Earth Day & MobileCoin: Be Green when you Send Green

It’s time to support our planet for Earth Day and examine the environmental impact of our technology choices. As of late, cryptocurrencies have garnered notoriety for excessive energy usage, with the spotlight on Proof of Work (PoW), an algorithm by which a decentralized set of participants can determine whether a transaction is valid. You may not be aware that PoW is only one option for consensus protocols, but there are others. Many projects are innovating in the field of consensus technology to produce a fast, energy-efficient, open-membership model to support payments worldwide. MobileCoin uses Federated Byzantine Agreement (FBA), an algorithm to achieve these properties with far fewer computers and processing cycles than other cryptocurrencies. Our consensus implementation delivers digital cash for your mobile device, without unnecessary consumption, so you can send green without worrying whether you are green.

Bitcoin Burns through Thailand’s Annual Energy Consumption and Creates Massive Noise Pollution

Most cryptocurrency activity takes place on blockchains that require large amounts of energy to store and validate transactions. This is due to cryptocurrency mining, where participating in validating transactions is rewarded, but at the cost of many CPU cycles as part of the “cost of participation,” or the “work.” This is not only energy-intensive but deafening. The noise pollution from Bitcoin mining farms can sound like a jet engine idling at an airport. Such is the case in Limestone, a small town in the Appalachian Mountains, where a new Bitcoin plant was built last year. The massive fans required to cool the computers produce constant sound pollution, a bane to residents and wildlife. Beyond the local impact of each mining farm, the energy waste is unsustainable, especially as cryptocurrency continues to gain adoption—if the current energy consumption trends of Bitcoin and other PoW coins continue, then those blockchains (with Bitcoin contributing more than ⅔ of the energy expenditure) will burn through an estimated 300+ terawatt-hours of energy this year—comparable to the rate of Thailand’s annual consumption, according to Digiconomist.

FBA Consensus Model Versus Proof of Work

At MobileCoin, we’ve left the work-intensive cryptocurrency miners behind in favor of FBA. FBA relies on a “trust graph” model to address unnecessary energy consumption while delivering added benefits such as low-latency, high-throughput transactions. The consensus mechanism (that is, how the servers decide on what data to append to the blockchain), occurs after a sufficient subset of network participants, called the “quorum threshold,” agrees that the outputs being sent from one person to another are legitimate, thereby coming to “consensus” on the next valid block. 

Instead of consuming the amount of energy that Thailand consumes in a year, MobileCoin’s power usage equates to the same energy used to power a few households. When compared with the myriad consensus algorithms available to blockchain projects, FBA ranks as one of the most energy-efficient choices, while also delivering speedy transactions and an open membership model. 

FBA addresses more than just the energy efficiency problems inherent to the Proof of Work model. Mining can lead to behavior on behalf of the node operators that externalizes the cost of the cryptocurrency’s incentive structure to the users and the planet. The cost externalization is somewhat similar to the way people who pay cash for goods and services are ultimately subsidizing credit card rewards programs due to the way the credit card fee is passed on from the merchant to the consumer via higher prices. In PoW, the block reward has to be sufficient when amortized over the likelihood of winning the block reward to offset the cost of electricity to operate a miner. This cost is passed on to the user in the form of high fees per transaction.

In addition, Miner Extracted Value (MEV) is a practice where miners exploit the malleable execution ordering of transactions to “front-run” and obtain price favorability in their own transaction activity. Mining, too, encourages prospective node operators to participate in the block award lottery, rather than maintaining a balance between decentralization and consumptive CPU treadmilling. In FBA, there is no block reward, and the transactions have a deterministic lexicographic ordering that deters exploitation and front-running.

Compared to the tens of thousands of servers used by Bitcoin, MobileCoin uses fewer than a hundred servers. Our consensus validator nodes are mostly idle by design—they only wake up when there is work to do (i.e. a user proposed a transaction), rather than requiring unnecessary work for a speculative reward.

MobileCoin’s Focus on Reduced Transaction Time Also Saves Energy

To serve users as a payments solution, we knew we had to deliver two key features: transactions that cleared within seconds, and mobile-first functionality. The latter is often referred to as “mobile custody” or “self custody,” meaning your private keys (and therefore access to your funds) are isolated to your device. This feature combo is surprisingly hard to deliver with most blockchain technology, and the industry seemed to take the stance that cryptocurrency as a payments solution was unfeasible, turning attention instead to NFTs and DeFi. At MobileCoin, we remained heads-down and laser-focused on the global payments dream, and we did it, raising the bar on what is possible with our technology given the constraints for a payments use case.  

Blockchain scalability is a huge area of research, and we take a novel approach. For a detailed breakdown, see our ELI5 explainer on Fog. What’s important in the context of sustainability is how our scalability solution adheres to the ethos of less work being more sustainable. We leverage an oblivious RAM (ORAM) data structure that supports hundreds of thousands of requests per second while keeping your data in your control, so the service operator is “oblivious” to it. Storing the ORAM data structures inside Intel’s Software Guard Extensions (SGX) secure enclaves enables us to incorporate hardware-accelerated encryption, which ultimately reduces running costs, and saves precious energy. In addition, we leverage advanced vector extension (AVX2) instructions in Intel’s chips to speed up operations four times over. 

If we look at our cryptographic primitives, we can see how even our choices here contribute to a lighter compute load. We chose Elliptic Curve Cryptography (ECC) over the Rivest-Shamir-Adleman (RSA) algorithm to perform cryptographic operations. Because ECC is a much more efficient algorithm than RSA, it achieves the same level of encryption, using significantly smaller key sizes. Smaller keys require less “computing power,” while offering more efficient options on resource-constrained devices. Further, we use the Ristretto Group, which is a prime order group over the Ed25519 elliptic curve and is known for its constant-time prowess and fast implementation.

Our Hosting Providers Also Focus on Environmental Commitments

We are not alone in prioritizing the health of our planet alongside computing power. Our node operators and hosting providers share this key value and address the urgency of climate change through a commitment to energy-efficient deployments and 100% renewable energy targets, alongside reliable uptime and high-performance connectivity. By partnering with like-minded organizations, we are advancing environmental policies to significantly reduce carbon footprints through lower costs and energy expenditure.

So, on this Earth Day, think about the cryptocurrency you want to use. Slow transactions that expend a lot of energy, or fast transactions on your smartphone that save our planet? The latest messaging app to introduce MobileCoin cryptocurrency is Signal.

For more information on how to use MOB on your smartphone, check out the beta version of the MobileCoin app: https://mobilecoin.com/beta

By Sara Drakeley
04/20/2022