wolfcoin is a Python-based mini-blockchain. The purpose of creating this project is to sharpen my understanding of blockchain's basic. The scope of the project covers hashing generating using the SHA-256 algorithm, and stacking blocks based on a previous hash. The output displays in local terminal setting, no transaction is made using this app.
🔥 Quick Hashing Display
⚡ Using SHA-256 algorithm to create instant hash
💥 Compacted within 50 Lines of code
🍱 Easy to read/follow code structure.
Third Party libraries are used in this project
| Package | Description |
|---|---|
hashlib |
SHA-256 Algorithm Core |
datetime |
Access real-time date |
The user needs to have Terminal/Bash installed, Python version in this project is 2.7.
🐍 Python 2.7
$ python wolfcoin.pyIn class Block: Creating a Block data structure that takes a few args including index, timestamp, a random data that could be anything and most importantly, a previous hash that the newly created block can build upon.
class Block:
def __init__(self, index, timestamp, data, previous_hash):
self.index = index
self.timestamp = timestamp
self.data = data
self.previous_hash = previous_hash
self.hash = self.hash_block()
def hash_block(self):
"""
Function Explain.
hash.update(arg) :Update the hash object with the string arg.
hash.hexdigest(arg) : Return the digest of the strings passed to the
update() method so far containing only hexadecimal digits.
"""
sha = hasher.sha256()
sha.update(str(self.index) +
str(self.timestamp) +
str(self.data) +
str(self.previous_hash))
return sha.hexdigest()In create_genesis_block(): When a blockchain is initiated, it needs to at least have one block, this function creates the very first block inside of the blockchain that has an arbitrary previous_hash since there is no previous_hash.
def create_genesis_block():
"""
Manually create the first block with
index zero and arbitary previous hash
"""
return Block(0, date.datetime.now(), "Genesis Block", "0")In def new_block(last_block): This function creates the rules on how a new block is created. In a nutshell, it gets previous_hash from the last element in the array, and update its own previous_hash to itself, so later when next block is created, it can read the current hash value.
def new_block(last_block):
"""
Create new block based on previous block
"""
this_index = last_block.index + 1
this_timestamp = date.datetime.now()
this_data = "Yo! I am block " + str(this_index)
this_hash = last_block.hash
return Block(this_index, this_timestamp, this_data, this_hash)In main: After creating necessary function, simply create a blockchain, add a genesis block, then loop over 20 times to create 20 blocks. Eventually, print them out, and we are done here.
# Create the genesis within Blockchain
blockchain = [create_genesis_block()]
previous_block = blockchain[0]
# Upper Bound of blocks
blocks_num = 20
# Loop and create 20 subsequent blocks
for i in xrange(0, blocks_num):
next_block = new_block(previous_block)
blockchain.append(next_block)
previous_block = next_block
print "Block #{} has been added to the blockchain!".format(next_block.index)
print "Hash: {}\n".format(next_block.hash)The blockchain application prints out each hash along with a relative index.
🌱 MIT 🌱
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