History of Bitcoin blocksize debate. Video of the presentation https://www.youtube.com/watch?v=Rnvo4muAXB4&feature=youtu.be&t=1h7m20s

1. BITCOIN FORK WARS
From XT to 2X
By Federico Tenga
COO at Chainside
Sticker producer

2. THE PROBLEM
Due to its structure, Bitcoin is extremely limited in supporting
a large number of transactions on-chain

3. BLOCKSIZE LIMIT
Originally the blocksize limit was set to 32MB, but then Satoshi
lowered it down to 1MB

5. Was is supposed to be temporary?

9. Season 2: Bitcoin Classic

10. BLOCK SIZE INCREASE
Pros
More on-chain txs
Cheaper fees
Cons
More block rely latency
More expensive to run a node
Not a long term solution

11. FORK WARS
Season 1: Bitcoin XT

13. BITCOIN XT
Fork of Bitcoin Core, first release December 27, 2014
Initially intended to support Lighthouse crowdfunding platform
Lead dev Mike Hearn

14. THE HARD FORK
June 22, 2015: Gavin Andresen proposes an increase for max block size
August 6, 2015 Andresen's proposal was merged into the XT codebase
August 15, 2015 version 0.11A was released to the public

15. THE HARD FORK
The forks activates after 75% of the blocks mined after the beginning of 2016
signal support
The block size will initially increase to 8MB and will double every two years
In 2036 the blocksize limit will be 8GB

17. MEANWHILE: SEGWIT WAS BORN

18. THE PROBLEM
Signatures of Bitcoin transaction can be slightly altered without invalidating the
signatures (malleability bug)
This means that the txID can be altered
Malleated transactions are still valid, but transaction spending the malleated one are not
Hard to build second layer solutions and bi-directional payment channels

19. 2015 malleability attack on Bitcoin

20. THE IDEA
Separate the signature data in a new field which is not considered to calculate
the txID
BTW it is also a blocksize increse
But you kinda need a hard fork for that
Maybe…

23. FORK WARS
Season 2: Bitcoin Classic

24. BITCOIN CLASSIC: THE FIRST COMPROMISE
Let’s increase the size limit to 2 MB
Let’s buy some time
Hard fork still required

26. HONG KONG AGREEMENT
SegWit is expected to be released in April 2016
The code for the hard-fork will therefore be available by July 2016
If there is strong community support, the hard-fork activation will
likely happen around July 2017

27. FORK WARS
Season 3: SegWit vs Unlimited

28. SEGWIT RELEASE
Merged into Core 0.13.1 in October 2016
Implemented also by Bitcoin Knots and Bcoin
Requires 95% hashing power to activate
Miners signalling starts on November 15th
Expected to be activated quickly

30. THE OPPONENT: BITCOIN UNLIMETED
Users can set the max blocksize they accept and produce
You accept some invalid blocks if there is enough work
Absolute max block size 32MB

31. January 4th, 2017

32. February 4th, 2017

33. May 15th, 2017

34. FORK WARS
Season 4: UASF and the NYA

35. WHAT IS UASF
Proposed by the anonymous developer ShaolinFry
Instead of using HP, users set a flag day where nodes start to
enforce the new rules
Economic majority set the rules

36. BIP 148
On August 1st 2017 nodes start refusing blocks that don’t
signal SegWit
Good community support
No major exchange declare support

37. MEANWHILE…

40. THE NEW YORK AGREEMENT
After 2017 Consensus conference, DGC Barry Silber
organizes a meeting between Bitcoin companies’ CEO and
miners
They agree to activate the segwit2x upgrade, proposed by
RSK founder Sergio Demian Lerner
Requires a hard fork

42. Believed to be a great compromise that will make
everybody happy

43. Not everybody is happy…

45. Meanwhile…

46. BITCOIN CASH IS BORN!!
a.k.a.
Bcash
BCH
BCC

47. WHAT THE IS BITCOIN CASH ANYWAY?
8MB blocks
No SegWit
Emergency difficulty adjustment
Actually has some community support

48. BIP91
Developed by James Hilliard, BIP91 manages to keep UASF
and NYA nodes on the same chain

51. Everybody happy?

52. FORK WARS
Season 5: NO2X

53. PROBLEMS WITH SEGWIT2X
SegWit is already a blocksize increase, we don’t really
need a 2x at the moment
Not enough time for nodes to upgrade
High risk of chain split , not really worth it
Mostly political

59. BITCOIN FORK WARS
Federico Tenga
federico@chainside.net
@FedericoTenga