Build your own Mini-Blockchain!
Lesson 1 of 1
  1. 1
    Representing Transactions
    In this lesson, you’ll build a small blockchain of your own in Python! This lesson assumes a familiarity with Python syntax, functions, loops, importing libraries, and constructing classes, but the…
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  2. 2
    Creating Blocks
    Now let’s think of a way to represent a block in Python. We could create a bigger dictionary and store our data inside this dictionary. But since blocks can be represented as objects, let’s create …
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  3. 3
    Hashing and SHA-256
    Before we create a more dynamic blockchain, let’s learn how to use a hash function in Python. Specifically, we will be using the SHA-256 hash function which can be easily imported in Python. We…
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  4. 4
    Generating Block Hashes
    Block hashes are used to uniquely identify and maintain the integrity of each block. The SHA-256 algorithm is used to generate the hash of the block using the timestamp, data, and previous hash — t…
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  5. 5
    Creating the Blockchain Class
    Each computer participant has their own copy of the blockchain. Ideally, each copy of the blockchain should have the same properties and functionality to add and validate blocks. We can represent…
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  6. 6
    Adding Blocks to the Blockchain
    Now that we have everything in place, let’s begin adding blocks to the blockchain.
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  7. 7
    Checking for a Broken Chain
    Hashing helps to maintain the integrity of the blockchain. In this exercise, we will see this in action. Let’s write a .validate_chain() method that checks to see if blocks are linked to each other…
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  8. 8
    Hacking the Chain
    Now we can use the code in our previous exercise to spot a broken link. Let’s try tampering with the contents of the block and see how that creates a mismatch between hash values.
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  9. 9
    Nonce and Proof-of-Work
    Let’s review the concepts of nonce and proof of work. In this exercise, we will implement an example that demonstrates the difficulty of the math problem that helps protect the blockchain from pote…
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  10. 10
    Implementing Proof-of-Work
    Now that we’ve seen a simple example of Proof-of-Work, let’s integrate it into our blockchain! Complete the proof_of_work() method inside the Blockchain class.
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  11. 11
    Adding Blocks to the Chain Securely
    Now that we have implemented our Proof-of-Work method, we can now work on adding new blocks securely.
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  12. 12
    Blockchain Summary
    Congratulations! You have completed all the steps required to build a basic blockchain! In this exercise, we will bring the key parts together to review what we have built so far. *Note: * The b…
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