Cyber Currency – part 3/5 – Blockchain


  • A digital ledger or journal of transactions (database)
  • Cryptographic in nature (encrypted)
  • A shared database with write permissions for everybody
  • Validity of transactions is determined cryptographically instead of by a central authority
  • Cryptographic nature
    • Each transaction is combined with the hash value from the previous transaction and a new hash value is calculated
    • Tamper proof because the data cannot be altered without changing the hash
  • Each block includes a hash from the previous block


  • Distributed
    • Copies of the blockchain are publicly available to anyone
    • Can be downloaded and updated over the internet
    • Can be browsed using a blockchain explorer:
      • – (bitcoin)
      • – (etherium)
      • – (litecoin)
      • – (multiple…)
  • Uses for blockchains:
    • Cyber currencies
    • Real estate transactions
    • Financial transactions of all kinds:
      • Bank statements
      • Accounting transactions
      • Cash receipts/sales
      • Expense accounts
    • Audit trails
    • Data changes, change log history (all kinds)
    • Licenses, certificates, titles, degrees
    • Medical records
    • Contracts
    • Voting systems
    • Insurance

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