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Huaqun Xingjie - A Survey on blockchain Technology and its Security - 2022 March

Public key cryptography

parties to enable secure and trusted records and transactions to
occur. Without Blockchain to create trusted records and
transactions, a third-party intermediary is necessary.
Blockchain uses cryptography and collaboration to create that
trust and as a result it eliminates the need for a centralized
institution to act as intermediary. Information on the
Blockchain is stored on the ledger using cryptography.
Blockchain makes use of some cryptography building
blocks as below [40]:
• Public Key Cryptography: Be used for digital
signatures and encryption.
• Zero-Knowledge Proof: Demonstrate the knowledge
of a secret without revealing it.
• Hash
Functions:
One-way
pseudo-random
mathematical functions. Merkle trees adopted hash
function to form one component of block header.
Public key cryptography. It is used to prove that a
transaction was created by the right person. In Blockchain, the
private key is kept in a digital wallet, either a hardware wallet
(a physical device to store the private key) or any software
wallet (e.g., desktop wallet app, mobile wallet app or web-
wallet). A user accesses its private key to sign a message
called as digital signature that will be transmitted to the
Blockchain, and its public key is to confirm that message
actually did come from the user. For example, in Fig. 2, the
user hashes its transaction data into hash value 1 and then
signs on the hash value 1 with its private key to generate the
digital signature. The user then sends its digital signature
together with its transaction data to the Blockchain network.
The miner uses the user’s public key to decrypt the received
digital signature to obtain hash value A, and the miner also
hashes the received transaction data to obtain another hash
value B. Then the miner checks if hash value A equals to hash
value B or not. If they are equal, the miner verifies the user’s
transaction.
Since the private key is only securely kept by its owner,
the corresponding digital signature makes sure the authorship
of the transaction. The algorithm enables that the digital
signature on every transaction depending on the individual
private key of each user. The pair of public key and private
key fits into Blockchain as a backbone of Blockchain and they
are used to sign and verify transactions that the user makes.
Fig. 2. Digital Signature and Hash used in Blockchain Transactions
Tx
xxx
Hash
Encrypt
User’s
Private Key
Tx
xxx
Tx
xxx
Decrypt
User’s
Public Key
= ?
A3hefg
A3hefg
A3hefg
Hash
User
Miner
Digital Signature
Verification
Journal Pre-proof

Both Ethereum and Hyperledger Fabric use digital
signatures on transactions and blocks to confirm the identity
of the creator and that the signed data has not been modified
since signing. Elliptic Curve Digital Signature Algorithm
(ECDSA) is widely adopted to create a pair of public key and
private key.
The public key of a user can be logically selected as an
identity of the user since knowledge of a public key is
necessary for verification of digital signatures. It is used in the
Blockchain as a method for managing users’ identities without
revealing real world identities.
T
ABLE
I.
C
OMPARISON OF
C
ONSENSUS
A
LGORITHMS
[41]
[42]
[13]
[43]
[44]
[45]

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