The Blackcoin Developers have announced that their coin is adopting what they are calling proof-of-stake protocol v2 in response to concerns from critics that say Proof-of-stake coins aren't secure.
Blackcoin is one of the most exciting altcoins in the cryptospace right now. It has a 30 second confirmation time, large market cap, their BlackHalo project is keeping it in the forefront of the Bitcoin 2.0 space and they seem to be the only team to get altmining pools done in a responsible way that doesn't harm other coins.
It is also proof-of-stake based, with its proof-of-work mining period long over. While, as the team and the white paper is quick to point out, proof-of-stake has been secure enough to prevent any serious security breaches to its 15 – 20 million dollar market (not to mention the markets of other proof-of-stake coins like NXTCoin, Peercoin and Novacoin) there have been some concerns voiced by the community.
Rather than waiting to see if their coin can withstand a serious attack when potentially hundreds of millions of dollars are on the line (assuming Blackcoin continues to grow) the developers are taking a proactive approach and plugging up those potential vulnerabilities now.
Proof-of-stake protocol v2 ditches the somewhat controversial Coinage system completely. Coinage is a system that has only coins, which have been moved into a wallet recently (after thirty days but less than ninety days), accruing interest in the minting process. This system was designed to encourage transactions and therefore spending. However, it resulted in a less secure system as nodes were able to gain enough influence over the system to perform a double spend. There was also an issue where honest nodes would only remain on while their coins were gaining interest. More nodes equates to a more secure network, so the new system is designed to encourage nodes to participate at all times by not deactivating minting on coins.
Adjustments have also been made to stop pre-computations of proof-of-stake. Proof-of-stake pre-computations had attackers matching or exceeding the network hashrates for short amount of times and rewriting the blockchain to double spend coins they do not yet have. Blackcoin's new system addresses this by changing the stake modifier at every modifier interval.
Blackcoin will also be switching from Scrypt to SHA256d because Scrypt doesn't offer any advantages in a proof-of-stake system and since Blackcoin's proof-of-work phase is over, it is no longer needed.
The team behind Blackcoin is dedicated, talented and apparently has a real knack for solving problems. Steve McKie, Project Manager for the Blackcoin Development team and representative of the Blackcoin Foundation stated:
“With PoS Protocol V2.0, we wanted to plug any searing vulnerabilities that may have existed in the protocols previous version that were left over from previous attempts at PoS (Peercoin, NovaCoin). The main developer of the protocol, Rat 4 (Pavel Vasin) has been hard at work making sure that BlackCoin users and merchants are as protected as possible from malicious attacks on the network”
In the same vein, Blackcoin is switching its Timestamp rules from ones that mirrored Bitcoin's to one that is designed to take advantage of the proof-of-stake system. You can see the differences below:
Bitcoin
Past limit: median time of last 11 blocks
Future limit: +2 hours
Granularity: 1 second
Expected block time: 10 minutes
Blackcoin (New rules)
Past limit: time of last block
Future limit: +15 seconds
Granularity: 16 seconds
Expected block time: 64 seconds
McKie and the team have big aspirations for Blackcoin and believe that the proof-of-stake system will prove to be more effective. “Proof-of-stake, we believe, will be the leading protocol going forward in regards to security and overall energy efficiency,” they said.