Altcoins

Question 1

3 changes in altcoins

Answer 1

1. block generation time
2. hash function used
3. total coin supply

Question 2

Namecoin

Answer 2

• namecoin is new domain-name system to register web addresses
• participants of namecoin control domain names

Question 3

Litecoin

Answer 3

Generate block every 2.5 minutes => faster confirmation
sha256 => scrypt to decrease importance of customized hardware
litecoin network produces four times as many coins as btc

Question 4

Dogecoin

Answer 4

generate block every minute => higher orphaned rate, faster verification
scrypt, 100 billion dogecoins, different rewards

Question 5

Required confirmations

Answer 5

Dogecoin, litecoin, ethereum require many more confirmations to match 6 confirmations of bitcoin

Question 6

Proof of X

Answer 6

Nakamote-style Proof of X
Select leader randomy to generate next block
random select resilient to sybil attack as well as censorship

Question 7

PoS Issues

Answer 7

Nothing at stake:
Deliberate forking with no cost => Work on multiple forks to increase winning ods
=> a lot of active forks in network => deposit based PoS to punish working on multiple forks
History attack:
Blocks are never finalized => enough adventage in the past can overtake main fork
=> checkpoint at somepoint to limit range of attack
Grinding attack: Combining computational resources have advantages in leader selection. Deterministic leader eligibility check can be predictable

Question 8

TEE based PoS

Answer 8

blocks are signed by a trusted application protected by TEE
=> can only sign correct blocks
=> monotonic counter tracks block height of last signing request

Question 9

Proof of elapsed time

Answer 9

Wait for x time to create block => no unfair advantage by computing power