Simulation of Blockchain Technology Gaming Project in C++

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#include <iostream>
#include <vector>
#include <string>
#include <sstream>
#include <iomanip>
#include <openssl/sha.h> // For SHA256 hashing

using namespace std;

// Function to calculate SHA256 hash of a string
string sha256(const string& input) {
    unsigned char hash[SHA256_DIGEST_LENGTH];
    SHA256_CTX sha256;
    SHA256_Init(&sha256);
    SHA256_Update(&sha256, input.c_str(), input.size());
    SHA256_Final(hash, &sha256);
    
    stringstream ss;
    for (int i = 0; i < SHA256_DIGEST_LENGTH; ++i) {
        ss << hex << setw(2) << setfill('0') << (int)hash[i];
    }
    return ss.str();
}

// Block class
class Block {
public:
    string previousHash;
    string hash;
    string data;
    long timestamp;

    Block(string data, string previousHash = "")
        : data(data), previousHash(previousHash), timestamp(time(nullptr)) {
        hash = calculateHash();
    }

    string calculateHash() const {
        stringstream ss;
        ss << timestamp << previousHash << data;
        return sha256(ss.str());
    }
};

// Blockchain class
class Blockchain {
private:
    vector<Block> chain;

public:
    Blockchain() {
        // Create the genesis block
        chain.push_back(Block("Genesis Block"));
    }

    void addBlock(const Block& newBlock) {
        chain.push_back(newBlock);
    }

    void printChain() const {
        for (const auto& block : chain) {
            cout << "Block Index: " << (&block - &chain[0]) << endl;
            cout << "Timestamp: " << block.timestamp << endl;
            cout << "Data: " << block.data << endl;
            cout << "Hash: " << block.hash << endl;
            cout << "Previous Hash: " << block.previousHash << endl;
            cout << "------------------------" << endl;
        }
    }
};

int main() {
    Blockchain blockchain;

    blockchain.addBlock(Block("Block 1 Data", blockchain.chain.back().hash));
    blockchain.addBlock(Block("Block 2 Data", blockchain.chain.back().hash));
    blockchain.addBlock(Block("Block 3 Data", blockchain.chain.back().hash));

    cout << "Blockchain contents:" << endl;
    blockchain.printChain();

    return 0;
}

#include <iostream>

#include <vector>

#include <string>

#include <sstream>

#include <iomanip>

#include <openssl/sha.h> // For SHA256 hashing

using namespace std;

// Function to calculate SHA256 hash of a string

string sha256(const string& input) {

unsigned char hash[SHA256_DIGEST_LENGTH];

SHA256_CTX sha256;

SHA256_Init(&sha256);

SHA256_Update(&sha256, input.c_str(), input.size());

SHA256_Final(hash, &sha256);

stringstream ss;

for (int i = 0; i < SHA256_DIGEST_LENGTH; ++i) {

ss << hex << setw(2) << setfill('0') << (int)hash[i];

}

return ss.str();

}

// Block class

class Block {

public:

string previousHash;

string hash;

string data;

long timestamp;

Block(string data, string previousHash = "")

: data(data), previousHash(previousHash), timestamp(time(nullptr)) {

hash = calculateHash();

}

string calculateHash() const {

stringstream ss;

ss << timestamp << previousHash << data;

return sha256(ss.str());

}

};

// Blockchain class

class Blockchain {

private:

vector<Block> chain;

public:

Blockchain() {

// Create the genesis block

chain.push_back(Block("Genesis Block"));

}

void addBlock(const Block& newBlock) {

chain.push_back(newBlock);

}

void printChain() const {

for (const auto& block : chain) {

cout << "Block Index: " << (&block - &chain[0]) << endl;

cout << "Timestamp: " << block.timestamp << endl;

cout << "Data: " << block.data << endl;

cout << "Hash: " << block.hash << endl;

cout << "Previous Hash: " << block.previousHash << endl;

cout << "------------------------" << endl;

}

};

int main() {

Blockchain blockchain;

blockchain.addBlock(Block("Block 1 Data", blockchain.chain.back().hash));

blockchain.addBlock(Block("Block 2 Data", blockchain.chain.back().hash));

blockchain.addBlock(Block("Block 3 Data", blockchain.chain.back().hash));

cout << "Blockchain contents:" << endl;

blockchain.printChain();

return 0;

}

Explanation

Headers:
- <iostream>: For input and output operations.
- <vector>: For using the std::vector container.
- <string>: For using the std::string class.
- <sstream>: For string stream operations.
- <iomanip>: For formatting output.
- <openssl/sha.h>: For SHA256 hashing. (You need OpenSSL library installed.)
Function sha256:
- Parameters:
  - const string& input: The input string to hash.
- Functionality:
  - Computes the SHA256 hash of the input string.
  - Returns the hash as a hexadecimal string.
Block Class:
- Attributes:
  - previousHash: The hash of the previous block.
  - hash: The hash of the current block.
  - data: The data stored in the block.
  - timestamp: The time when the block was created.
- Constructor:
  - Initializes the block with data and the hash of the previous block.
- Methods:
  - string calculateHash() const: Computes the hash of the block using SHA256.
Blockchain Class:
- Attributes:
  - chain: A vector of Block objects representing the blockchain.
- Methods:
  - Blockchain(): Creates the genesis block and initializes the blockchain.
  - void addBlock(const Block& newBlock): Adds a new block to the blockchain.
  - void printChain() const: Prints the details of each block in the blockchain.
Main Function:
- Initialization:
  - Creates a Blockchain object.
- Adding Blocks:
  - Adds several blocks to the blockchain with sample data.
- Display:
  - Prints the contents of the blockchain.

Notes:

Simple Blockchain: This example provides a basic implementation of a blockchain with hashing and linking of blocks. In real-world scenarios, blockchains involve more complex operations and security measures.

SHA256 Hashing: Uses the SHA256 algorithm for cryptographic hashing. You need the OpenSSL library installed to use the SHA256 functions.
Genesis Block: The first block in the blockchain is called the genesis block. It is hardcoded in this example.

Explanation

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