not have a fixed upper limit of money supply, but it does not mean that ppcoin has obvious inflation compared with bitcoin. Bitcoin can be compared to gold. The annual inflation rate of gold is about 1-3%. Although gold has no known upper limit of money supply, we still know that it is a reliable scarce commodity

ppcoin has two types of casting: work certificate and equity certificate. The coinage rate of working proof is affected by Moore's law, which depends on the doubling of our working proof ability. What we all know is that Moore's law will eventually come to an end. By then, the ppcoin of inflation may be close to the gold level. The annual maximum inflation rate of certificate of equity is 1%. At the same time, ppcoin's transaction costs were destroyed to fight inflation. So on the whole, the coin design of ppcoin is still a very low inflation design in the future, which can be comparable with bitcoin<

ppcoin's reward is similar to lottery, which will determine the winning probability according to the number of ppcoin held by miners. Sunny king, one of the founders, said that their design is based on a new concept of long-term energy efficiency

terracoin

terracoin (TRC) was released on October 26, 2012, with a total currency of 42 million. The speed of each block is 2 minutes, slightly faster than LTC. There is not much special in technology, similar to the proction of BTC halved every four years

however, the operation team seems to have a strong business background and may be better than other bitcoins in circulation. The development of virtual currency is getting more and more attention. Now some teams with business background will accelerate the development of virtual currency

namecoin

namecoin is a distributed domain name system based on bitcoin technology. Its principle is the same as bitcoin. The first release date of this open source software is April 18, 2011

namecoin is generated from an original block which is different from bitcoin's main trading block. It uses a new blockchain, which is independent of bitcoin's blockchain. Because it is based on bitcoin, the security, distribution, robustness, encryption and migration of domain names are guaranteed mathematically. You can dig bitcoin and namecoin at the same time

this project was discussed and proposed by bitdns, which is mainly dissatisfied with the defects of DNS. The only top-level domain name of namecoin is. Bit. It costs namecoin to register a. Bit domain name

in addition, Q currency, Shanda currency, starting point currency and various online game currencies are also virtual currencies.

2. Bitcoin is a consensus network, contributing to a new payment system and a fully digital currency. It is the first decentralized peer-to-peer payment network, which is controlled by its users without a central management organization or middleman. From the user's point of view, bitcoin is much like Internet cash. Bitcoin can also be regarded as the most outstanding three style bookkeeping system

anyone can run software on specialized hardware and become a bitcoin miner. Mining software monitors transaction broadcast through P2P network and performs appropriate tasks to process and confirm these transactions. Bitcoin miners can earn transaction fees paid by users to speed up transaction processing and additional bitcoin issued according to fixed formula
new transactions need to be included in a block with mathematical workload proof before they can be confirmed. This kind of proof is hard to generate because it can only be generated by trying billions of calculations per second. Miners need to run these calculations before their blocks are accepted and rewarded. As more people start mining, the difficulty of finding effective blocks will be automatically increased by the network to ensure that the average time to find a block remains at 10 minutes. Therefore, the competition for mining is very fierce, and no indivial miner can control the content contained in the block chain
workload proof is also designed to rely on previous blocks, which forces the time sequence of block chain. This design makes it extremely difficult to cancel previous transactions, because the workload proof of all subsequent blocks needs to be recalculated. When two blocks are found at the same time, the miner will process the first block received, and once the next block is found, it will be transferred to the longest block chain. This ensures that the mining process maintains a global consistency based on processing capacity
bitcoin miners can neither increase their rewards by cheating, nor deal with the fraulent transactions that destroy the bitcoin network, because all bitcoin nodes will reject the blocks containing invalid data that violate the bitcoin protocol rules. Therefore, even if not all bitcoin miners can be trusted, the bitcoin network is still secure

sha256 is an encryption algorithm.

3.

1. Q coin

Q coin, referred to as QB, also known as QQ coin, Tencent Q coin, etc. Usually its exchange rate is 1q currency = 1 RMB, with Tencent paipai net transactions are generally 10% off

QB is a virtual currency launched by Tencent, which can be used to pay for QQ bank number, QQ member service and other services. Tencent q-coin, through the purchase of QQ card, telephone recharge, bank card recharge, network recharge, mobile phone recharge card, one card recharge card and other ways to obtain

The face value of QQ card is 10 yuan, 15 yuan, 30 yuan, 60 yuan, 100 yuan and 200 yuan respectively

there is another kind of electronic cryptocurrency, qqcoin, which is not related to each other

2. Litecoin

litecoin, abbreviated as LTC, currency symbol: Ł; It is a kind of network currency based on "peer-to-peer" technology. It is also an open source software project under MIT / X11 license. It can help users make instant payments to anyone in the world

lightcoin is inspired by bitcoin (BTC) and has the same implementation principle in technology. The creation and transfer of lightcoin is based on an open source encryption protocol and is not managed by any central organization

3, infinite coin

infinite coin (hereinafter referred to as IFC) is a new digital currency, which has more circulation advantages than bitcoin, and fills the short board of bitcoin in the field of commercial circulation and promoting commercial operation. The positioning of unlimited money is to serve the daily life of small transaction payment

one transaction of infinite coin needs three confirmations, each confirmation takes three seconds, and the transaction confirmation speed is very fast. Because bitcoin transaction needs 6 confirmations, which takes about 1 hour, and lightcoin transaction takes 15 minutes, infinite coin is used in daily common transactions, which is more practical

infinite coin was released on June 5, 2013. Based on scrypt POW algorithm. A block is generated in 30 seconds. In the initial block, there are 524288 infinite coins in each block. After that, for every 86400 blocks generated, the number of coins in the block is halved, with a total of 90.6 billion. The difficulty of mining is adjusted every hour

Quark coin is not the currency in real life, it exists safely in the computer of global network

quark network is protected by six most advanced encryption algorithms to ensure that it can become a digital ledger. The whole network uses each of the six functions to generate a proof of work, and the coin maker must "verify" these transactions to ensure that each coin increase is real and effective

only regular computer can participate in ensuring that it can maintain a highly secure peer-to-peer network, which makes it more decentralized

quark coins can only be g up through the CPU of regular computers. In the first 36 weeks, a total of 247605120 quark coins will be g out. Since March 30, 2014, the annual quark coins set at 1050000 can enter the market through "digging", and the block reward will never be less than one, which is currently two

Zetacoin is an open-source digital currency based on SHA-256 algorithm. The initial coin mining is 160 million coins, and the subsequent annual inflation is a better incentive, To keep the hash of the network is not pure transaction cost

The total number of

zetacoin is 160 million, 1000 zets per block and half of 80640 zets per block

4. Litecoin

litecoin (LTC), released on October 7, 2011, is the most valuable counterfeit coin at present, accounting for about 2% of BTC's market value. The current unit price is US $2.31, with a total currency value of US $38 million

this is also a distributed (decentralized) digital currency. Unlike the sha256 mining algorithm used by bitcoin, LTC adopts scrypt algorithm. Scrypt algorithm uses sha256 as its subroutine, and scrypt itself needs a lot of memory. Each hash is used as the seed of the input, and then it needs a lot of memory to store another pseudo-random sequence to generate the pseudo-random points of the sequence and output the hash value. In the mining of BTC (bitcoin), it is not enough to rely on simple graphics card mining (it takes about ten to dozens of days to dig a BTC with general configuration graphics card). The emergence of various expensive mining machines has raised the threshold for ordinary people to get BTC through mining, while LTC has certain advantages in using PC graphics card mining This passage comes from Zhihu.)

compared with BTC, litecain has made a little improvement in technology. If BTC is gold now, LTC is silver for the time being

the biggest advantage of litecoin is that it can confirm the authenticity faster. The virtual currency is designed and maintained by Charles Lee. Bitcoin transactions need to be verified, and the average verification time is more than 10 minutes. Most transaction websites need 1 hour to verify. The average transaction confirmation time of liteoin is 2.5 minutes. Developers claim that shortening the verification time increases the practicability of virtual currency. The bitcoin mining efficiency of customized machine and AMD GPU is the highest, making it almost unprofitable for miners using CPU mining. Litecain's mining excludes GPUs and custom processors, so it doesn't rely too much on a small number of professional miners

ppcoin

ppcoin (PPC) was released on August 19, 2012, which has improved the original technology of BTC. Use proof of make and add the concept of coin age

ppcoin is a bifurcated project of bitcoin, which aims to achieve energy efficiency and maintain the best performance of the original bitcoin as far as possible. The unit price of ppcoin is US $0.22 and the total currency value is US $4 million

ppcoin does not have a fixed upper limit of money supply, but it does not mean that ppcoin has obvious inflation compared with bitcoin. Bitcoin can be compared to gold. The annual inflation rate of gold is about 1-3%. Although gold has no known upper limit of money supply, we still know that it is a reliable scarce commodity

ppcoin has two types of casting: work certificate and equity certificate. The coinage rate of working proof is affected by Moore's law, which depends on the doubling of our working proof ability. What we all know is that Moore's law will eventually come to an end. By then, the ppcoin of inflation may be close to the gold level. The annual maximum inflation rate of certificate of equity is 1%. At the same time, ppcoin's transaction costs were destroyed to fight inflation. So on the whole, the coin design of ppcoin is still a very low inflation design in the future, which can be comparable with bitcoin<

ppcoin's reward is similar to lottery, which will determine the winning probability according to the number of ppcoin held by miners. Sunny king, one of the founders, said that their design is based on a new concept of long-term energy efficiency

terracoin

terracoin (TRC) was released on October 26, 2012, with a total currency of 42 million. The speed of each block is 2 minutes, slightly faster than LTC. There is not much special in technology, similar to the proction of BTC halved every four years

however, the operation team seems to have a strong business background and may be better than other bitcoins in circulation. The development of virtual currency is getting more and more attention. Now some teams with business background will accelerate the development of virtual currency

namecoin

namecoin is a distributed domain name system based on bitcoin technology. Its principle is the same as bitcoin. The first release date of this open source software is April 18, 2011

namecoin is generated from an original block which is different from bitcoin's main trading block. It uses a new blockchain, which is independent of bitcoin's blockchain. Because it is based on bitcoin, the security, distribution, robustness, encryption and migration of domain names are guaranteed mathematically. You can dig bitcoin and namecoin at the same time

this project was discussed and proposed by bitdns, which is mainly dissatisfied with the defects of DNS. The only top-level domain name of namecoin is. Bit. It costs namecoin to register a. Bit domain name.

5. The latest release of Ryle coin is the core algorithm of crypt, which also tends to mine CPU

6. There are mainly two kinds of bitcoin algorithms, which are elliptic curve digital signature algorithm and sha256 hash algorithm

elliptic curve digital signature algorithm is mainly used in the generation process of bitcoin public key and private key, which is the cornerstone of bitcoin system. SHA-256 hash algorithm is mainly used in the workload proof mechanism of bitcoin

the principle of bitcoin generation is the special solution generated by complex operation, and mining is the process of finding the special solution. However, the total number of bitcoin is only 21 million, and with the continuous mining of bitcoin, the more difficult it will be to proce bitcoin, and the cost of acquiring bitcoin may be higher than the price of bitcoin itself

the bitcoin block consists of a block header and the transaction list contained in the block. The size of the block header is 80 bytes, which is composed of 4-byte version number, 32 byte hash value of the previous block, 32 byte Merkle root hash, 4-byte timestamp (current time), 4-byte current difficulty value and 4-byte random number. A block header with a fixed length of 80 bytes is the input string used to prove the workload of bitcoin. Constantly change the random number in the block header, that is, the value of nonce, and do double sha256 operation on the block header after each change, and compare the result value with the target value of the current network. If it is less than the target value, the problem is solved successfully, and the workload is proved to be complete

the essence of bitcoin is actually the unique solution of a set of equations generated by a bunch of complex algorithms. Bitcoin is the first distributed virtual currency in the world, which has no specific distribution center. The network of bitcoin is composed of all users, because there is no center to ensure the security of data.

7. SHA-256 is the encryption algorithm used by some columns of bitcoin digital currency. However, it uses a lot of computing power and processing time, forcing miners to set up mining pools to obtain benefits.

8. You are talking about the sha256 signature algorithm. The security factor is good. It is an international standard encryption algorithm. Many transparent encryption software on the market now use this encryption algorithm. Destroying the signature and modifying the data will make the encryption software unusable. The red line privacy protection system that I know about for free encryption software uses this signature algorithm.

9. Sha family
Sha (secure hash algorithm) is a series of cryptographic hash functions designed by National Security Agency (NSA) and published by National Institute of standards and Technology (NIST). The first member of the family officially named Sha was published in 1993. However, it has now been given an informal name sha-0 to avoid confusion with its successors. Two years later, SHA-1, the successor of the first Sha, was released. There are also four variants that have been released to enhance the scope of output and to change some minor designs: sha-224, SHA-256, sha-384, and sha-512 (sometimes referred to as SHA-2)<
sha-0 and SHA-1
the algorithms originally specified were published in 1993, which are called secure hash standard, FIPS pub 180. This version is now often called & quot; SHA-0" It was withdrawn by NSA soon after its release, and released in 1995 as a revised version of FIPS pub 180-1 (commonly known as & quot; SHA-1") replace. According to NSA, it fixed an error in the original algorithm that would rece password security. However, NSA does not provide any further explanation or proof that the error has been corrected. In 1998, in an attack on sha-0, it was found that this attack was not applicable to SHA-1 - we don't know if this is the error found by NSA, but it may indicate that this correction has improved the security. SHA-1 has been closely examined by the public password community, but it has not been found to be unsafe. It is now considered safe
sha-0 and SHA-1 will generate a 160 bit digest from a message with a maximum size of 2 ^ 64 bits, and then encrypt it based on the similar principle of Ronald L. Rivest, Professor of MIT who designed MD4 and MD5 message digest algorithms<
Cryptanalysis of sha-0
on crypto 98, two French researchers demonstrated an attack on sha-0 (chabaud and joux, 1998): hash collision can be found when the complexity is 2 ^ 61; Less than 2 ^ 80 is an ideal hash function of the same size
in 2004, Biham and Chen discovered the approximate collision of sha-0 - two messages can hash out the same value; In this case, 142 and 160 bits are the same. They also found that sha-0 dropped to 62 bits after 80 full collisions
on August 12, 2004, joux, carribault, lemuet and jalby announced the hash collision of the complete sha-0 algorithm. This is the result of the attack of chabaud and joux. The collision was found to be 2 ^ 51, and it took about 80000 CPU hours to work on a supercomputer with 256 Itanium 2 processors< On August 17, 2004, Wang, Feng, Lai, and Yu announced the preliminary results of attacking MD5, sha-0, and other hash functions at the rump meeting of crypto 2004. Their attack on sha-0 is as complex as 2 ^ 40, which means that their attack results are better than those of joux and others. A brief summary of the rump meeting can be found here, and their discussions in sci.crypt, for example, suggest that people planning to use SHA-1 as a new cryptosystem need to reconsider
longer variants
NIST has released three additional Sha variants, each with a longer message digest. They are named by adding their summary length (in bits) after their original name: & quot; SHA-256", & quot; SHA-384" And & quot; SHA-512" They were published in the draft of FIPS pub 180-2 in 2001, and then passed the review and comments. FIPS pub 180-2, including SHA-1, was released as an official standard in 2002. These new hash functions have not been tested in detail by the public password community like SHA-1, so their password security is not widely trusted. In February 2004, a change notice of FIPS pub 180-2 was issued, and an additional variant was added; SHA-224"， The key length required for double key 3DES is defined
Gilbert and handschuh (2003) studied new varieties and found no weaknesses<
shad
shad function is a simple restatement of the same Sha function:
shad-256 (m) = SHA-256 (SHA-256 (m)). It overcomes the problem of extended length attacks
applications
SHA-1, sha-224, SHA-256, sha-384 and sha-512 are all used by the U.S. federal government, which needs secure hash algorithms. They also use other cryptographic algorithms and protocols to protect sensitive unclassified data. FIPS pub 180-1 also encourages private or commercial organizations to use SHA-1 encryption. Fritz chip will probably use SHA-1 hash function to realize digital rights management on personal computers
the first to promote the publication of secure hash algorithm is the combined digital signature standard
Sha hash function has been used as the basis of shacal block cipher algorithm<
description of SHA-1
the following is the pseudo code of SHA-1 algorithm:
(initialize variables:)
A = H0 = 0x67452301
b = H1 = 0xefcdab89
C = h2 = 0x98badcfe
d = H3 = 0x10325476
e = H4 = 0xc3d2e1f0
(pre processing:)
paddedmessage = (message) append 1
while length (paddedmessage) mod 512 & lt; > 448:
paddedmessage = paddedmessage append 0
paddedmessage = paddedmessage append (length(message) in 64-bit format)
(Process the message in successive 512-bit chunks:)
while 512-bit chunk(s) remain(s):
break the current chunk into sixteen 32-bit words w(i), 0 <= i <= 15
(Extend the sixteen 32-bit words into eighty 32-bit words:)
for i from 16 to 79:
w(i) = (w(i-3) xor w(i-8) xor w(i-14) xor w(i-16)) leftrotate 1
(Main loop:)
for i from 0 to 79:
temp = (a leftrotate 5) + f(b,c,d) + e + k + w(i) (note: all addition is mod 2^32)
where:
(0 <= i <= 19): f(b,c,d) = (b and c) or ((not b) and d), k = 0x5A827999
(20 <= i <= 39): f(b,c,d) = (b xor c xor d), k = 0x6ED9EBA1
(40 <= i <= 59): f(b,c,d) = (b and c) or (b and d) or (c and d), k = 0x8F1BBCDC
(60 <= i <= 79): F (B, C, d) = (b XOR C XOR d), k = 0xca62c1d6
e = d
d = C
C = B leftrotate 30
b = a
A = temp
H0 = H0 + a
H1 = H1 + B
h2 = H2 + C
H3 = H3 + d
H4 = H4 + e
digest = hash = H0 append H1 append H2 append H3 append H4
note: FIPS pub 180-1 shows the concept of, The efficiency can be improved by using the following formula:
(0 & lt= i <= 19): f(b,c,d) = (d xor (b and (c xor d)))
(40 <= i <= 59): f(b,c,d) = (b and c) or (d and (b or c)))