Proof of source of bitcoin funds

1. In the 1980s, a group of talented programmers explored this problem in the password mail group. In 1982, David Chaum proposed an untraceable cryptography network payment system. Eight years later, he extended this idea to cryptology anonymous cash system, namely ecash.
2 in 1998, Wei Dai's paper elaborated an anonymous and distributed e-cash system: B-money. At the same time, Nick Szabo invented bitgold and put forward the workload proof mechanism. Users solve mathematical problems competitively, and then publish the results in series with encryption algorithm to build a property rights authentication system. Hal Finney improved the mechanism as a "reusable workload proof"
3 on the basis of previous work, in 2008, the little-known "Nakamoto Tsung" published "bitcoin: a peer-to-peer cash payment system" in the cryptography mailing list of metzdowd.com. On January 3, 2009, bitcoin network was born, and Nakamoto himself released the first version of open source bitcoin client
since then, the monetary history of mankind has opened a new page.

2.

Transaction mode of bitcoin

bitcoin is e-cash similar to e-mail, and both parties need "bitcoin wallet" similar to e-mail and "bitcoin address" similar to e-mail address. Just like sending and receiving e-mail, the remitter pays bitcoin directly to the other party through a computer or smart phone according to the recipient's address. The following table lists some websites that download bitcoin wallets and addresses for free

a bitcoin address is a string of about 33 characters long, consisting of letters and numbers, always starting with 1 or 3, such as & quot& quot; Bitcoin software can generate address automatically, and it doesn't need to exchange information online, so it can be offline. More than 2 bitcoin addresses are available. Figuratively speaking, there are about two grains of sand in the world. If there is an earth in each grain of sand, then the total number of bitcoin addresses far exceeds the number of all the sand on all these "earths"

the bitcoin address and private key appear in pairs, and their relationship is just like the bank card number and password. A bitcoin address is like a bank card number, which records how much bitcoin you have on it. You can generate bitcoin address at will to store bitcoin. When each bitcoin address is generated, a corresponding private key of the address will be generated. This private key proves that you have ownership of the bitcoin at that address. We can simply understand the bitcoin address as the bank card number, and the private key of the address as the password of the corresponding bank card number. Only when you know the bank password can you use the money on the bank card number. Therefore, please keep your address and private key when using bitcoin wallet

after the transaction data of bitcoin is packaged into a "data block" or "block", the transaction is initially confirmed. When a block is linked to a previous block, the transaction is further confirmed. After six block confirmations in a row, the transaction was irreversibly confirmed. Bitcoin P2P stores all transaction history in a "blockchain.". The blockchain continues to extend, and once new blocks are added to the blockchain, they will not be removed. Blockchain is actually a distributed database composed of a group of scattered client nodes and all participants, which is a record of all bitcoin transaction history. Nakamoto predicts that when the amount of data increases, users hope that not all the data will be stored in their own nodes. In order to achieve this goal, he uses the hash function mechanism. In this way, the client will be able to automatically eliminate those parts that it will never use, such as some very early bitcoin transactions

3. We know the process of information computing hash packing: transaction record, time, account number, last hash value. We also know that all calculation and storage need to consume computer resources. In Nakamoto's design, the completion of bookkeeping can be rewarded with bitcoin by the system, which is also the process of issuing bitcoin. Therefore, bookkeeping becomes mining
bookkeeping
because bookkeeping is a reward, each time you can add a certain number of bitcoin for yourself, so everyone is competing for bookkeeping, which of course leads to a problem: when there is inconsistency in bookkeeping, the system introces workload proof to solve the problem, and the rules are as follows:
1. In a period of time, only one person can succeed in bookkeeping
2. Obtain the unique bookkeeping right by solving the cryptography problem
3. Other nodes the bookkeeping results
but before the workload proof, The accounting node will do the following preparatory work:
1. Collect the original transaction information that has not been recorded in the broadcast
2. Check whether the payment address in each transaction information has enough balance
3. Verify whether the transaction has the correct signature
4. Package and record the verified transaction information
5. Add a reward transaction: add 12.5 to your address Bitcoin
if you succeed in competing for bookkeeping rights, you can get a reward of 12.5 bitcoin
workload proof
the hash value of the previous block and the current account page information will be hashed together as the original information in each bookkeeping. In order to ensure that only one person can keep accounts around 10 minutes, we have to improve the difficulty of keeping accounts. The results of hash must start with several zeros. In order to satisfy the condition, hash is to introce a random number variable
denoted by pseudo code:
1. Hash (last hash value, transaction record set) = 456635bcd
2. Hash (last hash value, transaction record set, random number) = 0000afd635bcd
if you change part of the original information of hash, the hash value will also change continuously. Therefore, when you run hash, the value of random number will change continuously, A random number can always be found so that the result of hash starts with several zeros. The node that finds the random number first obtains the unique bookkeeping right
verification
after the node successfully finds the hash value, it will broadcast and package the block to the whole network immediately, and the node of the network will verify it after receiving the broadcast. If the verification is passed, it indicates that a node has successfully decrypted, it will not compete for the current block, but will choose to accept the block and record it in its own account book for the next round of competitive guessing. Only the fastest decrypted block in the network will be added to the ledger, and other nodes will to ensure the uniqueness of the whole ledger
If a node has cheating behavior, it will cause the node of the network to fail the verification, give up its packaged block directly, and cannot be recorded in the general ledger, then the consumption cost of the cheating node will be in vain. Therefore, miners consciously abide by the consensus protocol of bitcoin system, and ensure the security of the whole system
it's like you go to the construction site to move bricks. After moving bricks for one day, the contractor asks you how can you prove that you move bricks for one day?

4. Hash algorithm maps any length of binary value to a fixed length of smaller binary value, which is called hash value. Hash value is a unique and compact numerical representation of a piece of data. If you hash a piece of plaintext and change only one letter of the paragraph, subsequent hashes will proce different values.

5. Nice University's DDE project is good. The full name of nice University's DDE is nice University's doctor of blockchain and digital economy management. He belongs to the direction of blockchain and digital economy management of University of nice DBA
DDE of nice University (Doctor of blockchain and digital economy management of nice University) is the first doctoral program of digital economy in China. It follows the current tide of digital economy and blockchain era, accurately grasps the essence and development direction of digital economy, and deeply participates in China's blockchain era and economic reform process. Cultivate talents in short supply in the job market such as blockchain, big data and artificial intelligence
DDE of nice University (Doctor of blockchain and digital economy management of nice University) Shanghai enrollment point: Xiejin ecation Xipu International College 19th floor D, Shentong Shentong Information Plaza, 55 Huaihai West Road, Shanghai.

6. The client does not need to know the real random number. The client (also the system) actually wants the hash value of the "random number" to be less than a certain value
for example, the value of sha256 of 041665464 (random number) is: (hexadecimal) 0ffffffff... (if)
it does not meet the requirement of less than 00ffffff, so it is not a block
the value of sha256 of 041665465 (random number) is: (hexadecimal) 000ffffff... (if)
it meets the requirement of less than 00ffffff, so it is a block

in fact, it is very difficult to find a random number less than a hash value, which is the principle of workload proof
the value to be less than (00ffff...) is variable (difficulty), which varies with time and computing power.

7. Anti counterfeiting
like the theory of evolution, the main chain is obtained through continuous screening consensus, and the accumulated amount of computation is high. If you want to forge the main chain, you must pay a higher price (half of the computing power of the whole network). For example, the electricity consumption of bitcoin mining is equal to that of Singapore. You have to pay half of Singapore's electricity if you want to fake it