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After a strong rally from the $6,000s, bitcoin ultimately saw a near 100% growth in market value as it now sits atop its rally in the low $11,000s. Currently, the market is testing well-known, strong resistance levels and is seeing quite turbulent shakeouts and rallies as it decides what the next market move will be. On a macro view, we can see that bitcoin is testing the strength of the daily 50 EMA:

Figure 1: BTC-USD, Daily Candles, Macro Trend

The red square at the top of the trend represents a macro distribution trading range that ultimately led to the decline in value of the last couple months. At the time of this article, we are currently testing the lower boundary of this trading range:

Figure 2: BTC-USD, 4-Hour Candles, Retest of Distribution Trading Range

In a typical markdown phase of a market cycle, it is quite common for a distribution trading range to break down through the bottom, see a strong drop in price, and then see a rally that leads to a retest of the lower limits of the prior distribution trading range.

The markdown from the top of the market cycle has been well defined by the red, dotted channel sloping downward in the image above. This current rally has the price pushing beyond the limits of the channel and shows a break of the current downward trend.

One thing that should be noted however is that a breakdown of a downward trend doesn’t necessarily mean that it will become an uptrend. It’s entirely possible that a break from the downward trend could lead into a consolidation period that yields a new downward trend — we’ve seen this time and time again.

At the time of this article we are currently seeing turbulent swings in price as the market decides what its next move will be. At the top of this rally from $6,000 to the $11,000s, we see a trading range starting to form:

Figure 3: BTC-USD, 30min Candles, Possible Trading Range

A bullish case for this trading range could be considered if we manage to break above it and find support on the top of the trading range. This sign of support would be a bullish signal to the market that we are no longer interested in lower values and that the market is ready to continue its markup campaign.

However, if we break above this trading range and fall back inside the trading range, it would be a very bearish sign that the we are actually forming another distribution trading range, indicating that the top of the current rally is over. At that point we could expect to begin a new markdown campaign in the following days and weeks.

Thus, this current resistance level is pivotal and will serve to mark either the end of the uptrend or the beginning of an even stronger move to higher values.

Summary:

1. Bitcoin has seen a strong rally since it bottomed out around $6,000.
   
2. Currently, it is finding turbulent market activity as it tests well-known and established resistance levels.
   
3. If we manage to find support on the trading range outlined in Figure 3, this will be a strong indication of a continuation to higher highs. However, if pushing upward we don’t find support on the top of the trading range and manage to fall back inside the trading range, this is a strong bearish signal that a potential markdown in price is in store in the next few days and weeks.
   

Trading and investing in digital assets like bitcoin and ether is highly speculative and comes with many risks. This analysis is for informational purposes and should not be considered investment advice. Statements and financial information on Bitcoin Magazine and BTC Media related sites do not necessarily reflect the opinion of BTC Media and should not be construed as an endorsement or recommendation to buy, sell or hold. Past performance is not necessarily indicative of future results.

On February 9, 2018, officials from U.S. Immigration and Customs Enforcement (ICE), the investigative arm of the Department of Homeland Security, arrested Morgan Rockcoons (aka “Morgan Rockwell” or “Metaballo”), CEO at Bitcoin, Inc. and an entrepreneur behind several other bitcoin startups, at his home in Las Vegas, Nevada.

Rockcoons was charged with money laundering and operating an unlicensed money transmitting business, according to court records.

According to those same records, in Southern California, between December 30, 2016 and January 8, 2017, Rockcoons allegedly exchanged around 10 bitcoin (worth around $9,200, at the time) for $14,500 in cash with an undercover law officer. That officer allegedly told Rockcoons in advance that the cash came from the manufacture and distribution of “hash oil,” which contains tetrahydrocannabinol, a controlled substance at the federal level.

Money laundering happens when a person takes ill-gotten money and turns it into “clean” money that cannot easily be tracked back to its source. Thus, if Rockcoons knew the cash was dirty, but traded it for bitcoin anyway, that would constitute money laundering.

Rockcoons was also allegedly operating an unlicensed money-transmitting business in Southern  California “from a date unknown” through August 30, 2017. Money transmitters are required to register with the Financial Crimes Enforcement Network (FinCEN).

The warrant for the arrest was issued by the Chief Magistrate for the Southern District of California on November 8, 2017, which indicates it may have taken authorities three months to track down Rockcoons, possibly because he moved out of the original jurisdiction.  

A Different Story

In private messages with Bitcoin Magazine and a series of public tweets, Rockcoons, who is actively seeking donations to pay for his legal fees, which he expects to be between $150,000 - $300,000, tells a different story than what is reflected in court records.

Where the court document says that the the cash given to him was already dirty, he claims that bitcoin he sold to the buyer became dirty after it left his hands.

“Someone bought a machine that makes cannabis oil with the BTC they purchased from me,” he said to Bitcoin Magazine. “I guess I'm not allowed to sell Bitcoin as a U.S. citizen for cash especially if [responsibility for] what people do with that money lies on me.”

In communication with Bitcoin Magazine, Rockcoons said that the buyer told him via text message that the bitcoins would be used to buy a “medical hash machine.”

He added, “Buying equipment in California is not illegal especially medical equipment in a medical State that's been a medical state for 25 years. [A] controlled substance does not have anything to do with the equipment because CBD oil can be extracted from Cannabis and that doesn't have anything to do with Tetra Hydro cannabinol.”

Both Rockcoons’ tweets and his subsequent communication with Bitcoin Magazine seemed to imply, initially, that he had no idea he was selling bitcoin to a law enforcement officer.

HashChain Technology Inc. (HashChain) has acquired the blockchain technology company NODE40 for $8 million USD and 3,144,134 common shares of stock in HashChain (TSXV: KASH) (OTCQB: HSSHF).

HashChain is a Canadian-based crypto-mining company that currently operates 100 Dash mining rigs and is in the process of setting up nearly 4,000 more to mine bitcoin. By locating in Canada, they are able to take advantage of both the very low electrical rates for power and the cool climate for data center cooling.

Having recently gone public on the TSX Venture Exchange, the company was looking to diversify their business beyond crypto-mining and have now acquired NODE40, a company that develops Software as a Service (SaaS) products related to cryptocurrency.

HashChain CEO and Founder Patrick Gray said, “The acquisition of the NODE40 Business is an important next step of creating a global blockchain technology company."

On the hardware and mining side, NODE40 runs a managed service for running your own Dash masternode. Masternodes get paid 45 percent of the monthly block reward as incentive for providing services to the network.

On the software side, NODE40 provides the SaaS product NODE40 Balance (Balance), which determines accurate valuations for each input/output involved in a user’s transaction by using cryptocurrency transaction history and analyzing the blockchain. Once a value is assigned to each transaction, then Balance will report the users’ current total asset value, income and any realized gains or loses.

"Cryptocurrency accounting and reporting for tax purposes is a major concern in the industry at the moment,” said Gray. “The recent Coinbase subpoena from the IRS highlights the significant need for the software developed by NODE40."

The acquisition was finalized on February 15, 2018.

Corporates, suits and CEOs of traditional companies beware: decentralized protocols powered by blockchain technology are redefining your traditional business models, and you should be worried. Business models of the future are not created equal, and they certainly don’t play by the same rules. In the Venn Diagram of traditional business and decentralized protocols, there are a few overlaps and many differences.

Traditional Businesses vs. Decentralized Protocols

Boiled down to the most simple terms, all traditional businesses are organizations that charge customers a certain price (usually denoted in fiat currency) in exchange for a certain product or service. Starbucks charges $3.28 for a quad, grande, decaf Americano. Netflix charges a monthly $10.99 for unlimited Nicolas Cage streaming. Lover’s charges $20 to “spice things up” in the bedroom.

Ultimately, all traditional businesses –– no matter the product or service –– are driven by the quest for profit. Business owners are incentivized to reduce costs, increase efficiencies and scale carefully to maximize cash flows for shareholders.

The key stakeholders of traditional business are customers, business owners/employees and business financiers.

A decentralized protocol powered by blockchain technology is a network — a network framed by cryptography, distributed ledger technology, decentralization and consensus methods –– but a network nonetheless. The networks created by decentralized protocols aren’t structured like the networks created by any traditional business model.

Decentralized protocols aren’t driven by the need to create future cash flows for shareholders. Instead, they are programmed to facilitate commercial interactions between humans in a frictionless manner. A protocol’s incentives are aligned to benefit users and to achieve the smallest margins possible.

The key stakeholders of decentralized protocols are customers, protocol “community maintainers” and (occasionally) protocol financiers.

Customers

Customers benefit from the traditional business they choose to interact with. For a price specified by the business (in fiat currency), they are entitled to a product or service.

Similarly, customers benefit from the protocol they choose to interact with. For a price specified by the protocol, they are entitled to a product or service.

Generally, protocols are powered by utility tokens. For example, the fictional Planes Protocol facilitates coast-to-coast trips in a Tesla-of-the-skies (electric planes) for 1 PLN token. The PLN token is a medium-of-exchange. Nick, a businessman from Seattle, must pay 1 PLN token for a flight from Seattle to Miami. The plane operator is entitled to 99 percent of the PLN token fee and the Planes Protocol claims the other 1 percent.

Business Owners and Employees

Traditional business owners and employees must be compensated for their work. After all, there is a price to pay for food, water and shelter. Business owners pay themselves with portions of their revenue and pay their employees salaries for their work.

Because protocols are decentralized, the concept of “business owner” does not apply. Instead, protocols are cultivated by those designated as “community maintainers.” Whether the protocol founder is designated as the “community maintainer” is up to the community.

Protocols can facilitate commercial interactions between humans “at cost,” as long as they are generating enough in network fees to cover all required upkeep costs. For example, these can include a centralized unit to guarantee customer satisfaction and hiring of developers, project managers or anyone else necessary to keep the network alive and well. Therefore, a protocol’s margins can be much lower than that of a traditional business.

If a “greedy” protocol is programmed with transaction fees that are unreasonably high, anyone can “fork” the protocol (by using a modified copy of the original open-source code) and create a competing network with lower transaction fees. This will continue until price reaches a near-free equilibrium.

Protocol founders can reward themselves with a certain percentage of all tokens ever minted for creating the protocol; similarly, “community maintainers” are rewarded for their efforts via the protocol’s tokens on an ongoing, salary-style basis. These tokens usually have a related fiat value and can be redeemed on publicly traded exchanges.

Side note: Utility tokens are not a panacea. They face various problems such as publicly traded speculation and token velocity. A utopian, token-centric future will not happen overnight. There is much work to do.

Business Financiers

Many business owners or entrepreneurs traditionally rely on risk-tolerant financiers with capital. In the 1500s, enterprising trade voyagers relied on wealthy financiers to support their journeys. If trade voyagers were successful, financiers earned the lion’s share of the voyagers’ profits.

In 2018, Silicon Valley startup founders relinquish equity/control over their company to venture capitalists (modern day trade financiers) in exchange for seed funding. If startups are successful, venture capitalists earn a return proportional to their shares of the company.

It is important to note that capitalism and traditional business models work well. There are millions of happy customers across a variety of industries. But, in some cases, decentralized protocols provide cheaper access to products or services and better-aligned incentives for all stakeholders.

Founders of protocols have flexibility. Because they are creating a new network powered by utility tokens, they can afford to bypass traditional debt/equity financing.

While 16th century merchants and past Silicon Valley founders played by the rules of their financiers, founders of decentralized protocols are freed from this sort of pressure. Protocols can crowdfund capital by pre-selling their protocol’s utility tokens to accredited VCs and, in some cases, to the general public. Protocols can also give discounted tokens to developers for their skills.

Key Takeaway: Traditional businesses and protocols are not created equal. And decentralized protocols certainly don’t play by the same rules as traditional businesses.

Shifting the Value Paradigm

So, what might value creation in the future even look like? And how does a legacy business survive the decentralized future?

Corporate decision-makers must recognize and understand that:

• This is a true instance of the often-overlooked “past performance is no guarantee of future results.” Traditional business models cannot be confused with or compared to protocols of the future.
  
• Decentralized protocols of the Web 3.0 will not automatically dethrone legacy businesses. And, in some cases, traditional business would not benefit from decentralization. Protocols will not gain the necessary network effects for widespread adoption unless their value proposition is an order of magnitude better than current business models.
  
• If your corporation operates on the basis of artificial scarcity or “middlemen economics,” you’re ripe for disruption.
  

Most decentralized protocols still require certain aspects of centralization to guarantee customer satisfaction. Sorry, libertarians, but certain things must maintain a degree of centralization.

Practical Example: Uber vs. Ride, a Fictional, Decentralized Ride-Sharing Protocol.

In 2018, Uber has 3 key competitive advantages in the ride-sharing market:

1. Legacy Network: ~ 40 million total monthly, active riders; ~ 1.5 million total drivers
   
2. Customer Satisfaction Guarantee: a centralized company able to provide riders/drivers with personalized troubleshooting. For example, when a driver complains that a college student threw up in his Uber, the centralized Uber troubleshooting authority reprimands the rider in the form of a citation and makes the driver whole.
   
3. Brand Name Recognition: Uber has achieved ultimate “verb” status. On par with “Googling” something.
   

However, in 5–20 years, Ride will inevitably come along and attempt to win over Uber’s users and drivers. Ride won’t be structured like Uber’s traditional business model. Its goal won’t be to create future cash flows for Ride shareholders. Instead, the protocol will focus on facilitating transactions between riders and drivers in a frictionless, decentralized manner. Ride’s incentives will be aligned to benefit riders and drivers.

Because Ride isn’t driven by the quest for profit, it doesn’t have to charge drivers ~20 percent for each ride. Instead, they can charge users/drivers fractional transaction fees (by means of the RIDE utility token) for interacting with the protocol. These transaction fees are used to maintain and secure the Ride protocol.

The Ride protocol will raise money by pre-selling their utility tokens via decentralized crowdfunding. The protocol will provide an order of magnitude improvement over Uber’s network, executed by the right team and the right investors. Because of this, Ride will amass a significant network effect, user base and brand name recognition. Of course, the Ride protocol will likely still have aspects of centralization to provide customer satisfaction.

So, How Can Companies Like Uber Survive in 2025?

There are two options:

1. “Reverse ICO,” or create a decentralized protocol for the service you provide.
   
2. Slowly go bankrupt as market share is taken away by your competitors, who are decentralized protocols.
   

Decentralization will be just one of many difficult topics to bring up at a board meeting. After all, artificial intelligence and automation are advancing every year. Shrinking margins, employee layoffs and re-trainings are also implicit with decentralization. (Maybe it’s best to recruit your interns to volunteer this information to the board, in case this inevitability isn’t well-received by your shareholders.)

Legacy companies are presented with an incredible opportunity to participate in the next evolution of business models and commercial interactions between people. Choose to embrace the future or fall as a victim to social darwinism: the choice is up to you.

This is an opinion piece by Erik Kuebler. The views expressed are his own and do not necessarily reflect those of BTC Media or Bitcoin Magazine.

New blockchains are born all the time. Bitcoin was the lone blockchain for years, but now there are hundreds. The problem is, if you want to use the features offered on another blockchain, you have to buy the tokens for that other blockchain.

But all that may soon change. One developing technology called sidechains promises to make it easier to move tokens across blockchains and, as a result, open the doors to a world of possibilities, including building bridges to the legacy financial systems of banks.

In October 2017, Aggelos Kiayias, professor at the University of Edinburgh and chief scientist at blockchain research and development company IOHK; Andrew Miller, professor at the University of Illinois at Urbana-Champaign; and Dionysis Zindros, researcher at the University of Athens, released the paper “Non-Interactive Proofs of Proof-of-Work” (NiPoPoW), introducing a critical piece to the sidechains puzzle that had been missing for three years. This is the story of how they got there.

But, first, what exactly is a sidechain?    

Same Coin, Different Blockchain

A sidechain is a technology that allows you to move your tokens from one blockchain to another, use them on that other blockchain and then move them back at a later point in time, without the need for a third party.  

In the past, the parent blockchain has typically been Bitcoin, but a parent chain could be any blockchain. Also, when a token moves to another blockchain, it should maintain its same value. In other words, a bitcoin on an Ethereum sidechain would remain a bitcoin.  

The biggest advantage of sidechains is that they would allow users to access a host of new services. For instance, you could move bitcoin to another blockchain to take advantage of privacy features, faster transaction speeds and smart contracts.  

Sidechains have other uses, too. A sidechain could offer a more secure way to upgrade a protocol, or it could serve as a type of security firewall, so that in the event of a catastrophic disaster on a sidechain, the main chain would remain unaffected. “It is a kind of limited liability,” said Zindros in a video explaining how the technology works.

Finally, if banks were to create their own private blockchain networks, sidechains could enable communications with those networks, allowing users to issue and track shares, bonds and other assets.

Early Conversations

Early dialogue about sidechains first appeared in Bitcoin chat rooms around 2012, when Bitcoin Core developers were thinking of ways to safely upgrade the Bitcoin protocol.

One idea was for a “one-way peg,” where users could move bitcoin to a separate blockchain to test out a new client; however, once those assets were moved, they could not be moved back to the main chain.  

“I was thinking of this as a software engineering tool that could be used to make widespread changes,” Adam Back, now CEO at blockchain development company Blockstream, said in an interview with Bitcoin Magazine. “You could say, we are going to make a new version [of Bitcoin], and we think it will be ready in a year, but in the meantime, you can opt in early and test it.”

According to Back, sometime in the following year, on the Bitcoin IRC channel, Bitcoin Core developer Greg Maxwell suggested an idea for a “two-way peg,” where value could be transferred to the alternative chain and then back to Bitcoin at a later point.

A two-way peg addressed another growing concern at the time. Alternative coins, like Litecoin and Namecoin, were becoming increasingly popular. The fear was these “altcoins” would dilute the value of bitcoin. It made sense, Bitcoin Core developers thought, to keep bitcoin as a type of reserve currency, and relegate new features to sidechains. That way, “if you wanted to use a different feature, you wouldn’t have to buy a speculative asset,” said Back.

To turn the concept of sidechains into a reality, Back along with Maxwell and a few other Bitcoin Core developers formed Blockstream in 2014. In October that year, the group released “Enabling Blockchain Innovations with Pegged Sidechains,” a paper describing sidechains at a high level. Miller appears as a co-author on that paper as well.

How Sidechains Work

One important component of sidechains is a simplified payment verification (SPV) proof that shows that tokens have been locked up on one chain so validators can safely unlock an equivalent value on the alternative chain. But to work for sidechains, an SPV proof has to be small enough to fit into a single coinbase transaction, the transaction that rewards a miner with new coins. (Not to be confused with the company Coinbase.)

At the time the Blockstream researchers released their paper, they knew they needed a compressed SPV proof to get sidechains to work, but they had not yet developed the cryptography behind it. So they outlined general, high-level ideas.

The Blockstream paper describes two types of two-way pegs: a symmetric two-way peg, where both chains are independent with their own mining; and an asymmetric two-way peg, where sidechain miners are full validators of the parent chain.

In a symmetric two-way peg, a user sends her bitcoins to a special address. Doing so locks up the funds on the Bitcoin blockchain. That output remains locked for a contest period of maybe six blocks (one hour) to confirm the transaction has gone through, and then an SPV proof is created to send to the sidechain.

At that point, a corresponding transaction appears on the sidechain with the SPV proof, verifying that money has been locked up on the Bitcoin blockchain, and then coins with the same value of account are unlocked on the sidechain.

Coins are spent and change hands and, at a later point, are sent back to the main chain. When the coins are returned to the main chain, the process repeats. They are sent to a locked output on the sidechain, a waiting period goes by, and an SPV proof is created and sent back to the main blockchain to unlock coins on the main chain.  

In an asymmetric two-way peg, the process is slightly different. The transfer from the parent chain to the sidechain does not require an SPV proof, because validators on the sidechain are also aware of the state of the parent chain. An SPV proof is still needed, however, when the coins are returned to the parent chain.

The Search for a Compact Proof

In a sidechain, a compact SPV proof needs to contain a compressed version of all the block headers in the chain where funds are locked up from the genesis block through the contest period, as well as transaction data and some other data. In this way, an SPV proof can also be thought of as a “proof of proof-of-work” for a particular output.

Inspiration for the compact SPV proof comes from a linked-list-like structure known as a “skip list” developed 25 years ago. In applying this structure to a compact SPV proof, the trick was in finding a way to skip block headers while still maintaining a high level of security so that an adversary would not be able to fake a proof.

In working through the problem, Blockstream showed an early draft of its sidechains paper to Miller, who had been mulling over compact SPVs for a few years already.

In August 2012, in a post on a BitcoinTalk forum titled “The High-Value-Hash Highway,” Miller described an idea for a “merkle skip list” that a Bitcoin light client could use to quickly determine the longest chain and begin using it. In that post, he described the significance of the data structure as “absolutely staggering.”

When Miller read through the Blockstream draft, he spotted a vulnerability in the compact SPV proof described in the paper. Discussions ensued, but they “couldn’t find a way to solve that problem without compromising efficiency,” Miller said.

Miller’s non-trivial contributions to the Blockstream paper ended up being a few paragraphs in Appendix B that describe the challenges in creating a compact SPV proof.

It should “be possible to greatly compress a list of headers while still proving the same amount of work,” the section reads, but “optimising these tradeoffs and formalising the security guarantees is out of scope for this paper and the topic of ongoing work.”

That ongoing work remained stuck for three years.

Compact SPV

During that ensuing time, researchers at IOHK began taking a more serious interest in sidechains. Plans were taking shape for Cardano, a new proof-of-stake blockchain that IOHK had been contracted to build.

Cardano would consist of two layers: a settlement layer, launched in September 2017, where the money supply would be kept, and a smart contract layer. Those two layers would be two sidechain-enabled blockchains. In this way, the settlement could remain simple and secure from any attacks that might occur on the smart contract layer. But if IOHK was to get Cardano to work as intended, it needed to solve sidechains.

In February 2016, Kiayias, then a professor at the University of Athens, and two of his students, Nikolaos Lamprou and Aikaterini-Panagiota Stouka, released “Proofs of Proofs of Work with Sublinear Complexity” (PoPoW).

The paper was the first to formally address a compact SPV proof. Only, the proof described in the paper was interactive; whereas, to work for sidechains, it needed to be non-interactive.

In an interactive proof, the prover and the verifier enter into a back-and-forth conversation, meaning there could be more than one round of messaging. In contrast, a non-interactive proof would be a simple, short string of text that would fit neatly into a single transaction on the blockchain.

The PoPoW paper was presented at BITCOIN’16, a workshop affiliated with the International Financial Cryptography Association’s (IFCA) Financial Cryptography and Data Security conference. Miller, who was at the conference, approached Kiayias and shared an idea for making the protocol non-interactive.

It was a “nice observation,” Kiayias told Bitcoin Magazine, but making the proof secure was “not obvious at all” and would require significant work.

Zindros, who had just started working on his PhD under Kiayias, was also at the conference, and he needed a topic for his thesis. Kiayias saw a good fit, “so we pressed on, the three of us, and adapted the PoPoW protocol and its proof of security to the non-interactive setting,” Kiayias said.

In October 2016, Kiayias officially joined IOHK, and a year later, Kiayias, Miller and Zindros released “Non-Interactive Proofs of Proof-of-Work,” introducing a compact SPV proof five years after sidechains had first been talked about on Bitcoin forums.

“If it were interactive, I don’t know if it would have worked; with a non-interactive proof, it is really smooth,” Zindros told Bitcoin Magazine.

More Work to Be Done

Even with NiPoPoW, sidechains are still not fully specified. Several questions remain, including, how small can the proofs be made? After a transaction is locked up on one chain, how much time needs to pass before it can be spent on the other? And, will it be possible to move a token from a sidechain directly to another sidechain?

“A lot of theory still needs to be defined,” IOHK CEO Charles Hoskinson said in speaking to Bitcoin Magazine.

Also, while NiPoPoW is designed to work for proof-of-work blockchains, some believe that if blockchains are to take their place in the world on a grand scale, the future rests in proof-of-stake protocols like Ouroboros, Algorand or Snow White, which promise to be more energy-efficient than Bitcoin.

In particular, if Cardano, which is based on Ouroboros, is to work according to plan, IOHK researchers still need to discover a non-interactive proof of proof-of-stake (NiPoPoS).

Hoskinson is confident. “We can definitely do that,” he said. “We can definitely have a NiPoPoS. The question is how many megabytes or kilobytes is it going to be? Can we bring it down to 100 KB? That is really the question.”

New blockchains are born all the time. Bitcoin was the lone blockchain for years, but now there are hundreds. The problem is, if you want to use the features offered on another blockchain, you have to buy the tokens for that other blockchain.

But all that may soon change. One developing technology called sidechains promises to make it easier to move tokens across blockchains and, as a result, open the doors to a world of possibilities, including building bridges to the legacy financial systems of banks.

In October 2017, Aggelos Kiayias, professor at the University of Edinburgh and chief scientist at blockchain research and development company IOHK; Andrew Miller, professor at the University of Illinois at Urbana-Champaign; and Dionysis Zindros, researcher at the University of Athens, released the paper “Non-Interactive Proofs of Proof-of-Work” (NiPoPoW), introducing a critical piece to the sidechains puzzle that had been missing for three years. This is the story of how they got there.

But, first, what exactly is a sidechain?    

Same Coin, Different Blockchain

A sidechain is a technology that allows you to move your tokens from one blockchain to another, use them on that other blockchain and then move them back at a later point in time, without the need for a third party.  

In the past, the parent blockchain has typically been Bitcoin, but a parent chain could be any blockchain. Also, when a token moves to another blockchain, it should maintain its same value. In other words, a bitcoin on an Ethereum sidechain would remain a bitcoin.  

The biggest advantage of sidechains is that they would allow users to access a host of new services. For instance, you could move bitcoin to another blockchain to take advantage of privacy features, faster transaction speeds and smart contracts.  

Sidechains have other uses, too. A sidechain could offer a more secure way to upgrade a protocol, or it could serve as a type of security firewall, so that in the event of a catastrophic disaster on a sidechain, the main chain would remain unaffected. “It is a kind of limited liability,” said Zindros in a video explaining how the technology works.

Finally, if banks were to create their own private blockchain networks, sidechains could enable communications with those networks, allowing users to issue and track shares, bonds and other assets.

Early Conversations

Early dialogue about sidechains first appeared in Bitcoin chat rooms around 2012, when Bitcoin Core developers were thinking of ways to safely upgrade the Bitcoin protocol.

One idea was for a “one-way peg,” where users could move bitcoin to a separate blockchain to test out a new client; however, once those assets were moved, they could not be moved back to the main chain.  

“I was thinking of this as a software engineering tool that could be used to make widespread changes,” Adam Back, now CEO at blockchain development company Blockstream, said in an interview with Bitcoin Magazine. “You could say, we are going to make a new version [of Bitcoin], and we think it will be ready in a year, but in the meantime, you can opt in early and test it.”

According to Back, sometime in the following year, on the Bitcoin IRC channel, Bitcoin Core developer Greg Maxwell suggested an idea for a “two-way peg,” where value could be transferred to the alternative chain and then back to Bitcoin at a later point.

A two-way peg addressed another growing concern at the time. Alternative coins, like Litecoin and Namecoin, were becoming increasingly popular. The fear was these “altcoins” would dilute the value of bitcoin. It made sense, Bitcoin Core developers thought, to keep bitcoin as a type of reserve currency, and relegate new features to sidechains. That way, “if you wanted to use a different feature, you wouldn’t have to buy a speculative asset,” said Back.

To turn the concept of sidechains into a reality, Back along with Maxwell and a few other Bitcoin Core developers formed Blockstream in 2014. In October that year, the group released “Enabling Blockchain Innovations with Pegged Sidechains,” a paper describing sidechains at a high level. Miller appears as a co-author on that paper as well.

How Sidechains Work

One important component of sidechains is a simplified payment verification (SPV) proof that shows that tokens have been locked up on one chain so validators can safely unlock an equivalent value on the alternative chain. But to work for sidechains, an SPV proof has to be small enough to fit into a single coinbase transaction, the transaction that rewards a miner with new coins. (Not to be confused with the company Coinbase.)

At the time the Blockstream researchers released their paper, they knew they needed a compressed SPV proof to get sidechains to work, but they had not yet developed the cryptography behind it. So they outlined general, high-level ideas.

The Blockstream paper describes two types of two-way pegs: a symmetric two-way peg, where both chains are independent with their own mining; and an asymmetric two-way peg, where sidechain miners are full validators of the parent chain.

In a symmetric two-way peg, a user sends her bitcoins to a special address. Doing so locks up the funds on the Bitcoin blockchain. That output remains locked for a contest period of maybe six blocks (one hour) to confirm the transaction has gone through, and then an SPV proof is created to send to the sidechain.

At that point, a corresponding transaction appears on the sidechain with the SPV proof, verifying that money has been locked up on the Bitcoin blockchain, and then coins with the same value of account are unlocked on the sidechain.

Coins are spent and change hands and, at a later point, are sent back to the main chain. When the coins are returned to the main chain, the process repeats. They are sent to a locked output on the sidechain, a waiting period goes by, and an SPV proof is created and sent back to the main blockchain to unlock coins on the main chain.  

In an asymmetric two-way peg, the process is slightly different. The transfer from the parent chain to the sidechain does not require an SPV proof, because validators on the sidechain are also aware of the state of the parent chain. An SPV proof is still needed, however, when the coins are returned to the parent chain.

The Search for a Compact Proof

In a sidechain, a compact SPV proof needs to contain a compressed version of all the block headers in the chain where funds are locked up from the genesis block through the contest period, as well as transaction data and some other data. In this way, an SPV proof can also be thought of as a “proof of proof-of-work” for a particular output.

Inspiration for the compact SPV proof comes from a linked-list-like structure known as a “skip list” developed 25 years ago. In applying this structure to a compact SPV proof, the trick was in finding a way to skip block headers while still maintaining a high level of security so that an adversary would not be able to fake a proof.

In working through the problem, Blockstream showed an early draft of its sidechains paper to Miller, who had been mulling over compact SPVs for a few years already.

In August 2012, in a post on a BitcoinTalk forum titled “The High-Value-Hash Highway,” Miller described an idea for a “merkle skip list” that a Bitcoin light client could use to quickly determine the longest chain and begin using it. In that post, he described the significance of the data structure as “absolutely staggering.”

When Miller read through the Blockstream draft, he spotted a vulnerability in the compact SPV proof described in the paper. Discussions ensued, but they “couldn’t find a way to solve that problem without compromising efficiency,” Miller said.

Miller’s non-trivial contributions to the Blockstream paper ended up being a few paragraphs in Appendix B that describe the challenges in creating a compact SPV proof.

It should “be possible to greatly compress a list of headers while still proving the same amount of work,” the section reads, but “optimising these tradeoffs and formalising the security guarantees is out of scope for this paper and the topic of ongoing work.”

That ongoing work remained stuck for three years.

Compact SPV

During that ensuing time, researchers at IOHK began taking a more serious interest in sidechains. Plans were taking shape for Cardano, a new proof-of-stake blockchain that IOHK had been contracted to build.

Cardano would consist of two layers: a settlement layer, launched in September 2017, where the money supply would be kept, and a smart contract layer. Those two layers would be two sidechain-enabled blockchains. In this way, the settlement could remain simple and secure from any attacks that might occur on the smart contract layer. But if IOHK was to get Cardano to work as intended, it needed to solve sidechains.

In February 2016, Kiayias, then a professor at the University of Athens, and two of his students, Nikolaos Lamprou and Aikaterini-Panagiota Stouka, released “Proofs of Proofs of Work with Sublinear Complexity” (PoPoW).

The paper was the first to formally address a compact SPV proof. Only, the proof described in the paper was interactive; whereas, to work for sidechains, it needed to be non-interactive.

In an interactive proof, the prover and the verifier enter into a back-and-forth conversation, meaning there could be more than one round of messaging. In contrast, a non-interactive proof would be a simple, short string of text that would fit neatly into a single transaction on the blockchain.

The PoPoW paper was presented at BITCOIN’16, a workshop affiliated with the International Financial Cryptography Association’s (IFCA) Financial Cryptography and Data Security conference. Miller, who was at the conference, approached Kiayias and shared an idea for making the protocol non-interactive.

It was a “nice observation,” Kiayias told Bitcoin Magazine, but making the proof secure was “not obvious at all” and would require significant work.

Zindros, who had just started working on his PhD under Kiayias, was also at the conference, and he needed a topic for his thesis. Kiayias saw a good fit, “so we pressed on, the three of us, and adapted the PoPoW protocol and its proof of security to the non-interactive setting,” Kiayias said.

In October 2016, Kiayias officially joined IOHK, and a year later, Kiayias, Miller and Zindros released “Non-Interactive Proofs of Proof-of-Work,” introducing a compact SPV proof five years after sidechains had first been talked about on Bitcoin forums.

“If it were interactive, I don’t know if it would have worked; with a non-interactive proof, it is really smooth,” Zindros told Bitcoin Magazine.

More Work to Be Done

Even with NiPoPoW, sidechains are still not fully specified. Several questions remain, including, how small can the proofs be made? After a transaction is locked up on one chain, how much time needs to pass before it can be spent on the other? And, will it be possible to move a token from a sidechain directly to another sidechain?

“A lot of theory still needs to be defined,” IOHK CEO Charles Hoskinson said in speaking to Bitcoin Magazine.

Also, while NiPoPoW is designed to work for proof-of-work blockchains, some believe that if blockchains are to take their place in the world on a grand scale, the future rests in proof-of-stake protocols like Ouroboros, Algorand or Snow White, which promise to be more energy-efficient than Bitcoin.

In particular, if Cardano, which is based on Ouroboros, is to work according to plan, IOHK researchers still need to discover a non-interactive proof of proof-of-stake (NiPoPoS).

Hoskinson is confident. “We can definitely do that,” he said. “We can definitely have a NiPoPoS. The question is how many megabytes or kilobytes is it going to be? Can we bring it down to 100 KB? That is really the question.”

New blockchains are born all the time. Bitcoin was the lone blockchain for years, but now there are hundreds. The problem is, if you want to use the features offered on another blockchain, you have to buy the tokens for that other blockchain.

But all that may soon change. One developing technology called sidechains promises to make it easier to move tokens across blockchains and, as a result, open the doors to a world of possibilities, including building bridges to the legacy financial systems of banks.

In October 2017, Aggelos Kiayias, professor at the University of Edinburgh and chief scientist at blockchain research and development company IOHK; Andrew Miller, professor at the University of Illinois at Urbana-Champaign; and Dionysis Zindros, researcher at the University of Athens, released the paper “Non-Interactive Proofs of Proof-of-Work” (NiPoPoW), introducing a critical piece to the sidechains puzzle that had been missing for three years. This is the story of how they got there.

But, first, what exactly is a sidechain?    

Same Coin, Different Blockchain

A sidechain is a technology that allows you to move your tokens from one blockchain to another, use them on that other blockchain and then move them back at a later point in time, without the need for a third party.  

In the past, the parent blockchain has typically been Bitcoin, but a parent chain could be any blockchain. Also, when a token moves to another blockchain, it should maintain its same value. In other words, a bitcoin on an Ethereum sidechain would remain a bitcoin.  

The biggest advantage of sidechains is that they would allow users to access a host of new services. For instance, you could move bitcoin to another blockchain to take advantage of privacy features, faster transaction speeds and smart contracts.  

Sidechains have other uses, too. A sidechain could offer a more secure way to upgrade a protocol, or it could serve as a type of security firewall, so that in the event of a catastrophic disaster on a sidechain, the main chain would remain unaffected. “It is a kind of limited liability,” said Zindros in a video explaining how the technology works.

Finally, if banks were to create their own private blockchain networks, sidechains could enable communications with those networks, allowing users to issue and track shares, bonds and other assets.

Early Conversations

Early dialogue about sidechains first appeared in Bitcoin chat rooms around 2012, when Bitcoin Core developers were thinking of ways to safely upgrade the Bitcoin protocol.

One idea was for a “one-way peg,” where users could move bitcoin to a separate blockchain to test out a new client; however, once those assets were moved, they could not be moved back to the main chain.  

“I was thinking of this as a software engineering tool that could be used to make widespread changes,” Adam Back, now CEO at blockchain development company Blockstream, said in an interview with Bitcoin Magazine. “You could say, we are going to make a new version [of Bitcoin], and we think it will be ready in a year, but in the meantime, you can opt in early and test it.”

According to Back, sometime in the following year, on the Bitcoin IRC channel, Bitcoin Core developer Greg Maxwell suggested an idea for a “two-way peg,” where value could be transferred to the alternative chain and then back to Bitcoin at a later point.

A two-way peg addressed another growing concern at the time. Alternative coins, like Litecoin and Namecoin, were becoming increasingly popular. The fear was these “altcoins” would dilute the value of bitcoin. It made sense, Bitcoin Core developers thought, to keep bitcoin as a type of reserve currency, and relegate new features to sidechains. That way, “if you wanted to use a different feature, you wouldn’t have to buy a speculative asset,” said Back.

To turn the concept of sidechains into a reality, Back along with Maxwell and a few other Bitcoin Core developers formed Blockstream in 2014. In October that year, the group released “Enabling Blockchain Innovations with Pegged Sidechains,” a paper describing sidechains at a high level. Miller appears as a co-author on that paper as well.

How Sidechains Work

One important component of sidechains is a simplified payment verification (SPV) proof that shows that tokens have been locked up on one chain so validators can safely unlock an equivalent value on the alternative chain. But to work for sidechains, an SPV proof has to be small enough to fit into a single coinbase transaction, the transaction that rewards a miner with new coins. (Not to be confused with the company Coinbase.)

At the time the Blockstream researchers released their paper, they knew they needed a compressed SPV proof to get sidechains to work, but they had not yet developed the cryptography behind it. So they outlined general, high-level ideas.

The Blockstream paper describes two types of two-way pegs: a symmetric two-way peg, where both chains are independent with their own mining; and an asymmetric two-way peg, where sidechain miners are full validators of the parent chain.

In a symmetric two-way peg, a user sends her bitcoins to a special address. Doing so locks up the funds on the Bitcoin blockchain. That output remains locked for a contest period of maybe six blocks (one hour) to confirm the transaction has gone through, and then an SPV proof is created to send to the sidechain.

At that point, a corresponding transaction appears on the sidechain with the SPV proof, verifying that money has been locked up on the Bitcoin blockchain, and then coins with the same value of account are unlocked on the sidechain.

Coins are spent and change hands and, at a later point, are sent back to the main chain. When the coins are returned to the main chain, the process repeats. They are sent to a locked output on the sidechain, a waiting period goes by, and an SPV proof is created and sent back to the main blockchain to unlock coins on the main chain.  

In an asymmetric two-way peg, the process is slightly different. The transfer from the parent chain to the sidechain does not require an SPV proof, because validators on the sidechain are also aware of the state of the parent chain. An SPV proof is still needed, however, when the coins are returned to the parent chain.

The Search for a Compact Proof

In a sidechain, a compact SPV proof needs to contain a compressed version of all the block headers in the chain where funds are locked up from the genesis block through the contest period, as well as transaction data and some other data. In this way, an SPV proof can also be thought of as a “proof of proof-of-work” for a particular output.

Inspiration for the compact SPV proof comes from a linked-list-like structure known as a “skip list” developed 25 years ago. In applying this structure to a compact SPV proof, the trick was in finding a way to skip block headers while still maintaining a high level of security so that an adversary would not be able to fake a proof.

In working through the problem, Blockstream showed an early draft of its sidechains paper to Miller, who had been mulling over compact SPVs for a few years already.

In August 2012, in a post on a BitcoinTalk forum titled “The High-Value-Hash Highway,” Miller described an idea for a “merkle skip list” that a Bitcoin light client could use to quickly determine the longest chain and begin using it. In that post, he described the significance of the data structure as “absolutely staggering.”

When Miller read through the Blockstream draft, he spotted a vulnerability in the compact SPV proof described in the paper. Discussions ensued, but they “couldn’t find a way to solve that problem without compromising efficiency,” Miller said.

Miller’s non-trivial contributions to the Blockstream paper ended up being a few paragraphs in Appendix B that describe the challenges in creating a compact SPV proof.

It should “be possible to greatly compress a list of headers while still proving the same amount of work,” the section reads, but “optimising these tradeoffs and formalising the security guarantees is out of scope for this paper and the topic of ongoing work.”

That ongoing work remained stuck for three years.

Compact SPV

During that ensuing time, researchers at IOHK began taking a more serious interest in sidechains. Plans were taking shape for Cardano, a new proof-of-stake blockchain that IOHK had been contracted to build.

Cardano would consist of two layers: a settlement layer, launched in September 2017, where the money supply would be kept, and a smart contract layer. Those two layers would be two sidechain-enabled blockchains. In this way, the settlement could remain simple and secure from any attacks that might occur on the smart contract layer. But if IOHK was to get Cardano to work as intended, it needed to solve sidechains.

In February 2016, Kiayias, then a professor at the University of Athens, and two of his students, Nikolaos Lamprou and Aikaterini-Panagiota Stouka, released “Proofs of Proofs of Work with Sublinear Complexity” (PoPoW).

The paper was the first to formally address a compact SPV proof. Only, the proof described in the paper was interactive; whereas, to work for sidechains, it needed to be non-interactive.

In an interactive proof, the prover and the verifier enter into a back-and-forth conversation, meaning there could be more than one round of messaging. In contrast, a non-interactive proof would be a simple, short string of text that would fit neatly into a single transaction on the blockchain.

The PoPoW paper was presented at BITCOIN’16, a workshop affiliated with the International Financial Cryptography Association’s (IFCA) Financial Cryptography and Data Security conference. Miller, who was at the conference, approached Kiayias and shared an idea for making the protocol non-interactive.

It was a “nice observation,” Kiayias told Bitcoin Magazine, but making the proof secure was “not obvious at all” and would require significant work.

Zindros, who had just started working on his PhD under Kiayias, was also at the conference, and he needed a topic for his thesis. Kiayias saw a good fit, “so we pressed on, the three of us, and adapted the PoPoW protocol and its proof of security to the non-interactive setting,” Kiayias said.

In October 2016, Kiayias officially joined IOHK, and a year later, Kiayias, Miller and Zindros released “Non-Interactive Proofs of Proof-of-Work,” introducing a compact SPV proof five years after sidechains had first been talked about on Bitcoin forums.

“If it were interactive, I don’t know if it would have worked; with a non-interactive proof, it is really smooth,” Zindros told Bitcoin Magazine.

More Work to Be Done

Even with NiPoPoW, sidechains are still not fully specified. Several questions remain, including, how small can the proofs be made? After a transaction is locked up on one chain, how much time needs to pass before it can be spent on the other? And, will it be possible to move a token from a sidechain directly to another sidechain?

“A lot of theory still needs to be defined,” IOHK CEO Charles Hoskinson said in speaking to Bitcoin Magazine.

Also, while NiPoPoW is designed to work for proof-of-work blockchains, some believe that if blockchains are to take their place in the world on a grand scale, the future rests in proof-of-stake protocols like Ouroboros, Algorand or Snow White, which promise to be more energy-efficient than Bitcoin.

In particular, if Cardano, which is based on Ouroboros, is to work according to plan, IOHK researchers still need to discover a non-interactive proof of proof-of-stake (NiPoPoS).

Hoskinson is confident. “We can definitely do that,” he said. “We can definitely have a NiPoPoS. The question is how many megabytes or kilobytes is it going to be? Can we bring it down to 100 KB? That is really the question.”