consensus and Forks

1. Consensus
Forks: Hard, Soft and ChainSplit
‫وانشقاق‬ ‫ها‬ ‫فورک‬ ،‫اجماع‬

2. If someone has 8 Bitcoins do they have 1
Bytecoin?

3. Bitcoin Constituents
• Network Protocol (TCP/IP)
• Core Cryptographic Functions
• Game Theoretical Equilibrium Systems (Dynamic)

5. Random but deterministic
input
sha256
output

7. 00000000009f766c17c736169f79cb0c65dd6e07244e9468bc60cde9538b551e

8. Let’s play a Game
Hello World ! nonce Vitalik Random Unicorn
Ethereum IbC miNing Satoshi Gwei
Monero x11 CKryptoAlgorithm Full node
Consensus Signature zKsnarks BIP66 SegWit
SmartContracts P/KEY BTCcore Cypher&unks
Julian@$$ange SegwitNOxs AdamBack Byzantium Oracles
Neo&Agent$mith HalFinney Decentralization
http://www.xorbin.com/tools/sha256-hash-calculator
Which word?
04f57e090dc3579ce7d9a5739152696ac014fcfeeeb40ff46581e4344aa4e8ec

11. • Check syntactic correctness
• Make sure neither in or out lists are empty
• Size in bytes <= MAX_BLOCK_SIZE
• Each output value, as well as the total, must be in legal money range
• Make sure none of the inputs have hash=0, n=-1
• Check that nLockTime <= INT_MAX, size in bytes >= 100, and sig opcount <= 2
• Reject "nonstandard" transactions: scriptSig doing anything other than pushing numbers on the stack, or scriptPubkey not matching the two usual forms
• …..
• https://en.bitcoin.it/wiki/Protocol_rules

12. consensus
Core devS
(reference client)
Wallet
devS/Users
Exchanges
Merchants
Miners
Full Node

13. To Fork or Not to Fork:
That is the Question !

14. ‫غیرمتمرکز‬ ‫افزار‬ ‫نرم‬ ‫یک‬ ‫در‬
•‫اجتناب‬ ‫شبکه‬ ‫مشکالت‬ ‫حل‬ ‫برای‬ ‫کد‬ ‫تغییر‬ ‫به‬ ‫نیاز‬
‫است‬ ‫ناپذیر‬.
•‫الزامیست‬ ‫کد‬ ‫تغییر‬ ‫برای‬ ‫اجماع‬ ‫به‬ ‫رسیدن‬
•‫میگذرد‬ ‫پذیری‬ ‫مقیاس‬ ‫مشکل‬ ‫حل‬ ‫از‬ ‫فراگیری‬ ‫مسیر‬
•‫دارید‬ ‫انرا‬ ‫نکردن‬ ‫قبول‬ ‫حق‬ ‫شما‬ ‫اما‬ ‫است‬ ‫قانون‬ ‫کد‬
•‫دارد‬ ‫را‬ ‫خود‬ ‫کوین‬ ‫بیت‬ ‫ساخت‬ ‫حق‬ ‫هرکس‬.

15. ‫پیدایش‬ ‫بلوک‬ Genesis Block
• Block size: 1 MB
• Algorithm type: Proof of Work (based on Sha256)
• Speed of a block mine: 10 minutes
• Difficulty time: every 2,096 blocks (~2 weeks)
• Number of transactions per second: 7 max (4.4 on average)
• *First Mined by Satushi

16. ‫تغییر‬ ‫روند‬
•‫ثبت‬BIP
•‫رسانی‬ ‫اطالع‬‫توسط‬ ‫همه‬ ‫به‬Bitcoin Core
•‫اجماع‬ ‫به‬ ‫رسیدن‬(‫نود‬ ‫فول‬–‫ماینر‬–‫مرچنت‬–‫یوزرها‬)
•‫کد‬ ‫سازی‬ ‫پیاده‬
•‫کد‬ ‫از‬ ‫استفاده‬ ‫و‬ ‫افزار‬ ‫نرم‬ ‫کردن‬ ‫اپدیت‬ ‫برای‬ ‫ها‬ ‫یوزر‬ ‫و‬ ‫ها‬ ‫ماینر‬ ‫تصمیم‬(‫قانون‬)‫جدید‬

17. ‫فورک‬ ‫هارد‬–‫فورک‬ ‫سافت‬

18. ‫هاردفورک‬
•‫نیس‬ ‫معتبر‬ ‫دیگر‬ ‫قبلی‬ ‫نسخه‬ ‫های‬ ‫تراکنش‬‫ت‬
•‫ناپذیر‬ ‫برگشت‬
‫فورک‬ ‫سافت‬
•‫معتبرند‬ ‫همچنان‬ ‫قبلی‬ ‫های‬ ‫تراکنش‬
•‫پذیر‬ ‫برگشت‬ ‫گاهی‬

20. Altcoins Based On Bitcoin Code
• Litecoin
• Dash
• Zcash

22. Bitcoin XT
• Dec 2014 , BIP 64
• 24 transactions per second
• 2MB block, then market driven block size up to 8 MB
• Bitcoin Classic
• very successful at first but Miners Dumped their Nodes.
• Still Alive

23. Bitcoin Classic
• February 2016.
• Hard fork of Bitcoin core
• 2MB block (later: set by users)
• Currently Active

24. Bitcoin Unlimited
• January 2016
• Miners decide on the size of their block.
• Blocks Up to 16 MB
• Did not set a Particular Fork Mechanism
• Not Active

25. Segregated Witness
• December 2015 . BIP141
• moves signatures From Blocks
• Soft fork
• Basic Layer for Lighting Network and Atomic Swaps

26. Bitcoin Cash
• NO to Segwit/2x
• Block size to 8MB
• Sudden Hardfork
• Creates opportunistic mining

27. Bitcoin Gold
• Hard fork
• New Mining Algorithm (Equihash)
• Mining difficulty estimated every block

28. Segwit2x
• Hardfork
• Implementation of Segregated Witness
• Raise the block size to 2MB
• No replay protection

29. Replay Protection
• Two Chains must be Double Spend Protected
• newly mined coins to be mixed into a transaction.
• Time-locks
• at least one side of the split could add a protocol rule

30. Other Famous Hard Forks

31. Forks as a means of Governance
• Ethereum and The Ethereum Foundation
• Bitcoin, Decentralization and Consensus

32. End
@Ziya_Sadr @HadiNem