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Section 3 - Wrap Up

Overview​

  • 3.12 Section 3 Quiz
  • 3.13 Summary

[3.12] Section 3 Quiz​

Question 1:

Hashing plays a key role in which of the following things for DLTs?

(Select all that apply)

  • Deciding how many transactions to include in a block
  • Linking a block to a previous block
  • Creating an address from a public key
  • Setting the block size limit
  • Deciding the transaction fees of a block

Question 2:

Which hash functions does Bitcoin?
  • RIPEMD160 and SHA256
  • Only RIPEMD160
  • Only SHA256
  • None of the previous

Question 3:

What is the purpose of the Merkle Root in the Bitcoin block header?
  • Links the block header to the current state of unspent transaction outputs
  • Links the block header to the previous block
  • Links the block header to the transactions contained within the block
  • Links the block header to its block creator (miner)

Question 4:

Bitcoin addresses are created by hashing the public key twice. Why is this?
  • To shorten the length of the public address, while providing extra safety
  • Only to shorten the length of the public address
  • Only for safety reasons
  • To create a large public address

Question 5:

Which of the following is true regarding DLT transaction signing algorithms?
  • Only signing algorithms approved by the National Institute of Standards and Technology (NIST) can be used.
  • The only signing algorithm available in DLT is the Elliptic Curve Digital Signature Algorithm (ECDSA) using the secp256k1 curve.
  • A single DLT must use only one signing algorithm with only one curve.
  • Different DLTs can use different and possibly multiple signing algorithms.

Question 6:

What happens if you sign two valid transactions (with the correct format, correct sequence number, enough gas to pay the fees, etc), where the first transaction is signed using ECDSA with curve secp256k1 and the second transaction is signed using EdDSA with curve ed25519, and you send both transactions to the Polkadot DLT network?
  • The network rejects both transactions
  • The network accepts both transactions
  • The network accepts the transaction signed with ed25519 but rejects the one signed with secp256k1
  • The network accepts the transaction signed with secp256k1 but rejects the one signed with ed25519

Question 7:

What can an MSP from organization A (org A) do in a Hyperledger Fabric network?

(Select all that apply)

  • Generate X.509 certificates for clients in org A
  • Generate X.509 certificates for peers and orderers from org A
  • Generate X.509 certificates for clients from org B
  • Revoke any emitted certificate on the network
  • Generate signatures
  • Validate signatures

Question 8:

Which of the following is true regarding creating, signing and sending transactions for permissionless DLT networks using the Overledger DLT gateway?

(Select all that apply)

  • You must create a DLT account for each DLT network you want to use.
  • Overledger knows user’s private keys.
  • You submit a transaction to Overledger using a standardised data model and receive back a transaction object to sign that uses the native data model.
  • Submitting a signed transaction to Overledger will broadcast the transaction to the DLT network.

Solutions:

  1. B. & C.
  2. A.
  3. C. (See 3.7)
  4. A.
  5. D. (See 3.8)
  6. B.
  7. A., B., E., & F. (See 3.9)
  8. A., C., & D.

[3.13] Summary​

Now that you have completed this course you will have gained both theoretical and practical knowledge about distributed ledger technologies, specifically:

Theoretical Summary

Reading and understanding the course articles will have provided you with the knowledge to understand the key foundational aspects of blockchains and other distributed ledger technologies. In summary you have learned:

  • What defines a ledger
  • What components make up distributed ledger technologies
  • What exactly is a blockchain
  • How distributed ledgers can be organised in an Unspent Transaction Output (UTXO) or Accounts based method
  • What cryptography underpins distributed ledger technologies

Practical Summary

Completing the course exercises will have provided you with the foundational practical experience to start creating multi-ledger decentralised applications (mDapps). In summary you have learned:

  • How to interact with multiple distributed ledger technologies (specifically Bitcoin, Ethereum and the XRP Ledger)
  • How to connect to multiple distributed ledger technology networks (specifically the test networks of the previously listed technologies)
  • How to read blocks, transactions and state information from these DLT networks
  • How to add new transactions to these DLT networks

Continuing with Overledger

Should you want to take your journey with Overledger to the next level, consider signing up for mainnet access via the Overledger Developer Portal. To do so, login and click on the “Request Access” button on the bottom left hand corner of the screen. Mainnet access is subject to licence fees, as discussed in the Developer Portal.

Next Learning Steps

There is still plenty to learn about distributed ledger technologies. We will consider this in the next discussion section.