Introduction to Blockchain technology

An explanation of blockchain technology for understanding the quantum threat better.

Definition of Blockchain

A blockchain is “a distributed database that maintains a continuously growing list of ordered records, called blocks.” These blocks “are linked using cryptography. Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data. A blockchain is a decentralized, distributed and public digital ledger that is used to record transactions across many computers so that the record cannot be altered retroactively without the alteration of all subsequent blocks and the consensus of the network1.

Blockchain checklist

A blockchain by definition should have the following essential properties:

  • Decentralisation - ensures that the blockchain is not governed by an individual, group, or even the government
  • Immutability - ensures that no one can tamper with the system or change the data that has already been saved into the block
  • Consensus mechanism - maintains the security of the blockchain by keeping a record of all legitimate transactions
  • Transparent ledger - for providing a high level of trust and integrity
  • Cryptography - primary for ensuring the security of participants, transactions, and safeguards against double-spending

In the next section, we will dive into where cryptography is being used within the blockchain.

Cryptography in the Blockchain

Cryptography is being used in various places in the blockchain technology. First and foremost, it is being used in cryptocurrency addresses. Cryptocurrency addresses, where the user can share their hashed public key in an encoded form to the cryptocurrency’s own wallet format and keep the private key to themselves - where the private key can be used to sign transactions to prove ownership of the public key. This ensures the security of all participants - protected funds and where transactions can take place without any centralised governance together with the above properties.

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