On 9th August, the Co-Founder of IOHK and the Creator of Cardano protocol, Charles Hoskinson shot a rebuttal on Twitter against Vitalik Buterin’s accusations at Ouroboros. In the month of July, Buterin had posted on the subreddit of Ethereum, a few points regarding Ouroboros versus Casper.
Team A: Ouroboros; used by Cardano
Team B: Casper; used by Ethereum
Both the algorithms are based on the Proof-of-Stake protocol.
In response to this, Hoskinson tweeted a post containing Cardano’s official rebuttal to Buterin. The blog is titled ‘How does Casper compare to Ouroboros?’. Here, Ouroboros has been defined as ‘a formally specified and analyzed protocol with mathematically proven security guarantees based on clearly specified assumptions’.
Rebuttal to Vitalik: https://t.co/hNhyCLU6Kv
— Charles Hoskinson (@IOHK_Charles) 9 August 2018
On the other hand, Cardano wrote that there are currently no published sources that provide a description of how Casper operates. Moreover, the blog claimed that Casper holds weaker guarantee than Ouroboros on how much stake is required to be controlled for the protocol to run smoothly. Countering this, Vitalik Buterin took to Twitter and replied on Hoskinson’s tweet, saying:
Cardano stated that “persistence and liveness” are the two fundamental properties required for the establishment of any PoS based consensus protocol. While persistence determines the immutability and finality of the ledger, liveness adds the verified transactions to that immutable ledger.
Under ‘Stake Assumptions’, Cardano wrote that Ouroboros possesses the fundamentals of persistence and liveness via assumptions of ‘honest majority of all stakes in the system’. On the other hand, in Casper, honest parties control only a small fraction of the deposited stake. Buterin’s counter to this, as stated by him is:
“This completely misses (i) *incentive* properties, (ii) network synchrony assumptions”
Cardano also mentioned, under ‘Network Assumptions’ that Casper has no defined network setting in which it operates and follows a similar approach in stating defense mechanisms against long-range attacks. In this matter, Buterin outrightly denied the mentioned points about Casper and commented:
“This is just a lie. Eg. page 4 of the Casper FFG paper: “Plausible liveness means that, regardless of any previous events (e.g., slashing events, ****delayed blocks****, censorship attacks, etc.)” “
Here are a few other thread-tweets posted by Buterin opposing Cardano’s rebuttal:
On Ethereum’s subreddit, Buterin also stated that a Reddit post where he attempted to understand Cardano has yet not been attended to. Although the Cardano team has written ‘hit’ article, it has not replied to all of the questions raised by Buterin. He counted this as a pedantry approach to the matter, rather than a sincere one to understand the Casper protocol.
The original Reddit post by Buterin can be viewed here: