work.txt

# CS-4049-Blockchain-and-Cryptocurrency-Assignment-01-02
The project consists of two parts named as assignments in the following. The first assignment focuses on the blockchain features related to a single peer. The second assignment is related to network features.

**Assignment 1** [100 marks]
1. Create a New Block [10 marks]
A method to create a new block. To keep things simple, each transaction can be a simple string
of arbitrary length. Among other information, the block header will contain hash pointers to
the previous block and the root of the Merkel tree (see below). The nonce value will be initially
0. You can use any hash function of your choice including SHA256.
2. Create Merkel Tree [40 marks]
The blockchain implementation will provide the functionality to create Merkel Tree. All the
transactions of each block are arranged in a Merkel Tree.
3. Mine Block [20 marks]
A method to find the nonce value for the block. The target shall be adjustable as the number
of trailing zeros in the 256-bit output string.
4. Display Blocks [No separate marks]
A method to print all the blocks in a nice format showing block data such
as nonce, previous hash, and current block hash.
5. Display Merkel Tree [No separate marks]
Function to print all the transactions in a nice format showing the transactions and hashes.
6. Verify Block and Chain [20 marks]
Functionality to verify a block. Moreover, a functionality to verify the blockchain in case any
changes are made. The verification will consider the changes to the transactions stored in the
Merkel tree.

7. Change Block [No separate marks]
Function to change one or multiple transactions of the given block ref.
8. Calculate Hash [10 marks]
Function for calculating the hash of a transaction or a block. If the size of the transaction is very
large, then Merkle‐Damgard Transform shall be used.
Moreover, your assignment shall include the code to properly demonstrate the functionality of
the above features. No marks are awarded if a group is not able to show that the above-mentioned
features are working properly.

**Assignment 2** [200 marks]
Your blockchain should provide the following network-related features:
1. Create a P2P network [40 marks]
Nodes in the P2P network can be emulated using goroutines. Each node acts as a server and a
client. To provide server functionality, each node listens on a separate port.
2. Bootstrap node [20 marks]
One peer is designated as a bootstrap node. The IP address/port number of the bootstrap
node is globally known. The bootstrap node keeps track of the IP addresses/port numbers of
all other nodes in the P2P network. In other words, each node in the P2P network registers its
IP address/port number with the bootstrap node.
3. Joining the network [20 marks]
A new node is created and joins the network at any time. To join, the new node contacts the
bootstrap node to get the IP addresses/port numbers of a few existing nodes in the P2P network.
The received IP addresses/port numbers are used to establish connections with the neighbors.
4. Display P2P network [No separate marks]
A function to display all the nodes in the P2P network and how they are connected to each
other.
5. Transaction Propagation [40 marks]
Each node receiving a transaction can broadcast it using flooding. Alternatively, students
are allowed to implement the Gossip protocol. Each node keeps a list of recently received
transactions that are not yet included in any valid block. If the same transaction is received
twice, it is not added to the list.
6. Block mining and propagation [40 marks]
Once the list contains n transactions, a node creates a block and starts the mining process
(already developed in part 1). The mined block is broadcasted to the P2P network using
flooding.

7. Transaction list pruning [20 marks]
On receiving a mined block, a node verifies the block (already developed in part 1). If the block
is valid, the list of transactions locally maintained by the node is pruned to remove transactions
that are included in the mined block.
8. Block on longest chain [20 marks]
Each node strives to accept blocks on the current longest chain. If a node receives a block
belonging to the longer chain, it will accept the block and the previous block becomes orphan.
If some blocks are missing on the longest chain, the node asks a neighbor to receive the missed
blocks.
Moreover, your main shall include the code to properly demonstrate the functionality of the above
features. You must be able to demonstrate a P2P network with 10 nodes.