The technical cornerstones of blockchain mainly include :

  • SHA256 Hash 

  • Public key cryptography

  • Workload certification mechanism

(1)SHA256 Hash

The core hash algorithm used by blockchain is  SHA256, The calculated value cannot be decrypted back to the original content , It's one-way , And no matter how much of the original content , The length of the result is fixed , for example :

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You can see , Even if the difference in the original content is very small , The results are very different .

SHA256 It can be collision free , That is, no input x≠y, however H(x)=H(y)

SHA256 There will be 2^256 Seed output , If we do 2^256+1 Time input , Then there must be a collision , We can calculate that , Suppose a computer runs at a rate of 10000 Time to hash , To pass 10^27 Years to complete 2^128 Secondary hash , So the chance of a collision is extremely small .

(2) Public key cryptography

This encryption technology helps users create a public key and a private key , Public key can be shared with others , The private key needs to be kept in secret .

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If Chandler to Joey Transfer some bitcoin , This deal will include 3 Some information :

  • Joey My bitcoin address (Joey The public key )

  • The number of bitcoins traded

  • Chandler My bitcoin address (Chandler The public key )

All of this data and encrypted digital signatures are sent over the network for verification . The digital signature is Chandler His bitcoin address and his joey The combined hash value of the number sent , This digital signature is encrypted by the private key .

When the miners receive this data , He'll verify it , Will do two jobs at the same time :

  1. Put all unencrypted data ( Transaction amount 、 Two people's public keys ) Put it in the hash algorithm , Get a hash value ( Such as Hash1)

  2. Use Chandler The public key decrypts the digital signature , Get a hash value ( Such as Hash2)

If Hash1 And Hash2 identical , So it's a legal deal .

(3) Proof of workload

Everyone in the blockchain owns the ledger equally , So who will add blocks to the blockchain ? How to trust this person ?

So , With Proof of workload POW The concept , It can be understood as solving a complicated problem , It takes a lot of calculation , The people who do this work are called “ The miners ”. The job of these miners is to validate transactions and solve complex mathematical problems associated with creating blocks .

Each block has a hash value , It's a combination of data , Include :

  1. Hash value of the previous block

  2. Hash value of transaction data

  3. nonce

The final hash value must be in the specified number of 0 At the beginning .

for instance , Given a basic string  Hello, world!, Our workload requirement is : You can add a string called nonce The integer value , Modify the changed string SHA256 Hash operation , If you get a hash result ( With 16 In the form of base ) In order to "0000" At the beginning , Then the verification is passed .

In order to achieve this goal of workload proof . We need to keep increasing nonce value , To get a new string for SHA256 Hash operation . According to this rule , We need to go through 4251 It takes two calculations to find just before 4 Position as 0 Hash of .

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Who found this first nonce Who is the winning miner , You can add his blocks to the blockchain , Everyone can verify it , If it's right, update their blockchain , Continue to calculate the next block .

Summary

I hope that through the above brief introduction , It can give you a general understanding of blockchain technology , After that, the application details of blockchain technology will be introduced in detail .