Ethereum Classic

Ethereum Classic

Ethereum Classic
Original author(s)	Vitalik Buterin, Gavin Wood
Developer(s)	Open-source software development
Initial release	30 July 2015;8 years ago (2015-07-30)
Stable release	Spiral / 4 February 2024;12 days ago (2024-02-04)
Development status	Active
Software used	EVM 61 bytecode
Funding	Open Source Software
Written in	C++, Go, Python, Rust, Scala
Operating system	Cross-platform
Platform	x86-64, ARM
Size	Archive: 771GB / Snap Sync: 72GB (2023-Oct-03)
Available in	Global
Type	Open Source Software
License	Open-source licenses
As of	October 2023
Average performance	13.3 Seconds
Active users	45,281 Daily Transactions
Total users	100,256,926 Addresses
Total hosts	693 Nodes
Website	ethereumclassic.org

Ethereum Classic is a blockchain-based distributed computing platform that offers smart contract (scripting) functionality. ^[1] It is open source and supports a modified version of Nakamoto consensus via transaction-based state transitions executed on a public Ethereum Virtual Machine (EVM).

Ethereum Classic maintains the original, unaltered history of the Ethereum network. ^[2] The Ethereum project's mainnet was initially released via Frontier on 30 July 2015. However, due to a hack of a third-party project, The DAO, the Ethereum Foundation created a new version of the Ethereum mainnet on 20 July 2016 with an irregular state change implemented that erased the DAO theft from the Ethereum blockchain history. ^[2] The Ethereum Foundation applied their trademark to the new, altered version of the Ethereum blockchain. ^[2] The older, unaltered version of Ethereum was renamed and continued on as Ethereum Classic. ^[2]

Ethereum Classic's native Ether token is a cryptocurrency traded on digital currency exchanges under the currency code ETC. ^[3] Ether is created as a reward to network nodes for a process known as "mining", which validates computations performed on Ethereum Classic's EVM. Implemented on 11 December 2017, the current ETC monetary policy seeks the same goals as bitcoin: being mechanical, algorithmic, and capped. ETC can be exchanged for network transaction fees or other assets, commodities, currencies, products, and services.

Ethereum Classic provides a decentralized Turing-complete virtual machine, the Ethereum Virtual Machine (EVM), which can execute scripts using an international network of public nodes. The virtual machine's instruction set is Turing-complete, in contrast to others like Bitcoin Script. Gas, an internal transaction pricing mechanism, is used to mitigate spam and allocate resources on the network. ^[4]

Milestones

Frontier

Several codenamed prototypes of the Ethereum platform were developed by the Ethereum Foundation, as part of their proof-of-concept series, prior to the official launch of the Frontier network. Ethereum Classic followed this codebase after the DAO incident.

Date	Block	Milestone name
2015-07-30	0	Frontier
2015-07-30	1	5M20 Era 1
2015-09-08	200,000	Ice Age
2016-03-15	1,150,000	Homestead
2016-10-24	2,500,000	Gas Reprice
2017-01-13	3,000,000	Die Hard
2017-12-11	5,000,000	Gotham
2017-12-11	5,000,001	5M20 Era 2
2018-05-29	5,900,000	Defuse Difficulty Bomb
2019-09-12	8,772,000	Atlantis
2020-01-11	9,573,000	Agharta
2020-03-17	10,000,001	5M20 Era 3
2020-06-01	10,500,839	Phoenix
2020-11-28	11,700,000	Thanos
2021-07-23	13,189,133	Magneto
2022-02-12	14,525,000	Mystique
2022-04-25	15,000,001	5M20 Era 4
2024-02-04	19,250,000	Spiral
TBD	20,000,001	5M20 Era 5

The DAO bailout

Main article: The DAO (organization)

On 20 July 2016, as a result of the exploitation of a flaw in The DAO project's smart contract software, and subsequent theft of $50 million worth of Ether, ^[5] the Ethereum network split into two separate blockchains – the altered history was named Ethereum (ETH) and the unaltered history was named Ethereum Classic (ETC). ^[2]

• The new chain with the altered history was branded as Ethereum (code: ETH) with the BIP-44 Coin Index 60 and EVM Chain ID 1 attributed to it by the trademark-owning Ethereum Foundation. On this new chain, the history of the theft was erased from the Ethereum blockchain. ^[6]
• Some members of the Ethereum community ignored the change and continued to participate on the original Ethereum network. The non-fork chain with an unaltered history continued on as Ethereum Classic (code: ETC) with the BIP-44 Coin Index 61 and EVM Chain ID 61. ^[2]

Security vulnerabilities disclosed

On 28 May 2016, a paper was released detailing security vulnerabilities with the DAO that could allow Ether to be stolen. ^[7] On 9 June 2016, Peter Vessenes publicly disclosed the existence of a critical security vulnerability overlooked in many Solidity contracts, a recursive call bug. On 12 June 2016, Stephan Tual publicly claimed that the DAO funds were safe despite the newly-discovered critical security flaw.

Carbon vote

On 15 July 2016, a short notice on-chain vote was held on the DAO hard fork. ^[8] Of the 82,054,716 ETH in existence, only 4,542,416 voted, for a total voter turn out of 5.5% of the total supply on 16 July 2016; 3,964,516 ETH (87%) voted in favor, 1/4 of which came from a single address, and 577,899 ETH (13%) opposed the DAO fork. ^[8] The expedited process of the carbon vote drew criticism from opponents of the DAO fork. Proponents of the fork were quick to market the vote as an effective consensus mechanism, pushing forward with the DAO fork four days later. ^[9]

Block 1,920,000

The first Ethereum Classic block that was not included in the forked Ethereum chain was block number 1,920,000, which was generated by Ethereum Classic miners on 20 July 2016. ^{[8] [10]}

Defuse Difficulty Bomb

A mechanism called the "Difficulty Bomb" was designed to push the Ethereum chain from proof-of-work consensus mechanism to proof-of-stake in the future by exponentially increasing the difficulty of mining. This Difficulty Bomb was added to the network on block 200,000 in an upgrade named "Ice Age". While Ethereum Classic participants debated the merits of the Difficulty Bomb, a network upgrade called "Die Hard" at block 3,000,000 delayed the effects of the mechanism. Once the network participants came to consensus on the issue, Ethereum Classic upgraded its network on block 5,900,000 to permanently defuse the Difficulty Bomb. This abandoned a future with proof-of-stake and committed the network to the proof-of-work consensus mechanism.

Protocol parity

In an attempt to modernize the Ethereum Classic protocol, several protocol upgrades were scheduled to activate features that the Ethereum network already enabled over the past years. Atlantis, activated in September 2019, enabled the Agharta upgrade, which included the outstanding Byzantium changes. Agharta was followed by the incorporation of the Constantinople patches through the January 2020 upgrade. Finally, with the Phoenix upgrade, Ethereum Classic achieved protocol parity with Ethereum, allowing for fully cross-compatible applications between the two networks.

Mining algorithm

After a series of 51% attacks on the Ethereum Classic network in 2020, ^[11] a change to the underlying Ethash mining algorithm was considered by the community to prevent being a minority proof-of-work chain in the Ethash mining algorithm where Ethereum is dominating the hashrate. After evaluating various options such as Monero's RandomX or the standardized SHA-3-256, it was eventually decided to double the Ethash epoch duration from 30,000 to 60,000 in order to reduce the DAG size and prevent Ethash miners to easily switch to Ethereum Classic. This modified Ethash is also referred to as ETChash or Thanos upgrade.

Characteristics

Further information: Cryptocurrency

Ether (ETC)

ETC logo
Denominations
Plural	Ether(s)
Symbol	Ξ
Code	ETC
Nickname	Ether Classic, Eth Classic, Classic
Previous names	Ethereum, ETH, Eth
Precision	18
Subunits
10−9	Gwei
10−18	Wei
Development
Original author(s)	Vitalik Buterin, Gavin Wood
White paper	ethereum whitepaper
Implementation(s)	EVM 61
Initial release	Frontier / 30 July 2015;8 years ago (2015-07-30)
Latest release	Mystique / 12 February 2022;2 years ago (2022-02-12)
Code repository	github.com/ethereumclassic
Development status	Active
Written in	C++, Go, Python, Rust, Scala
Operating system	Cross-platform
Developer(s)	Open-source software development
Source model	Open-source model
License	Open-source licenses
Ledger
Ledger start	30 July 2015;8 years ago (2015-07-30)
Split height	#1,920,000 / 20 July 2016;7 years ago (2016-07-20)
Split from	Ethereum (ETH)
Split ratio	1:1
Timestamping scheme	Proof-of-Work - ETChash
Hash function	Keccak
Issuance schedule	Block reward reduction of 20% every 5,000,000 blocks
Block reward	ETC 2.56 + Uncle reqards
Block time	13.3 secs
Block explorer	Blockscout
Circulating supply	136,664,275 (2022-09-02)
Supply limit	210,700,000
Valuation
Exchange rate	1 ETC = $32.75 (2022-09-02)
Website
Website	ethereumclassic.org

As with other cryptocurrencies, the validity of each ether is provided by a blockchain, which is a continuously growing list of records, called "blocks", which are linked and secured using cryptography. ^{[12] [13]} By design, the blockchain is inherently resistant to modification of the data. It is an open, distributed ledger that records transactions between two parties efficiently and in a verifiable and permanent way. ^[14] Unlike Bitcoin, Ethereum Classic operates using accounts and balances in a manner called state transitions. This does not rely upon unspent transaction outputs (UTXOs). The state denotes the current balances of all accounts and extra data. The state is not stored on the blockchain, it is stored in a separate Merkle Patricia tree. A cryptocurrency wallet stores the public and private "keys" or "addresses" which can be used to receive or spend Ether. These can be generated through BIP 39 style mnemonics for a BIP 32 "HD wallet". In the Ethereum tech stack, this is unnecessary as it does not operate in a UTXO scheme. With the private key, it is possible to write in the blockchain, effectively making an ether transaction.

To send Ether to an account, the Keccak-256 hash of the public key of that account is needed. Ether accounts are pseudonymous in that they are not linked to individual persons, but rather to one or more specific addresses.

Ether

ETC is a fundamental token for operation of Ethereum Classic, which thereby provides a public distributed ledger for transactions. It is used to pay for Gas, a unit of computation used in transactions and other state transitions. Within the context of Ethereum Classic it might be called ether, but it should not be confused with ETH, which is also called ether.

It is listed under the currency code ETC and traded on cryptocurrency exchanges, and the Greek uppercase Xi character (Ξ) is generally used for its currency symbol. It is also used to pay for transaction fees and computational services on the Ethereum Classic network. ^[15]

Addresses

Ethereum Classic addresses are composed of the prefix "0x", a common identifier for hexadecimal, concatenated with the rightmost 20 bytes of the Keccak-256 hash (big endian) of the ECDSA public key (the curve used is the so-called secp256k1, the same as bitcoin). In hexadecimal, two digits represent a byte, meaning addresses contain 40 hexadecimal digits. An example of an Ethereum Classic address is 0xb794f5ea0ba39494ce839613fffba74279579268. Contract addresses are in the same format, however, they are determined by sender and creation transaction nonce. ^[16] User accounts are indistinguishable from contract accounts given only an address for each and no blockchain data. Any valid Keccak-256 hash put into the described format is valid, even if it does not correspond to an account with a private key or a contract. This is unlike bitcoin, which uses base58check to ensure that addresses are properly typed.

Monetary policy

On 11 December 2017, the total supply of Ether on Ethereum Classic was hard capped at ETC 210,700,000 via the Gotham hard fork upgrade. This added a bitcoin-inspired deflationary emission schedule that is documented in Ethereum Classic Improvement Proposal (ECIP) 1017. The emission schedule, also known as "5M20", reduces the block reward by 20% every 5,000,000 blocks. Socially, this block reward reduction event has taken the moniker of "the fifthening."

ETA Date	Date	5M20 era	Block	Block reward	Total era emission	Total emission
-	30 July 2015	Era 1	1	ETC 5	ETC 25,000,000	ETC 25,000,000
December 2017	11 December 2017	Era 2	5,000,001	ETC 4	ETC 20,000,000	ETC 45,000,000
March 2020	17 March 2020	Era 3	10,000,001	ETC 3.2	ETC 16,000,000	ETC 61,000,000
April 2022	25 April 2022	Era 4	15,000,001	ETC 2.56	ETC 12,800,000	ETC 73,000,000
May 2024	-	Era 5	20,000,001	ETC 2.048	ETC 10,240,000	ETC 83,240,000
~2027	-	Era 6	25,000,001	ETC 1.6384	ETC 8,192,000	ETC 91,480,000
~2029	-	Era 7	30,000,001	ETC 1.31072	ETC 6,553,600	ETC 98,033,000
~2031	-	Era 8	35,000,001	ETC 1.048576	ETC 5,242,880	ETC 103,275,880

Ethereum Classic Improvement Proposal

The Ethereum Classic Improvement Proposal (ECIP) process enables engineers and computer scientists to propose modifications, upgrades, or fixes. Any software developer who is a GitHub user is allowed to make contributions to the ECIP process. ^[17] There is a number of ECIP types, each listed in the table below. ^[18]

ECIP Types

Type	Explanation
Standard Track	Any change that affects most or all Ethereum Classic implementations
Core	Improvements requiring a consensus fork
Networking	Improvements to networking protocol specifications
Interface	improvements around client API/RPC specifications and standards and certain language-level standards
ECBP	Application-level standards and conventions, including contract standards
Meta	Proposes a change to, or an event in, a process and often requires community consensus
Informational	Discussing a design flaw in Ethereum Classic or offering general guidelines or information to the Ethereum Classic community, without suggesting the addition of a new feature

Code is law

The people who continued with Ethereum Classic advocate for blockchain immutability, and the concept that "code is law" ^[19] against the pro-fork side (Ethereum) which largely argued for extra-protocol intentionality, decentralized decision-making, and conflict resolution. ^[20] Code is law refers to the idea that the code is above all else including law from outside forces such as a government. The law is written into the code, therefore, anything the code allows is legal. ^[21]

Attacks

The DAO fork replay attacks

On 20 July 2016, due to reliance on the same clients, the DAO fork created a replay attack where a transaction was broadcast on both the ETC and ETH networks. On 13 January 2017, the Ethereum Classic network was updated to resolve transaction replay attacks. The networks are now officially operating separately. ^[8]

RHG sells stolen ETC

On 10 August 2016, the ETH proponent Robin Hood Group transferred 2.9 million stolen ETC to Poloniex in an attempt to sell ETC for ETH on the advice of Bitly SA; 14% was successfully converted to ETH and other currencies, 86% was frozen by Poloniex. ^[8] On 30 August 2016, Poloniex returned the ETC funds to the RHG. They set up a refund contract on the ETC network.

Classic Ether Wallet website attack

On 29 June 2017, the Ethereum Classic Twitter account made a public statement indicating reason to believe that the website for Classic Ether Wallet had been compromised. The Ethereum Classic Twitter account confirmed the details released via Threatpost. The Ethereum Classic team worked with Cloudflare to place a warning on the compromised domain warning users of the phishing attack. ^{[22] [ better source needed ]}

51% double spend attacks

ETC has experienced multiple 51% double-spending attacks throughout its history. These attacks exploit the decentralized nature of the network by amassing more than 50% of its mining power, ^[23] enabling attackers to manipulate transactions and double-spend digital assets. The first significant attack occurred in January 2019, when Ethereum Classic was subject to double-spending attacks and an estimated $1.1 million worth of ETC was double-spent. ^{[24] [25]} In response, the Ethereum Classic team initiated several network upgrades, including the adoption of a modified version of the Proof of Work (PoW) consensus algorithm called "ECIP-1049 Keccak256." ^[26] Despite these efforts, an additional 51% of attacks were carried out in August and October of 2020, ^{[27] [11]} with estimated losses of $5.6 million and $1.68 million, respectively. ^[28]

References

1. Vigna, Paul (28 October 2015). "BitBeat: Microsoft to Offer Ethereum-Based Services on Azure". The Wall Street Journal (Blog). News Corp. Retrieved 17 February 2016.
2. Vigna, Paul (1 August 2016). "The Great Digital-Currency Debate: 'New' Ethereum Vs. Ethereum 'Classic'". The Wall Street Journal (Blog). News Corp. Retrieved 5 March 2020.
3. Russel, Jon (11 June 2018). "Coinbase will add Ethereum Classic to its exchange 'in the coming months'". TechCrunch.com. TechCrunch. Retrieved 5 March 2020.
4. Tapscott, Don (2016). Blockchain revolution : how the technology behind bitcoin is changing money, business, and the world. Toronto, Ontario, Canada: Portfolio/Penguin. ISBN   978-0670069972.
5. Waters, Richard (18 June 2016). "'Ether' brought to earth by theft of $50m in cryptocurrency". Financial Times. Retrieved 19 October 2018.
6. Leising, Matthew (13 June 2017). "Ether thief remains mystery year after $55 million heist". www.bloomberg.com. Bloomberg News.
7. Popper, Nathaniel (27 May 2016). "Paper Points Up Flaws in Venture Fund Based on Virtual Money". The New York Times. ISSN   0362-4331 . Retrieved 12 July 2017.
8. Andreas M. Antonopoulos, Gavin Wood (2018): "Ethereum timeline". In Mastering Ethereum: Building Smart Contracts and DApps, page 329. O'Reilly Media; 424 pages. ISBN   9781491971918
9. De Jesus, Cecille (19 July 2016). "The DAO Heist Undone: 97% of ETH Holders Vote for the Hard Fork". Futurism, LLC. Archived from the original on 7 August 2017. Retrieved 16 May 2017.
10. Matthew Leising (2017-06-13): "The Ether Thief". Online article, Bloomberg. Accessed on 2019-02-16.
11. "Ethereum Classic faced '51 percent attack'" (in Turkish). Bloomberg HT. 31 August 2020.
12. "Blockchains: The great chain of being sure about things". The Economist . 31 October 2015. Retrieved 18 June 2016. The technology behind bitcoin lets people who do not know or trust each other build a dependable ledger. This has implications far beyond the crypto currency.
13. Narayanan, Arvind; Bonneau, Joseph; Felten, Edward; Miller, Andrew; Goldfeder, Steven (2016). Bitcoin and Cryptocurrency Technologies: a Comprehensive Introduction. Princeton: Princeton University Press. ISBN   978-0-691-17169-2.
14. Iansiti, Marco; Lakhani, Karim R. (January 2017). "The Truth About Blockchain". Harvard Business Review . Harvard University . Retrieved 17 January 2017. The technology at the heart of bitcoin and other virtual currencies, blockchain is an open, distributed ledger that can record transactions between two parties efficiently and in a verifiable and permanent way.
15. Popper, Nathaniel (27 March 2016). "Ethereum, a Virtual Currency, Enables Transactions That Rival Bitcoin's". The New York Times . Archived from the original on 24 July 2016. Retrieved 2 September 2016.
16. Wood, Gavin (3 February 2018). "ETHEREUM: A SECURE DECENTRALISED GENERALISED TRANSACTION LEDGER (EIP-150)". yellowpaper.io. Archived from the original on 3 February 2018. Retrieved 3 February 2018.
17. McIntyre, Donald (20 December 2022). "How to Contribute to ETC: The Improvement Proposal Process (ECIP)". ethereumclassic.org. Retrieved 20 December 2022.
18. "ECIPs". ethereumclassic.
19. Pearson, Jordan (27 July 2016). "The Ethereum Hard Fork Spawned a Shaky Rebellion". Motherboard. Retrieved 15 May 2017.
20. Primavera De Filippi (11 July 2016). "A $50M Hack Tests the Values of Communities Run by Code". Motherboard. Retrieved 15 May 2017.
21. Quinn, John. "'Code Is Law' During The Age Of Blockchain". Forbess. Retrieved 5 April 2023.
22. Russon, Mary-Ann (30 June 2017). "Classic Ether Wallet has been hacked – do not use it to send currency". International Business Times.
23. Frankenfield, Jake. "51% Attack: Definition, Who Is at Risk, Example, and Cost." Investopedia. Investopedia, 03 Jan. 2023. Web. 4 Apr. 2023.
24. Kharif, Olga (7 January 2019). "Ethereum Classic Movements Halted by Coinbase on Signs of Attack". Bloomberg.
25. Goodin, Dan (7 January 2019). "Almost $500,000 in Ethereum Classic coin stolen by forking its blockchain". Ars Technica.
26. Bob Summerwill, Alexander Tsankov. "Change the ETC Proof of Work Algorithm to KECCAK256." Ethereum Classic Improvement Proposals. 03 Nov. 2022. Web. 4 Apr. 2023.
27. Berbedj, Loana (17 August 2020). "Ethereum Classic cryptocurrency victim of two computer attacks in one week". Les Echos (in French).
28. Howarth, Dan. "Hackers Launch Third 51% Attack on Ethereum Classic This Month." Decrypt. Decrypt, 18 Nov. 2020. Web. 4 Apr. 2023.

External links

• EthereumClassic.org
• Ethereum Classic (ETC) Mining Calculator