Sha256 mining algorithm
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.
when building bitcoin, Nakamoto wants bitcoin to be a decentralized currency, not only for use and trading, but also for mining. But it backfired. With the increasing value of cryptocurrency such as bitcoin, mining has become an instry. The competition is more and more fierce, and the pursuit of mining computing power is higher and higher. Therefore, from ordinary computer mining, ASIC mining machine and GPU mining machine have evolved
the algorithm of ASIC mining machine is almost sha256, while the algorithm of GPU mining is different. For example, the algorithm of BTG is equihash, and the algorithm of BCD is optimized x13. Although it is not absolute, it can be simply considered that the currency of sha256 algorithm is generally mined by ASIC mining machine. Other algorithms are basically using GPU miner. There are also exceptions. Scrypt's Leyte coin used to be mined by GPU miner, but later scrypt's algorithm was also conquered by ASIC chips, such as ant miner L3 +, which is the ASIC miner used to dig Leyte coin
ASIC miner refers to the miner that uses ASIC chip as the core of computing power. ASIC is the abbreviation of application specific integrated circuit, which is a kind of electronic circuit (chip) specially designed for a specific purpose. Some mining machinery factories have designed ASIC chips specially for computing the sha256 algorithm of bitcoin, and the mining machinery using them is ASIC mining machinery. Because ASIC chip is only built for specific computing, its efficiency can be much higher than that of CPU. For example, the current mainstream ant miner S9 is ASIC miner, which uses 189 ASIC chips, the computing power reaches 13.5th/s, and the power consumption is only 1350W. As a comparison, the computing power of gtx1080ti, the flagship computer graphics card, will not exceed 60mh / s even if it is optimized well. The difference is tens of thousands of times
GPU miner refers to the miner that uses GPU graphics card as the core of computing power. Cryptocurrencies such as Ethereum, bitcoin and diamond use graphics algorithms, so the speed of computing with graphics card will be the highest. Compared with ASIC miner, GPU miner is more well-known, because it is a computer with enhanced graphics card configurationthe purpose of GPU miner is to make money, so we should pursue the power consumption ratio and maximum profit, so we should pay attention to the cost performance. Generally, the medium and high-end positioning graphics cards, such as AMD rx560 and rx570, have high power consumption ratio, which is a good choice for GPU miner. While flagship cards such as gtx1080ti and AMD vega64 have the strongest single card performance, they are not cost-effective in terms of price and power consumption
in addition, the ASIC miner also has some exotic procts, such as the USB miner of burning cat, which is slightly larger than the U disk, and the power consumption is only 2.25w, which is the smallest bitcoin miner at present
< / blockquote >the above quoted digcoin.com - "Introction to mining machinery classification" has many professional terms. I hope it can help you, thank you
In fact, the mining calculation of bitcoin is to do math problems together. The problem stem is the transaction that needs to be recorded. By doing the problem, everyone grabs the bookkeeping right, and the miners can get system rewards and transaction fees. The feature of sha256 algorithm used in bitcoin is that it is easy to verify the known answers correctly, but it is very troublesome to get the answers, and it needs to try one by one. The miner who got the answer first was recognized by everyone as having snatched the right to keep accounts, and the reward was given to him. Let's continue to grab the bookkeeping right of the next question. In short, the significance of these calculations is only to ensure the stability and safety of the whole system, and there is no more significance
it is not comprehensive to regard bitcoin as a by-proct of computing. The generation and issuance of bitcoin, all the transactions and circulation in the bitcoin chain, and the stability of the bitcoin system are the purpose of computing and are integrated. Of course, in addition to maintaining the system, it does not proce other value and procts. This is also a black spot where bitcoin is accused of not being environmentally friendly and wasting resources. In general, bitcoin, as a milestone blockchain digital currency, is e to the huge value of a large amount of computing power investment and user trust. There is no doubt about that
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 pseudocode of SHA-1 algorithm is as follows:
(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 & gt; 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)))
2. The website selects a group of encryption algorithm and hash algorithm, and sends its identity information back to the browser in the form of certificate. The certificate contains the website address, encrypted public key, and the certificate authority and other information
3. After the browser obtains the website certificate, the browser should do the following work:
A) verify the validity of the certificate (whether the certificate issuing authority is legal, whether the website address contained in the certificate is consistent with the address being visited, etc.). If the certificate is trusted, a small lock will be displayed in the browser bar, otherwise the certificate will not be trusted
b) if the certificate is trusted or the user accepts an untrusted certificate, the browser will generate a string of random number passwords and encrypt them with the public key provided in the certificate
C) use the agreed hash algorithm to calculate the handshake message, use the generated random number to encrypt the message, and finally send all the previously generated information to the website< After receiving the data from the browser, the website should do the following operations:
A) use its own private key to decrypt the information, take out the password, use the password to decrypt the handshake message from the browser, and verify whether the hash is consistent with that from the browser
b) encrypt a handshake message with a password and send it to the browser
5. The browser decrypts and calculates the hash of the handshake message. If the hash is consistent with the hash sent by the server, the handshake process ends, and then all the communication data will be encrypted by the random password generated by the previous browser and the symmetric encryption algorithm.