An implementation of the blockchain. Educational purposes mostly.
I still don't get bitcoin
Image if keeping your car idling 24/7 produced solved Sudokus you could trade for heroin
A blockchain is an immutable, sequential chain of records called Blocks.
They contain any data, but more importantly they are chained together using hashes.
If a hash is corrupted by an attacker than all subsequent blocks will have incorrect hashes.
To create/mine new Blocks, the Proof of Work algorithm must be solved. This algorithm discovers a number
which solves a problem; it must be difficult to solve but easy to verify computationally.
To ensure consensus amongst nodes, we make the rule that the longest valid chain is authoritative.
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I have a series of transaction data: sender, recipient, & the amount transferred. These transaction entries are stored in a Block. A SHA-256 hash is created from this serialised block; thus, any changes to the Block will change the Block's hash. This prevents modifications to Blocks because it will invalidate the hash.
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What determines Block validity?
The proof-of-work algorithm intends to be hard to solve but easy to verify; e.g. Sudoku.
In this example, the task is to find the proof string p such that the hash of the concatenation of ( p' p ), where p' is the previous Block's proof, provides a hash with four leading zeros.
Computational difficulty can scale with the number of leading zeros required. -
How do all the interconnected parts work?
A node has a record of the Blockchain from consensus with other nodes. Transactions are sent to the node and stored for the node's next Block. Once the node solves the proof-of-work algorithm, it may attach a transaction of "new unit of currency" to it's transaction ID. It then hashes it's contents and appends to the Blockchain.
N.B. Crypto's act differently; transactions require consensus, the blockchain updates every ten minutes, etc.
Either python3 app.py or make docker.
Then use PostMan or equivalent to make HTTP requests. See app.py for API.