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Blockchain CBBF Flashcards

1
Q

Who has a copy of the ledger in a blockchain?

A

Everyone has a local copy which can be queried and everyone should get the same answer

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2
Q

Is blockchain impervious to attack?

A

No, it is just a lot more difficult in a blockchain. A 51% consensus is required.

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3
Q

What is Byzantine Fault Tolerance?

A

Defend against failures of system components (with or without symptoms)
…that prevent other components of the system from reaching consensus.
…when consensus is needed for the correct operation of the system.

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4
Q

In the blockchain ……… has a copy of the ledger.

A

Everyone

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5
Q

New transactions are broadcast and …………… by the network.

A

Recorded

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6
Q

If everyone has a copy of the blockchain, when queries, everyone get the …………

A

Same answer

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7
Q

With a decentralised ledger no one has to ………. anyone else.

A

Trust

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8
Q

One of the advantages of a distributed network is many nodes or peers that are connected in a network create no single point of failure or ……….. control.

A

Centralised

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9
Q

The network is designed so that if some peers crash or attack the network maliciously, the network can still operate, this is known as …………..

A

Byzantine Fault Tolerance

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10
Q

What is the difference between a public and private blockchain?

A

Write permissions:

Public - everyone can write
Private - only certain participants can write

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11
Q

What is the difference between an Open vs a Closed blockchain?

A

Read permissions

Open - everyone can read from the blockchain
Closed - only certain participants can read

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12
Q

Who can see data on Ethereum blockchain?

A

Everyone can see everything at any time.

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13
Q

What is the pre-requisite for a permissioned blockchain system?

A

You must know the identity of the users

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14
Q

What kind of blockchain is Hyperledger (public or private)?

A

Private

It comes with native identity managment tools to manage permissions

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15
Q

Can you build a permissioned system on a non permissioned blockchain?

A

Yes. But as the developer, you will need to find a why to track identity and to add permissions based on that identity.

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16
Q

What type of blockchain is Ethereum?

A

Open
public
permissionless

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17
Q

What type of blockchain is Hyperledger?

A

Private
Closed
Permissioned

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18
Q

List some use cases for Hyperledger

A
  • Supply chains
  • Supplier/manufacturer inventory management
  • Managing internal business processes across geographically distributed locations
  • Allowing elected officials to vote on initiatives without being present
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19
Q

Describe a blockchain decision matrix

A

A graph with an axis for closed/open and another for private/public

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20
Q

What can Smart Contracts be used for?

A

Ability to automate processes

Blockchain as workflow (BPM)

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21
Q

Does Group consensus verify the truth of data itself?

A

No, it only verifies that the data was recorded correctly

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22
Q

Which are blockchain characteristics that are least appealing to most businesses?

A

Anonymity

Transparency

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23
Q

Is it ok to build your solution in multiple platforms?

A

Yes and it is often desirable.

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24
Q

Each block contains the hash of ……..

A

The previous block

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25
Only ........ of data can be made on or to the blockchain.
Additions
26
The blockchain provides a snapshot of the current state (true/false)
False, it has a record of all previous transactions.
27
When looking at public vs private Blockchains it is important to look at who can ......... data to the blockchain.
Write
28
Any blockchain solution must be either public or private (true/false)
False
29
When considering a permission-less blockchain it is important to ask: are all participants ........
Equal
30
Blocks are numbered in .............. order.
Ascending. | 0 is the first/oldest
31
Blocks are only linked to the previous because.....
They can’t be linked to the future one as this would require it to be changed. It can’t be changed once committed to the Ledger.
32
Blocks are created on a ..............
Schedule. Whether they are full or not they will be committed to the chain (providing they are validated) so that blocks are created at a set interval.
33
Block ....... is the hash of the data in the block
ID | digital fingerprint of that block
34
What data is captured in the header of a block? (7 items)
``` Version number of the block format Link to previous block Merkle root of transactions Creation Timestamp Mining difficulty Nonce All the transaction data ```
35
The number of a block is the ........ of the block.
Height
36
Blocks store .........
Digital data
37
The block ID is the. ............ of the data on the block, and the. ......... of that block.
Hash | Digital fingerprint
38
The connection between blocks means that the Blockchain is much more ........ than a standard database.
Tamper-proof
39
Cryptography can be used to address the issue of ..........
Privacy
40
What is a cryptographic function?
A way of encoding or encrypting data to protect the contents from adversaries.
41
Public key cryptography provides........... &............
Identity & Transaction approval
42
The public key .............
Verifies the digital signature of a given key pair
43
The private key .........
Signs/approves any transaction/action that might be made by the holder of the key pair.
44
In blockchain a ............key is used to validate that the transaction has come from the person it claims to have come from.
Public
45
What are the 4 terms used in cryptography
The secret The function The key The function
46
What is a cryptographic hash function?
- A hash is a one-was function, encrypted information CANNOT be decrypted. - Each unique input generates a unique output (deterministic)
47
Why would you want to use a cryptographic hash?
So that you can keep privacy. E.g. instead of using you name, you could use a hashed address as your account number which you could always prove is you. Passwords can be stored hashed too. Can use hashes to compare two documents, even if very long. Hash both copies, of both have the same hash, you know the documents are the same;
48
What technology can you use to check if two very large document contain exactly the same data?
Cryptographic Hash
49
Cryptography can be used to address the issue of ........
Privacy
50
............. is for encoding or encrypting data to protect the contents from adversaries.
A cryptographic function
51
Public key cryptography provides ................ and transaction approval.
Identity
52
........... verify the digital signature of a given key pair.
Public keys
53
................ sign/approved any transactions/action that might be made by the holder of a key pair.
Private keys.
54
Hashing is beneficial because it allows us to ..........
Instantly compare two or more large volumes of data to ensure they are the same.
55
Transactions take time to .........
Confirm
56
Each transaction, once it’s in an accepted block has a .........
Height
57
The height of a block is the number of blocks between it and the ...........block.
Genesis
58
Each increase in blockchain height is called a ...........
Confirmation
59
Data gets ......... secure as it the blocks after are added.
More
60
Best to wait for another 5 blocks after yours in confirmation for anything of value, a transaction 5 blocks below the top chain is said to have ...... confirmations.
6
61
When a transaction is submitted, .................... gets sent back straight away, but the actual confirmation (the transaction actually being added to the blockchain) can be minutes later.
acknowledgement
62
A fork occurs any time there is an update to the ........ or the ......... on a blockchain
Data | Protocol
63
If the upgrade is backward compatible, it is a ........... fork
Soft
64
If the upgrade is not backward compatible, it is a .......... fork
Hard
65
In a fork, blocks that are created have a ........... number.
Version
66
Hard forms are much harder and we try to ........... them.
Avoid
67
Upgrades to the protocol can cause problems, but can be managed. (true/false)
True
68
If the upgrade is backward compatible, it is a ........ fork.
Soft
69
All block data plus the current nonce are run through a .............
Cryptographic hash
70
If the result of a mining calculation matches the current level of ..........., the miner has guessed the right answer.
Difficulty
71
The miner with the answer. ........ it with other miners.
Shares
72
Miners share the answer with all other miners, miners will confirm the answer is correct by using the ......... with their ........... .............. to try and get the correct result.
Nonce | Block data
73
When ....... of the miners confirm the nonce is correct, the transaction is added to the blockchain.
51%
74
Which is the most commonly used consensus method?
Proof of work (POW)
75
When a block is full, or it is time to create a new block what happens? (6 steps)
1) All nodes stop accepting new incoming transactions 2) Any transactions that are broadcast to the network are cached on that node 3) Each node competes to guess the puzzle 4) The miner who guesses the nonce value shares the nonce with the rest of the network 5) They try this on their copy of their data, if 51% agree, the block is accepted. 6) The block is added to the chain
76
What are the limits of POW? (3)
- Limits transactions capacity - Uses a lot of electricity - Concern that it has become centralised as 80% of hash power come from less than a dozen datacenters mostly located in mainland China.
77
Do you need specialised equipment to participate in POS?
No
78
How does POS work?
- When a block is full of transactions. -All nodes have to take some funds and lock them into a stake. (Participation still is optional) - Protocol randomly selects a participant - The winner hashes and shares with rest of network. - Rest of network hashes their version and the two are compared. -All nodes vote to agree or disagree - If 51% agree, they get a reward. - If less than 51% agree, no reward and loose their stake.
79
Which is faster? POW or POS
POS
80
Name two other consensus methods. (5)
POA - Proof of activity POB - Proof of burn POC - Proof of capacity POET - Proof of elapsed time (based on custom chipset made by Intel) POA - Proof of authority
81
Consensus ........ are the key to Blockchain
Protocols
82
............is integral to understanding of the blockchain and working with it, but it not something that needs to be discussed with stakeholders when planning solutions.
Group consensuS
83
With proof of work, when a block is full, each node competes to guess the .......
Nonce
84
With proof of work, when ....... of the miners confirm the nonce is correct, the transaction is added to the blockchain.
51%
85
With proof of stake, no computing is ever performed only .........
Staking/wagering
86
Proof of stake is the most mature consensus method (true/false)
False. POW is.

Blockchain (8 decks)

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