Seems we're going with block 7.28M for the #Ethereum Constantinople refork scheduled for the 27th of February! Will be a single fork on mainnet and a post-Constantinople-fixup fork on the testnets to get them back in line feature wise with the main network.— Péter Szilágyi (@peter_szilagyi) January 18, 2019
Security Issues With Ethereum Improvement Proposal (EIP) 1283
Constantinople, which is a hard fork update to Ethereum’s blockchain, was initially scheduled for January 16, however it was rolled back due to security issues in ethereum improvement proposal (EIP) 1283.
Szilágyi, who earned his Phd in computer systems networking from Romania’s Babes-Bolyai University, explained the Constantinople “refork” has now been scheduled for February 27, 2019. This, after blockchain security firm ChainSecurity revealed it found a critical vulnerability in Ethereum’s codebase modifications that were to be activated with the Constantinople update.
According to ChainSecurity, the software bug could have left some smart contracts vulnerable to attacks. The vulnerability could have also led to a loss of funds. Soon after, ChainSecurity sent out an alert regarding the bug, and Ethereum’s development team decided to delay the Constantinople upgrade.
Explaining how the Ethereum hard fork will be initiated next month, Szilágyi said there “will be a single fork on mainnet and a post-Constantinople-fixup fork on the testnets to get them back in line feature wise with the main network.”
Ethereum's Difficulty Bomb
As CryptoGlobe reported, a significant number of full-node operators had already activated Constantinople. However, they had to revert to the previous version of Ethereum’s codebase to avoid being forked out of consensus. Ethereum network’s block number 7,080,000, which was the point when Constantinople was expected to go live, has now passed without any issues.
There are, however, other technical challenges that Ethereum’s network must handle, including the so-called “difficulty bomb”. In October 2017, the difficulty bomb was postponed until 3 million additional blocks were mined. This delay was programmed when Ethereum’s Byzantium hard fork was activated at block height 4,370,000. Almost three million additional blocks have now been mined since Byzantium, and the difficulty bomb appears to be in effect.
It appears the Ethereum difficulty bomb has already activated. I had read EIP-649 to mean it would push 3mn blocks from 4,370,000 but in fact it gets to the same state as that block, at 7,370,000.— Eric Conner (@econoar) January 16, 2019
So, this means we are currently creeping on slower and slower block times.
As a result of the difficulty bomb, average block times on Ethereum appear to be increasing.
Transitioning To Proof-of-Stake (PoS)
Ethereum’s developers have designed the difficulty bomb in order to exponentially increase mining difficulty. This will effectively make mining ETH impossible and this is when the Ethereum blockchain is expected to transition to a proof-of-stake (PoS) consensus mechanism.
According to calculations performed by blockchain developer, Níckolas Goline the Ethereum network could see block times of around 60 seconds on February 27, which is also when Constantinople is scheduled to be activated. These estimates are based on the Ethereum network’s current mining difficulty level and hashrate trends. Should block times become this slow, then Ethereum-based decentralized applications (dApps) may be negatively affected.
According to available data, Ethereum’s hashrate has decreased by roughly 44% last year, from its peak in August 2017.