2018 double-spend attacks on Equihash-based cryptocurrencies

From HandWiki

Between May and June, 2018, a number of cryptocurrencies based on Equihash algorithm and PoW consensus mechanism, Bitcoin Gold[1], ZenCash[2], Zcash and Litecoin Cash[3], suffered from 51% double spend attacks.

Affected Cryptocurrencies

Bitcoin Gold (BTG)

In May, 2018, unknown attackers successfully committed a double spend attack on Bitcoin Gold, a forked cryptocurrency from Bitcoin in 2017. An amount of approximately $18.6 million USD worth of Bitcoin Gold was stolen.[4][5][6][7]

On bitcoingold.org forum, the director of communications, Edward Iskra, wrote:

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ZenCash (ZEN)

ZenCash announced its network suffered a from 51% attack on June 2 and executed migrations to increase the difficulty for attack:

Follow Ups

Per zdnet.com reports[8], a website Crypto51[9] is setup to show the cost and difficulty to commit 51% double-spend attack for all PoW cryptocurrencies. In addition, a study by the University of Luxembourg found that up to 30% of the entire hashpower on Equihash-based coins were from high-efficiency ASIC miners, which could explain the unprecedented rise of successful attacks on algorithms once ASIC resistant.[10]

References

  1. "Double Spend Attack on Exchanges" (in en). https://forum.bitcoingold.org/t/double-spend-attack-on-exchanges/1362. 
  2. "ZenCash Statement on Double Spend Attack - ZenCash" (in en-US). ZenCash. 2018-06-03. https://blog.zencash.com/zencash-statement-on-double-spend-attack/. 
  3. "Blockchain's Once-Feared 51% Attack Is Now Becoming Regular - CoinDesk" (in en-US). CoinDesk. 2018-06-08. https://www.coindesk.com/blockchains-feared-51-attack-now-becoming-regular/. 
  4. "Bitcoin Gold loses millions as it is hit by a double spend attack" (in en-US). Fast Company. 2018-05-24. https://www.fastcompany.com/40577194/bitcoin-gold-loses-millions-as-its-hit-by-a-double-spend-attack. 
  5. Osborne, Charlie. "Bitcoin Gold suffers double spend attacks, $17.5 million lost | ZDNet" (in en). ZDNet. https://www.zdnet.com/article/bitcoin-gold-hit-with-double-spend-attacks-18-million-lost/. 
  6. "Responding to Attacks - Bitcoin Gold" (in en-US). Bitcoin Gold. 2018-05-24. https://bitcoingold.org/responding-to-attacks/. 
  7. "Bitcoin Gold Responds to Recent Double Spend Attack" (in en-US). CCN. 2018-05-25. https://www.ccn.com/bitcoin-gold-responds-to-recent-double-spend-attack/. 
  8. Osborne, Charlie. "Bitcoin Gold suffers double spend attacks, $17.5 million lost | ZDNet" (in en). ZDNet. https://www.zdnet.com/article/bitcoin-gold-hit-with-double-spend-attacks-18-million-lost/. 
  9. "Cost of a 51% Attack for Different Cryptocurrencies | Crypto51" (in en). https://www.crypto51.app/. 
  10. "University of Luxembourg: 30% of Equihash Hashrate is ASIC Miners, Enabling 51% Attacks - Chainstate" (in en-US). Chainstate. 2018-06-15. https://chainstate.org/2018/06/15/university-of-luxembourg-30-of-equihash-hashrate-is-asic-miners-enabling-attacks/.