Why security prevents financial loss in Blockchain / Solidity - See It in Action

Why Security Prevents Financial Loss in Blockchain

📖 Scenario: Imagine you are building a simple blockchain system that keeps track of transactions. Each transaction has a sender, receiver, and amount. To keep the system safe, you want to check if a transaction is valid before adding it to the blockchain. Invalid transactions could cause financial loss.

🎯 Goal: You will create a small program that stores transactions, sets a minimum security threshold, filters out invalid transactions, and then shows only the safe transactions. This teaches how security checks help prevent financial loss.

📋 What You'll Learn

Create a dictionary called transactions with exact entries for senders, receivers, and amounts

Create a variable called min_amount to set the minimum allowed transaction amount

Use a dictionary comprehension to create a new dictionary secure_transactions that only includes transactions with amounts greater than or equal to min_amount

Print the secure_transactions dictionary to show the filtered safe transactions

💡 Why This Matters

🌍 Real World

In real blockchain systems, security checks prevent fraudulent or invalid transactions that could cause financial loss.

💼 Career

Understanding how to filter and validate data is essential for blockchain developers and security engineers to protect assets.

1

DATA SETUP: Create the transactions dictionary

Create a dictionary called transactions with these exact entries: "tx1": {"sender": "Alice", "receiver": "Bob", "amount": 50}, "tx2": {"sender": "Charlie", "receiver": "Dave", "amount": 20}, "tx3": {"sender": "Eve", "receiver": "Frank", "amount": 5}

Blockchain / Solidity

# Create the transactions dictionary with exact entries
# Your code here

Need a hint?

Use curly braces to create the dictionary. Each key is a string like "tx1" and each value is another dictionary with keys "sender", "receiver", and "amount".

2

CONFIGURATION: Set the minimum allowed transaction amount

Create a variable called min_amount and set it to 10 to represent the minimum secure transaction amount

Blockchain / Solidity

transactions = {
    "tx1": {"sender": "Alice", "receiver": "Bob", "amount": 50},
    "tx2": {"sender": "Charlie", "receiver": "Dave", "amount": 20},
    "tx3": {"sender": "Eve", "receiver": "Frank", "amount": 5}
}
# Set the minimum allowed transaction amount
# Your code here

Need a hint?

Just create a variable named min_amount and assign the number 10 to it.

3

CORE LOGIC: Filter transactions using dictionary comprehension

Use a dictionary comprehension to create a new dictionary called secure_transactions that includes only those transactions from transactions where the amount is greater than or equal to min_amount

Blockchain / Solidity

transactions = {
    "tx1": {"sender": "Alice", "receiver": "Bob", "amount": 50},
    "tx2": {"sender": "Charlie", "receiver": "Dave", "amount": 20},
    "tx3": {"sender": "Eve", "receiver": "Frank", "amount": 5}
}

min_amount = 10
# Use dictionary comprehension to filter transactions
# Your code here

Need a hint?

Use {key: value for key, value in transactions.items() if value["amount"] >= min_amount} to filter.

4

OUTPUT: Print the secure transactions

Write a print statement to display the secure_transactions dictionary

Blockchain / Solidity

transactions = {
    "tx1": {"sender": "Alice", "receiver": "Bob", "amount": 50},
    "tx2": {"sender": "Charlie", "receiver": "Dave", "amount": 20},
    "tx3": {"sender": "Eve", "receiver": "Frank", "amount": 5}
}

min_amount = 10

secure_transactions = {tx_id: details for tx_id, details in transactions.items() if details["amount"] >= min_amount}
# Print the secure_transactions dictionary
# Your code here

Need a hint?

Use print(secure_transactions) to show the filtered transactions.