What is Blockchain?

  • A Linked List
  • Replicated
  • Distributed
  • Consistency maintained by Consensus
  • Cryptographically linked
  • Cryptographically assured integrity of data
  •  Blockchain technology is a digital innovation that has the potential to significantly impact trusted computing activities and therefore cybersecurity concerns as a whole.
  •  Attractive properties of Blockchain
  •  Log of data with digital signature
  •  Immutable (once written – cryptographically hard to remove from
    the log)
  • Cryptographically secure – privacy-preserving
  • Provides a basis for trusted computing on top of which applications
    can be built


Uses Of Bitcoin:
  • Immutable Ledger of events, transactions, or time-stamped data
  • Tamper-resistant log
  • Platform to Create and Transact in Cryptocurrency
  • log of events/transactions unrelated to currency

Cryptography: Algorithms and Keys

• A method of encryption and decryption is called a cipher.
• Generally there are two related functions: one for encryption and
the other for decryption.
• Some cryptographic methods rely on the secrecy of the algorithms.
• Such methods are mostly of historical interest these days.
• All modern algorithms use a key to control encryption and
decryption.
• Encryption key may be different from the decryption key.



Trust Model:
• Cyber Security is all about who you trust?
• Trust your hardware to not leak your cryptographic keys?
• Trust your O/S to not peek into your computation memory?
• Trust your hypervisor to not mess up your process memory?
• Trust your application to not be controlled hijacked or attack by other applications?
• Where is your trust anchor?
• Hardware?
• Operating system?
• Application?
• Manufacturer?


The essence of bitcoin:

• A protocol that supports decentralized anonymous peer-to-peer
digital currency
• A publicly disclosed ledger of transactions
• A reward-driven system for achieving consensus (mining) based on
• "Longest chain for consensus”
• “Proofs of Work” for helping to secure the network
• A “scare token” economy with an eventual cap of about 21M bitcoins


Bitcoin and Ethereum Comparison:

Whereas Bitcoin is a cryptocurrency (with a basic scripting language), Ethereum is a full-fledged platform. Ethereum is a smart contract execution platform, and Bitcoin is a transaction execution platform. This means that Ethereum is a platform for building distributed applications: applications running on Ethereum as a platform. Bitcoin is a closed destination. It is designed to do one thing, execute one-time monetary transactions securely. Bitcoin is designed to be simple and robust, with high security and high fault tolerance. Complexity is not part of Bitcoin's design goal and therefore Bitcoin's smart contract language is simple and does not afford the same amount of complexity as Ethereum. As an application platform, Ethereum is designed to be complex and feature-rich. Another difference is that with Bitcoin, the Bitcoin asset is the center of the Blockchain's activity. In Ethereum, ether is an asset but not the primary goal of the system, but more of an economic mechanism aligning incentives for operating smart contracts.


Bitcoins and other cryptocurrencies:

• Too much interest by investors to park their assets
• Less used as a medium of value exchange
• Private Key stealing or private keys at exchanges — risk
• Coding vulnerabilities — risk
• Volatility
• Energy Waste — climate impact
• Too much concentration in one country — risk
• Regulatory risk
• Usage for criminal activities — Silk Road


Roles within Hyperledger Fabric Network:

  • Clients are applications that act on behalf of a person to propose transactions on the network.
  • Peers maintain the state of the network and a copy of the ledger. There are two different types of peers: endorsing and committing peers. However, there is an overlap between endorsing and committing peers, in that endorsing peers is a special kind of committing peers. All peers commit blocks to the distributed ledger.
  • - Endorsers simulate and endorse transactions
  • - Committers verify endorsements and validate transaction results, prior to committing transactions to the blockchain.
  • The ordering service accepts endorsed transactions, orders them into a block, and delivers the blocks to the committing peers.



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