The ongoing block size dispute has catapulted to the center of attention again. One of the most talked-about developments is Segregated Witness, of which a public testnet iteration was launched last week. The innovation as recently proposed by Blockstream co-founder and Bitcoin Core developer Dr. Pieter Wuille is the centerpiece of a scalability “roadmap” set out by Bitcoin Core.

But relying on Segregated Witness as the next step of Bitcoin’s scalability process is opposed by the recently launched Bitcoin Core fork Bitcoin Classic. Rather than a Segregated Witness soft fork, Bitcoin Classic prefers to deploy a “cleaner” hard fork in order to increase the block size limit to 2 megabytes.

To find out where the development community stands on this issue, Bitcoin Magazine reached out to library and wallet developers – those who will need to do the heavy lifting in order to utilize Segregated Witness once rolled out.

In this, part 3 of a series: Breadwallet CEO Aaron Voisine.

The Other Side of Segregated Witness

Wuille’s Segregated Witness proposal is set to improve the Bitcoin network in several ways. For one, it effectively increases the block size to some 1.75 megabytes to 2 megabytes. But interestingly, many developers are more excited about the other improvements Segregated Witness has to offer.

This is true for Voisine as well.

“Segregated Witness is worth the effort even if it provided no block size increase,” Voisine said. “It has lots of advantages. The thing I think is most interesting about SegWit soft-fork technique is the ability to add new signature types such as Schnorr signatures. This means that if elliptic curve algorithms were broken, for instance by quantum computers in the future, we could fix that with only a soft fork, by adding a new quantum resistant digital signature algorithm. The fact that we get a quick, effective bump in block space is just a bonus.”

As such, Voisine plans to roll out support for Segregated Witness on the popular Bitcoin wallet app for iOS.

“The implementation is not especially difficult, and it’s opt-in for wallet developers,” Voisine explained. “Existing wallets that don’t upgrade will continue to work, they will just need to pay higher fees because their transactions will be larger than Segregated Witness transactions. With Breadwallet, we’ve started working on our implementation and should be ready to try it out on the Segregated Witness testnet over the next few weeks.”

Soft Forks vs. Hard Forks

The most notable difference between Bitcoin Core and Bitcoin Classic is that the former prefers a soft-fork increase in block size through Segregated Witness. A soft fork can be employed through miner-support only, and is therefore considered a safer solution by Bitcoin Core developers. The Bitcoin Classic team, however, believes these risks are overblown, and considers a hard fork more desirable.

Voisine said he sees merit in a soft fork as well – though he notably expressed support for Bitcoin Classic, too.

“I think we should do the Segregated Witness soft fork first,” Voisine said. “It will be quicker to achieve consensus. However, Segregated Witness will only give us something like an 80 percent capacity increase, and hard forks take a long time to deploy. The hard fork needs to be readied, and roll-out started quickly after. While I’d prefer it if Bitcoin Core does that, it appears Bitcoin Classic is the leading option for deploying a hard fork. As such, we do support that project.”

For more information on Segregated Witness, see Bitcoin Magazine’s three–part series on the subject, or part 1 and part 2 of this development series.