Zclassic Development in Review

Crypto Prof. Utonium
5 min readMar 5, 2020


2019 was the year of attacks. Ethereum Classic, Vertcoin, Verge, Bitcoin Gold, etc. were 51% attacked and double-spent which raised a lot of questions about thesesystemic flaws or weaknesses of altcoins with low hash power.

Hence, last year, the main focus was on securing the blockchain from attacks and driving user adoption.

Zclassic in its development diverged from Zcash after implementing the Deep Reorg Protection inspired from Bitcoin Cash. You could say that Zclassic encompasses the best of both worlds, Zcash and Bitcoin Cash. The privacy features of Zcash with ASIC resistance and no tax. Faster transaction finality and Simple Ledger Protocol implementation from Bitcoin Cash.

Deep Reorg Protection

A Blockchain Reorganization occurs when miners collaborate to control more than 50% of the hash power and use it to remove previously confirmed blocks from the blockchain. This is known as a 51% attack. This attack can be used to double-spend by spending funds, erasing the transaction from the record, and spending the same funds a second time. All blockchains are vulnerable to a 51% attack as can be seen on this here, which shows the cost of performing a 51% attack on a network.

To defend against these hostile reorgs, Zclassic borrowed from Bitcoincash to implement Deep Reorg Protection. The new mechanism auto-finalizes a block once it has reached a depth of 10 and a time of 30 minutes has elapsed since the block header received time. This protects against large blockchain reorgs and also helps in faster transaction finalization. It ensures that even if an alternative chain has more proof of work and it conflicts with the last checkpoint, the node will not switch over to the most work chain. For more details check out our previous blog.

ASIC Resistance

An application-specific integrated circuit (ASIC) simply means a chip designed to do a particular task and nothing else. In the case of cryptocurrency, they are developed for a mining-specific algorithm. They are powerful, cost-effective and energy-efficient in terms of finding hashes. This means that using ASICs to mine Bitcoin or other Proof of Work cryptocurrencies is much better than using a general-purpose piece of hardware, such as a GPU card. This gives ASIC miners an unfair advantage over others in the mining landscape.

To avoid this and to make Zclassic ASIC resistant we changed the Equihash n,k parameters to 192 and 7 respectively. Earlier the parameters n,k used were 200,9 which was not ASIC resistant. The new Equihash algorithm prevents ASIC centralization by ensuring that the generation of proof is memory-intensive. Because memory is an expensive resource in computing, optimizing for memory on an ASIC chip will come at a large computational cost to the user.

Introducing Zclassic Simple Ledger Protocol

ZSLP is an emerging next-generation protocol for issuing and management of tokens on Zclassic blockchain. Storing and managing tokens on the blockchain provides greater auditability than traditional asset management and trading. Tokens can be used anywhere from rewarding your followers, to the creation of stocks, securities, registries, smart properties, utility tokens, contracts, coupons, bonds, demand deposits, local currencies, representation of physical assets, representation of individuals and much more. Tokens can be easily created, traded and managed on Zclassic blockchain within few seconds using Electrum ZSLP wallet or using mint.zslp.org

You can learn about creating ZSLP tokens using Electrum ZSLP wallet here

Electrum ZSLP Wallet

People have already started creating tokens and using them. At the time of writing this article, there are more than 670 ZSLP tokens on the Zclassic blockchain.

For more information check out our previous blog.

ZSLP Explorer

You can check and verify your ZSLP transactions using the explorer

mint.zslp.org web wallet

We also launched mint.zslp.org which is an open-source, non-custodial web wallet supporting ZSLP tokens and Zclassic

You can perform the following actions using the web wallet :

  • Create ZSLP token
  • Pay ZCL dividends to ZSLP token holders
  • Mint non-fixed/ fixed supply tokens
  • Send & Receive ZCL and ZSLP tokens
  • Import panda wallet

Panda Crypto Wallet

Panda Crypto Wallet is an open source, non-custodial, lightweight Zclassic wallet for android and iOS with support for ZSLP tokens. With its release, now it’s easier to receive and send ZCL and ZSLP tokens. This will help in driving adoption.

Panda Crypto Wallet on Android Play Store

What’s in the pipeline

Faster block time

This feature increases the frequency of blocks, allowing transactions to resolve faster. This will improve Zclassic’s usability and increase the number of transactions per hour the network can sustain while keeping transaction fees low. The current block time is 2.5 minutes and it will decrease to 1.25 minutes.

Triple Halving

With the support of Zclassic community and also to curb inflation, we have decided to go ahead with the Triple halving. Also, since Deep Reorg Protection is in place, Zclassic is more secure hence the miner incentive can be reduced.

  • Current Node Deprecation Block Height: 706992
  • Network Upgrade Block Height: 707000
  • Total Supply till Triple Halving Activation: 706999 * 12.5 = 8837487.5
  • New supply after Triple Halving (Four Halving and halved block time)
    Block subsidy after Triple Halving activation( every 1.25 mins): 0.78125
total = 0
block_subsidy = 0.78125
for i in range(5,64):
total += 840000 * 2 * block_subsidy
block_subsidy /= 2
2625000.0# 840000 is the old halving interval. Halving interval is doubled to account for the new halved block time
  • Old Total Supply: 21 Million
  • New Total Supply : 8837487.5 + 2625000 = 11462487.5 (~11.5 Million)


Bitcoin Script is very limited in usability and cannot be used to implement real-world financial instruments. To extend the Bitcoin Script to support validation of information outside the Zclassic blockchain, we are adding two new opcodes to the Bitcoin Script, OP_CHECKDATASIG and OP_CHECKDATASIGVERIFY respectively. This will open up a lot of opportunities for interesting smart contracts on Zclassic blockchain. Smart contracts along with ZSLP tokens will help developers create various financial instruments with ease. This will also drive the creation of various oracles for Zclassic blockchain. We are looking forward to the kind of applications, Zclassic community will create using smart contracts and ZSLP tokens.