Blockchain is a distributed ledger system that records transactions in blocks of data that are linked together via cryptography. Each participant maintains a copy of the ledger with all transactions. New transactions are distributed across the network, validated by consensus, and added to each participant's ledger in a new block. The use of cryptography makes the records immutable and resistant to hacking or modification (paragraph 1). Blockchains are composed of blocks of transactions, a chain that links blocks, and a peer-to-peer network of nodes that maintain the complete record (paragraph 2). Blockchain allows peers to transact without a central authority by reaching consensus on transactions and maintaining an identical record of the ledger through cryptography (paragraph 3).

1. BLOCKCHAIN
BY CA CHELLADURAI B FCA

2. WHAT IS
BLOCKCHAIN?
• Blockchain is a system of recording information in a way that makes it
difficult or impossible to change, hack, or cheat the system.
• A blockchain is essentially a digital ledger of transactions that is duplicated
and distributed across the entire network of computer systems on the
blockchain. Each block in the chain contains a number of transactions, and
every time a new transaction occurs on the blockchain, a record of that
transaction is added to every participant’s ledger. The decentralised
database managed by multiple participants is known as Distributed Ledger
Technology (DLT).
• Blockchain is a type of DLT in which transactions are recorded with an
immutable cryptographic signature called a hash.

3. Structure of Blockchain
Blockchains are now recognized as the "fifth evolution" of computing,
the Internet. Blockchains can create trust in digital data. When
a blockchain database, it's nearly impossible to remove or change it.
existed before.
Blockchains are composed of three core parts:
• Block: A list of transactions recorded into a ledger over a given
period. The size, period, and triggering event for blocks is different
Not all blockchains are recording and securing a record of the
cryptocurrency as their primary objective. But all blockchain do record
cryptocurrency or token. Think of the transaction as simply being the
Assigning a value to it (such as happens in a financial transaction) is
data means.

4. • Chain: A hash that links one block to another, mathematically
"chaining" them together. This is one of the most difficult concepts
comprehend. It's also the magic that glues blockchains together and
mathematical trust.
The hash in blockchain is created from the data that was in the
fingerprint of this data and locks blocks in order and time.
• Network: The network is composed of "full nodes." Think of them as
the computer running an algorithm that is securing the network.
complete record of all the transactions that were ever recorded in
• The nodes are located all over the world and can be operated by
expensive, and time-consuming to operate a full node, so people
incentivized to operate a node because they want to earn
blockchain algorithm rewards them for their service. The reward is
cryptocurrency, like Bitcoin.

5. Basic Operations of Blockchain
• Blockchain is a peer-to-peer ledger system that allows peers to transact between them
without any centralized authority. The peer-to-peer network is completely decentralized. To
make it decentralized, each peer carries a copy of the ledger. The ledger can be a complete
copy or a minimal copy required for it to stay connected and functional to the network.
• To ensure consensus across transactions, consensus methods like proof of work, Proof-
of-Stake, or others are used. Also, each transaction is completely secured with the help of
advanced cryptographic algorithms. Clearly, the whole blockchain mechanism is used to
taking advantage of trust, immutability, and transparency. The idea is the complete opposite
of centralization.
• In short, it is a network with peers capable of doing transactions without any centralized
authority. This simple idea is single-handing changing how industries work. This is
how blockchain record transaction in the ledger.

6. Verification of integrity of records
In a blockchain, the stored data is the most important
attribute to protect against malicious manipulation and
corruption. If data integrity was compromised, the entire
chain would be invalidated and become untrustworthy. This
article will show how data integrity is achieved in a blockchain
by using hashes.
To highlight a real world implementation of data integrity on a
blockchain, Bitcoin is used as a comparison because of its
historical secure nature. Our own additional research
blockchain is also presented to highlight the differences
between hashing algorithm sizes.

7. Data integrity is achieved with the use of hashing data in the
blockchain. By using hashes, the blockchain can be verified to
not have been tampered with or altered. Bitcoin and our
blockchain use two similar but different methods of hashing
data. The process of hashing refers to “any function that takes
input of some length and compresses them into short, fixed
length outputs” (Katz & Lindell, 2008).
Each block in the blockchain computes a hash value into what
is called a digest. The digest relays proof to the user that the
data in the block is secure and the integrity remains valid. If
unauthorized modification to the block occurred, the digest
value would change producing an error on the blockchain.

8. Privacy and transparency in blockchains
Privacy
Within digital assets, anonymity is an essential feature for data
protection and data ownership. In a public blockchain, privacy is
secured by public addresses: a person is only linked to a public
address that does not reveal personal information such as actual
name or address. The public addresses act as pseudonymous
identities, for that matter, it is commonly said that a public
blockchain is not completely anonymous but rather
pseudonymous.

9. TRANSPARENC
Y
The way a public blockchain functions is transparent as every
node on the network stores a copy of the transactions and
verifies that no rules are being broken. Anyone can see live and
historical transactions and can search through blocks,
transactions and addresses. Each node has its own copy of the
chain that gets updated as fresh blocks are confirmed and
added. This means that it is possible to track a coin wherever it
goes. Therefore, if an exchange was to be hacked, the crypto
extracted would be easily traceable, even if the hacker remains
entirely anonymous.