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Jim Siwek

Jim Siwek

3 years ago

In 2022, can a lone developer be able to successfully establish a SaaS product?

More on Entrepreneurship/Creators

Jared Heyman

Jared Heyman

2 years ago

The survival and demise of Y Combinator startups

I've written a lot about Y Combinator's success, but as any startup founder or investor knows, many startups fail.

Rebel Fund invests in the top 5-10% of new Y Combinator startups each year, so we focus on identifying and supporting the most promising technology startups in our ecosystem. Given the power law dynamic and asymmetric risk/return profile of venture capital, we worry more about our successes than our failures. Since the latter still counts, this essay will focus on the proportion of YC startups that fail.

Since YC's launch in 2005, the figure below shows the percentage of active, inactive, and public/acquired YC startups by batch.

As more startups finish, the blue bars (active) decrease significantly. By 12 years, 88% of startups have closed or exited. Only 7% of startups reach resolution each year.

YC startups by status after 12 years:

Half the startups have failed, over one-third have exited, and the rest are still operating.

In venture investing, it's said that failed investments show up before successful ones. This is true for YC startups, but only in their early years.

Below, we only present resolved companies from the first chart. Some companies fail soon after establishment, but after a few years, the inactive vs. public/acquired ratio stabilizes around 55:45. After a few years, a YC firm is roughly as likely to quit as fail, which is better than I imagined.

I prepared this post because Rebel investors regularly question me about YC startup failure rates and how long it takes for them to exit or shut down.

Early-stage venture investors can overlook it because 100x investments matter more than 0x investments.

YC founders can ignore it because it shouldn't matter if many of their peers succeed or fail ;)

Victoria Kurichenko

Victoria Kurichenko

3 years ago

Here's what happened after I launched my second product on Gumroad.

One-hour ebook sales, affiliate relationships, and more.

Image credit: Karolina Grabovska. The image was edited in Canva

If you follow me, you may know I started a new ebook in August 2022.

Despite publishing on this platform, my website, and Quora, I'm not a writer.

My writing speed is slow, 2,000 words a day, and I struggle to communicate cohesively.

In April 2022, I wrote a successful guide on How to Write Google-Friendly Blog Posts.

I had no email list or social media presence. I've made $1,600+ selling ebooks.

Evidence:

My ebook sales on Gumroad

My first digital offering isn't a book.

It's an actionable guide with my tried-and-true process for writing Google-friendly content.

I'm not bragging.

Established authors like Tim Denning make more from my ebook sales with one newsletter.

This experience taught me writing isn't a privilege.

Writing a book and making money online doesn't require expertise.

Many don't consult experts. They want someone approachable.

Two years passed before I realized my own limits.

I have a brain, two hands, and Internet to spread my message.

I wrote and published a second ebook after the first's success.

On Gumroad, I released my second digital product.

Here's my complete Gumroad evaluation.

Gumroad is a marketplace for content providers to develop and sell sales pages.

Gumroad handles payments and client requests. It's helpful when someone sends a bogus payment receipt requesting an ebook (actual story!).

You'll forget administrative concerns after your first ebook sale.

After my first ebook sale, I did this: I made additional cash!

After every sale, I tell myself, "I built a new semi-passive revenue source."

This thinking shift helps me become less busy while increasing my income and quality of life.

Besides helping others, folks sell evergreen digital things to earn passive money.

It's in my second ebook.

I explain how I built and sold 50+ copies of my SEO writing ebook without being an influencer.

I show how anyone can sell ebooks on Gumroad and automate their sales process.

This is my ebook.

My second ebook on Gumroad

After publicizing the ebook release, I sold three copies within an hour.

Wow, or meh?

I don’t know.

The answer is different for everyone.

These three sales came from a small email list of 40 motivated fans waiting for my ebook release.

I had bigger plans.

I'll market my ebook on Medium, my website, Quora, and email.

I'm testing affiliate partnerships this time.

One of my ebook buyers is now promoting it for 40% commission.

Become my affiliate if you think your readers would like my ebook.

My ebook is a few days old, but I'm interested to see where it goes.

My SEO writing book started without an email list, affiliates, or 4,000 website visitors. I've made four figures.

I'm slowly expanding my communication avenues to have more impact.

Even a small project can open doors you never knew existed.

So began my writing career.

In summary

If you dare, every concept can become a profitable trip.

Before, I couldn't conceive of creating an ebook.

How to Sell eBooks on Gumroad is my second digital product.

Marketing and writing taught me that anything can be sold online.

Maddie Wang

Maddie Wang

3 years ago

Easiest and fastest way to test your startup idea!

Here's the fastest way to validate company concepts.

I squandered a year after dropping out of Stanford designing a product nobody wanted.

But today, I’m at 100k!

Differences:

I was designing a consumer product when I dropped out.

I coded MVP, got 1k users, and got YC interview.

Nice, huh?

WRONG!

Still coding and getting users 12 months later

WOULD PEOPLE PAY FOR IT? was the riskiest assumption I hadn't tested.

When asked why I didn't verify payment, I said,

Not-ready products. Now, nobody cares. The website needs work. Include this. Increase usage…

I feared people would say no.

After 1 year of pushing it off, my team told me they were really worried about the Business Model. Then I asked my audience if they'd buy my product.

So?

No, overwhelmingly.

I felt like I wasted a year building a product no one would buy.

Founders Cafe was the opposite.

Before building anything, I requested payment.

40 founders were interviewed.

Then we emailed Stanford, YC, and other top founders, asking them to join our community.

BOOM! 10/12 paid!

Without building anything, in 1 day I validated my startup's riskiest assumption. NOT 1 year.

Asking people to pay is one of the scariest things.

I understand.

I asked Stanford queer women to pay before joining my gay sorority.

I was afraid I'd turn them off or no one would pay.

Gay women, like those founders, were in such excruciating pain that they were willing to pay me upfront to help.

You can ask for payment (before you build) to see if people have the burning pain. Then they'll pay!

Examples from Founders Cafe members:

😮 Using a fake landing page, a college dropout tested a product. Paying! He built it and made $3m!

😮 YC solo founder faked a Powerpoint demo. 5 Enterprise paid LOIs. $1.5m raised, built, and in YC!

😮 A Harvard founder can convert Figma to React. 1 day, 10 customers. Built a tool to automate Figma -> React after manually fulfilling requests. 1m+

Bad example:

😭 Stanford Dropout Spends 1 Year Building Product Without Payment Validation

Some people build for a year and then get paying customers.

What I'm sharing is my experience and what Founders Cafe members have told me about validating startup ideas.

Don't waste a year like I did.

After my first startup failed, I planned to re-enroll at Stanford/work at Facebook.

After people paid, I quit for good.

I've hit $100k!

Hope this inspires you to request upfront payment! It'll change your life

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Guillaume Dumortier

Guillaume Dumortier

2 years ago

Mastering the Art of Rhetoric: A Guide to Rhetorical Devices in Successful Headlines and Titles

Unleash the power of persuasion and captivate your audience with compelling headlines.

As the old adage goes, "You never get a second chance to make a first impression."

In the world of content creation and social ads, headlines and titles play a critical role in making that first impression.

A well-crafted headline can make the difference between an article being read or ignored, a video being clicked on or bypassed, or a product being purchased or passed over.

To make an impact with your headlines, mastering the art of rhetoric is essential. In this post, we'll explore various rhetorical devices and techniques that can help you create headlines that captivate your audience and drive engagement.


tl;dr : Headline Magician will help you craft the ultimate headline titles powered by rhetoric devices

No alt text provided for this image

Example with a high-end luxury organic zero-waste skincare brand


✍️ The Power of Alliteration

Alliteration is the repetition of the same consonant sound at the beginning of words in close proximity. This rhetorical device lends itself well to headlines, as it creates a memorable, rhythmic quality that can catch a reader's attention.

By using alliteration, you can make your headlines more engaging and easier to remember.

Examples:

"Crafting Compelling Content: A Comprehensive Course"

"Mastering the Art of Memorable Marketing"


🔁 The Appeal of Anaphora

Anaphora is the repetition of a word or phrase at the beginning of successive clauses. This rhetorical device emphasizes a particular idea or theme, making it more memorable and persuasive.

In headlines, anaphora can be used to create a sense of unity and coherence, which can draw readers in and pique their interest.

Examples:

"Create, Curate, Captivate: Your Guide to Social Media Success"

"Innovation, Inspiration, and Insight: The Future of AI"


🔄 The Intrigue of Inversion

Inversion is a rhetorical device where the normal order of words is reversed, often to create an emphasis or achieve a specific effect.

In headlines, inversion can generate curiosity and surprise, compelling readers to explore further.

Examples:

"Beneath the Surface: A Deep Dive into Ocean Conservation"

"Beyond the Stars: The Quest for Extraterrestrial Life"


⚖️ The Persuasive Power of Parallelism

Parallelism is a rhetorical device that involves using similar grammatical structures or patterns to create a sense of balance and symmetry.

In headlines, parallelism can make your message more memorable and impactful, as it creates a pleasing rhythm and flow that can resonate with readers.

Examples:

"Eat Well, Live Well, Be Well: The Ultimate Guide to Wellness"

"Learn, Lead, and Launch: A Blueprint for Entrepreneurial Success"


⏭️ The Emphasis of Ellipsis

Ellipsis is the omission of words, typically indicated by three periods (...), which suggests that there is more to the story.

In headlines, ellipses can create a sense of mystery and intrigue, enticing readers to click and discover what lies behind the headline.

Examples:

"The Secret to Success... Revealed"

"Unlocking the Power of Your Mind... A Step-by-Step Guide"


🎭 The Drama of Hyperbole

Hyperbole is a rhetorical device that involves exaggeration for emphasis or effect.

In headlines, hyperbole can grab the reader's attention by making bold, provocative claims that stand out from the competition. Be cautious with hyperbole, however, as overuse or excessive exaggeration can damage your credibility.

Examples:

"The Ultimate Guide to Mastering Any Skill in Record Time"

"Discover the Revolutionary Technique That Will Transform Your Life"


❓The Curiosity of Questions

Posing questions in your headlines can be an effective way to pique the reader's curiosity and encourage engagement.

Questions compel the reader to seek answers, making them more likely to click on your content. Additionally, questions can create a sense of connection between the content creator and the audience, fostering a sense of dialogue and discussion.

Examples:

"Are You Making These Common Mistakes in Your Marketing Strategy?"

"What's the Secret to Unlocking Your Creative Potential?"


💥 The Impact of Imperatives

Imperatives are commands or instructions that urge the reader to take action. By using imperatives in your headlines, you can create a sense of urgency and importance, making your content more compelling and actionable.

Examples:

"Master Your Time Management Skills Today"

"Transform Your Business with These Innovative Strategies"


💢 The Emotion of Exclamations

Exclamations are powerful rhetorical devices that can evoke strong emotions and convey a sense of excitement or urgency.

Including exclamations in your headlines can make them more attention-grabbing and shareable, increasing the chances of your content being read and circulated.

Examples:

"Unlock Your True Potential: Find Your Passion and Thrive!"

"Experience the Adventure of a Lifetime: Travel the World on a Budget!"


🎀 The Effectiveness of Euphemisms

Euphemisms are polite or indirect expressions used in place of harsher, more direct language.

In headlines, euphemisms can make your message more appealing and relatable, helping to soften potentially controversial or sensitive topics.

Examples:

"Navigating the Challenges of Modern Parenting"

"Redefining Success in a Fast-Paced World"


⚡Antithesis: The Power of Opposites

Antithesis involves placing two opposite words side-by-side, emphasizing their contrasts. This device can create a sense of tension and intrigue in headlines.

Examples:

"Once a day. Every day"

"Soft on skin. Kill germs"

"Mega power. Mini size."

To utilize antithesis, identify two opposing concepts related to your content and present them in a balanced manner.


🎨 Scesis Onomaton: The Art of Verbless Copy

Scesis onomaton is a rhetorical device that involves writing verbless copy, which quickens the pace and adds emphasis.

Example:

"7 days. 7 dollars. Full access."

To use scesis onomaton, remove verbs and focus on the essential elements of your headline.


🌟 Polyptoton: The Charm of Shared Roots

Polyptoton is the repeated use of words that share the same root, bewitching words into memorable phrases.

Examples:

"Real bread isn't made in factories. It's baked in bakeries"

"Lose your knack for losing things."

To employ polyptoton, identify words with shared roots that are relevant to your content.


✨ Asyndeton: The Elegance of Omission

Asyndeton involves the intentional omission of conjunctions, adding crispness, conviction, and elegance to your headlines.

Examples:

"You, Me, Sushi?"

"All the latte art, none of the environmental impact."

To use asyndeton, eliminate conjunctions and focus on the core message of your headline.


🔮 Tricolon: The Magic of Threes

Tricolon is a rhetorical device that uses the power of three, creating memorable and impactful headlines.

Examples:

"Show it, say it, send it"

"Eat Well, Live Well, Be Well."

To use tricolon, craft a headline with three key elements that emphasize your content's main message.


🔔 Epistrophe: The Chime of Repetition

Epistrophe involves the repetition of words or phrases at the end of successive clauses, adding a chime to your headlines.

Examples:

"Catch it. Bin it. Kill it."

"Joint friendly. Climate friendly. Family friendly."

To employ epistrophe, repeat a key phrase or word at the end of each clause.

Julie Plavnik

Julie Plavnik

3 years ago

How to Become a Crypto Broker [Complying and Making Money]

Three options exist. The third one is the quickest and most fruitful.

How To Become a Cryptocurrency Broker?

You've mastered crypto trading and want to become a broker.

So you may wonder: Where to begin?

If so, keep reading.

Today I'll compare three different approaches to becoming a cryptocurrency trader.

What are cryptocurrency brokers, and how do they vary from stockbrokers?

A stockbroker implements clients' market orders (retail or institutional ones).

Brokerage firms are regulated, insured, and subject to regulatory monitoring.

Stockbrokers are required between buyers and sellers. They can't trade without a broker. To trade, a trader must open a broker account and deposit money. When a trader shops, he tells his broker what orders to place.

Crypto brokerage is trade intermediation with cryptocurrency.

In crypto trading, however, brokers are optional.

Crypto exchanges offer direct transactions. Open an exchange account (no broker needed) and make a deposit.

Question:

Since crypto allows DIY trading, why use a broker?

Let's compare cryptocurrency exchanges vs. brokers.

Broker versus cryptocurrency exchange

Most existing crypto exchanges are basically brokers.

Examine their primary services:

  • connecting purchasers and suppliers

  • having custody of clients' money (with the exception of decentralized cryptocurrency exchanges),

  • clearance of transactions.

Brokerage is comparable, don't you think?

There are exceptions. I mean a few large crypto exchanges that follow the stock exchange paradigm. They outsource brokerage, custody, and clearing operations. Classic exchange setups are rare in today's bitcoin industry.

Back to our favorite “standard” crypto exchanges. All-in-one exchanges and brokers. And usually, they operate under a broker or a broker-dealer license, save for the exchanges registered somewhere in a free-trade offshore paradise. Those don’t bother with any licensing.

What’s the sense of having two brokers at a time?

Better liquidity and trading convenience.

The crypto business is compartmentalized.

We have CEXs, DEXs, hybrid exchanges, and semi-exchanges (those that aggregate liquidity but do not execute orders on their sides). All have unique regulations and act as sovereign states.

There are about 18k coins and hundreds of blockchain protocols, most of which are heterogeneous (i.e., different in design and not interoperable).

A trader must register many accounts on different exchanges, deposit funds, and manage them all concurrently to access global crypto liquidity.

It’s extremely inconvenient.

Crypto liquidity fragmentation is the largest obstacle and bottleneck blocking crypto from mass adoption.

Crypto brokers help clients solve this challenge by providing one-gate access to deep and diverse crypto liquidity from numerous exchanges and suppliers. Professionals and institutions need it.

Another killer feature of a brokerage may be allowing clients to trade crypto with fiat funds exclusively, without fiat/crypto conversion. It is essential for professional and institutional traders.

Who may work as a cryptocurrency broker?

Apparently, not anyone. Brokerage requires high-powered specialists because it involves other people's money.

Here's the essentials:

  • excellent knowledge, skills, and years of trading experience

  • high-quality, quick, and secure infrastructure

  • highly developed team

  • outstanding trading capital

  • High-ROI network: long-standing, trustworthy connections with customers, exchanges, liquidity providers, payment gates, and similar entities

  • outstanding marketing and commercial development skills.

What about a license for a cryptocurrency broker? Is it necessary?

Complex question.

If you plan to play in white-glove jurisdictions, you may need a license. For example, in the US, as a “money transmitter” or as a CASSP (crypto asset secondary services provider) in Australia.

Even in these jurisdictions, there are no clear, holistic crypto brokerage and licensing policies.

Your lawyer will help you decide if your crypto brokerage needs a license.

Getting a license isn't quick. Two years of patience are needed.

How can you turn into a cryptocurrency broker?

Finally, we got there! 🎉

Three actionable ways exist:

  1. To kickstart a regulated stand-alone crypto broker

  2. To get a crypto broker franchise, and

  3. To become a liquidity network broker.

Let's examine each.

1. Opening a regulated cryptocurrency broker

It's difficult. Especially If you're targeting first-world users.

You must comply with many regulatory, technical, financial, HR, and reporting obligations to keep your organization running. Some are mentioned above.

The licensing process depends on the products you want to offer (spots or derivatives) and the geographic areas you plan to service. There are no general rules for that.

In an overgeneralized way, here are the boxes you will have to check:

  • capital availability (usually a large amount of capital c is required)

  • You will have to move some of your team members to the nation providing the license in order to establish an office presence there.

  • the core team with the necessary professional training (especially applies to CEO, Head of Trading, Assistant to Head of Trading, etc.)

  • insurance

  • infrastructure that is trustworthy and secure

  • adopted proper AML/KYC/financial monitoring policies, etc.

Assuming you passed, what's next?

I bet it won’t be mind-blowing for you that the license is just a part of the deal. It won't attract clients or revenue.

To bring in high-dollar clientele, you must be a killer marketer and seller. It's not easy to convince people to give you money.

You'll need to be a great business developer to form successful, long-term agreements with exchanges (ideally for no fees), liquidity providers, banks, payment gates, etc. Persuade clients.

It's a tough job, isn't it?

I expect a Quora-type question here:

Can I start an unlicensed crypto broker?

Well, there is always a workaround with crypto!

You can register your broker in a free-trade zone like Seychelles to avoid US and other markets with strong watchdogs.

This is neither wise nor sustainable.

First, such experiments are illegal.

Second, you'll have trouble attracting clients and strategic partners.

A license equals trust. That’s it.

Even a pseudo-license from Mauritius matters.

Here are this method's benefits and downsides.

Cons first.

  • As you navigate this difficult and expensive legal process, you run the risk of missing out on business prospects. It's quite simple to become excellent compliance yet unable to work. Because your competitors are already courting potential customers while you are focusing all of your effort on paperwork.

  • Only God knows how long it will take you to pass the break-even point when everything with the license has been completed.

  • It is a money-burning business, especially in the beginning when the majority of your expenses will go toward marketing, sales, and maintaining license requirements. Make sure you have the fortitude and resources necessary to face such a difficult challenge.

Pros

  • It may eventually develop into a tool for making money. Because big guys who are professionals at trading require a white-glove regulated brokerage. You have every possibility if you work hard in the areas of sales, marketing, business development, and wealth. Simply put, everything must align.

Launching a regulated crypto broker is analogous to launching a crypto exchange. It's ROUGH. Sure you can take it?

2. Franchise for Crypto Broker (Crypto Sub-Brokerage)

A broker franchise is easier and faster than becoming a regulated crypto broker. Not a traditional brokerage.

A broker franchisee, often termed a sub-broker, joins with a broker (a franchisor) to bring them new clients. Sub-brokers market a broker's products and services to clients.

Sub-brokers are the middlemen between a broker and an investor.

Why is sub-brokering easier?

  • less demanding qualifications and legal complexity. All you need to do is keep a few certificates on hand (each time depends on the jurisdiction).

  • No significant investment is required

  • there is no demand that you be a trading member of an exchange, etc.

As a sub-broker, you can do identical duties without as many rights and certifications.

What about the crypto broker franchise?

Sub-brokers aren't common in crypto.

In most existing examples (PayBito, PCEX, etc.), franchises are offered by crypto exchanges, not brokers. Though we remember that crypto exchanges are, in fact, brokers, do we?

Similarly:

  • For a commission, a franchiser crypto broker receives new leads from a crypto sub-broker.

See above for why enrolling is easy.

Finding clients is difficult. Most crypto traders prefer to buy-sell on their own or through brokers over sub-broker franchises.

3. Broker of the Crypto Trading Network (or a Network Broker)

It's the greatest approach to execute crypto brokerage, based on effort/return.

Network broker isn't an established word. I wrote it for clarity.

Remember how we called crypto liquidity fragmentation the current crypto finance paradigm's main bottleneck?

Where there's a challenge, there's progress.

Several well-funded projects are aiming to fix crypto liquidity fragmentation. Instead of launching another crypto exchange with siloed trading, the greatest minds create trading networks that aggregate crypto liquidity from desynchronized sources and enable quick, safe, and affordable cross-blockchain transactions. Each project offers a distinct option for users.

Crypto liquidity implies:

  • One-account access to cryptocurrency liquidity pooled from network participants' exchanges and other liquidity sources

  • compiled price feeds

  • Cross-chain transactions that are quick and inexpensive, even for HFTs

  • link between participants of all kinds, and

  • interoperability among diverse blockchains

Fast, diversified, and cheap global crypto trading from one account.

How does a trading network help cryptocurrency brokers?

I’ll explain it, taking Yellow Network as an example.

Yellow provides decentralized Layer-3 peer-to-peer trading.

  • trade across chains globally with real-time settlement and

  • Between cryptocurrency exchanges, brokers, trading companies, and other sorts of network members, there is communication and the exchange of financial information.

Have you ever heard about ECN (electronic communication network)? If not, it's an automated system that automatically matches buy and sell orders. Yellow is a decentralized digital asset ECN.

Brokers can:

  • Start trading right now without having to meet stringent requirements; all you need to do is integrate with Yellow Protocol and successfully complete some KYC verification.

  • Access global aggregated crypto liquidity through a single point.

  • B2B (Broker to Broker) liquidity channels that provide peer liquidity from other brokers. Orders from the other broker will appear in the order book of a broker who is peering with another broker on the market. It will enable a broker to broaden his offer and raise the total amount of liquidity that is available to his clients.

  • Select a custodian or use non-custodial practices.

Comparing network crypto brokerage to other types:

  • A licensed stand-alone brokerage business is much more difficult and time-consuming to launch than network brokerage, and

  • Network brokerage, in contrast to crypto sub-brokerage, is scalable, independent, and offers limitless possibilities for revenue generation.

Yellow Network Whitepaper. has more details on how to start a brokerage business and what rewards you'll obtain.

Final thoughts

There are three ways to become a cryptocurrency broker, including the non-conventional liquidity network brokerage. The last option appears time/cost-effective.

Crypto brokerage isn't crowded yet. Act quickly to find your right place in this market.

Choose the way that works for you best and see you in crypto trading.

Discover Web3 & DeFi with Yellow Network!

Yellow, powered by Openware, is developing a cross-chain P2P liquidity aggregator to unite the crypto sector and provide global remittance services that aid people.

Join the Yellow Community and plunge into this decade's biggest product-oriented crypto project.

  • Observe Yellow Twitter

  • Enroll in Yellow Telegram

  • Visit Yellow Discord.

  • On Hacker Noon, look us up.

Yellow Network will expose development, technology, developer tools, crypto brokerage nodes software, and community liquidity mining.

Vitalik

Vitalik

3 years ago

An approximate introduction to how zk-SNARKs are possible (part 1)

You can make a proof for the statement "I know a secret number such that if you take the word ‘cow', add the number to the end, and SHA256 hash it 100 million times, the output starts with 0x57d00485aa". The verifier can verify the proof far more quickly than it would take for them to run 100 million hashes themselves, and the proof would also not reveal what the secret number is.

In the context of blockchains, this has 2 very powerful applications: Perhaps the most powerful cryptographic technology to come out of the last decade is general-purpose succinct zero knowledge proofs, usually called zk-SNARKs ("zero knowledge succinct arguments of knowledge"). A zk-SNARK allows you to generate a proof that some computation has some particular output, in such a way that the proof can be verified extremely quickly even if the underlying computation takes a very long time to run. The "ZK" part adds an additional feature: the proof can keep some of the inputs to the computation hidden.

You can make a proof for the statement "I know a secret number such that if you take the word ‘cow', add the number to the end, and SHA256 hash it 100 million times, the output starts with 0x57d00485aa". The verifier can verify the proof far more quickly than it would take for them to run 100 million hashes themselves, and the proof would also not reveal what the secret number is.

In the context of blockchains, this has two very powerful applications:

  1. Scalability: if a block takes a long time to verify, one person can verify it and generate a proof, and everyone else can just quickly verify the proof instead
  2. Privacy: you can prove that you have the right to transfer some asset (you received it, and you didn't already transfer it) without revealing the link to which asset you received. This ensures security without unduly leaking information about who is transacting with whom to the public.

But zk-SNARKs are quite complex; indeed, as recently as in 2014-17 they were still frequently called "moon math". The good news is that since then, the protocols have become simpler and our understanding of them has become much better. This post will try to explain how ZK-SNARKs work, in a way that should be understandable to someone with a medium level of understanding of mathematics.

Why ZK-SNARKs "should" be hard

Let us take the example that we started with: we have a number (we can encode "cow" followed by the secret input as an integer), we take the SHA256 hash of that number, then we do that again another 99,999,999 times, we get the output, and we check what its starting digits are. This is a huge computation.

A "succinct" proof is one where both the size of the proof and the time required to verify it grow much more slowly than the computation to be verified. If we want a "succinct" proof, we cannot require the verifier to do some work per round of hashing (because then the verification time would be proportional to the computation). Instead, the verifier must somehow check the whole computation without peeking into each individual piece of the computation.

One natural technique is random sampling: how about we just have the verifier peek into the computation in 500 different places, check that those parts are correct, and if all 500 checks pass then assume that the rest of the computation must with high probability be fine, too?

Such a procedure could even be turned into a non-interactive proof using the Fiat-Shamir heuristic: the prover computes a Merkle root of the computation, uses the Merkle root to pseudorandomly choose 500 indices, and provides the 500 corresponding Merkle branches of the data. The key idea is that the prover does not know which branches they will need to reveal until they have already "committed to" the data. If a malicious prover tries to fudge the data after learning which indices are going to be checked, that would change the Merkle root, which would result in a new set of random indices, which would require fudging the data again... trapping the malicious prover in an endless cycle.

But unfortunately there is a fatal flaw in naively applying random sampling to spot-check a computation in this way: computation is inherently fragile. If a malicious prover flips one bit somewhere in the middle of a computation, they can make it give a completely different result, and a random sampling verifier would almost never find out.


It only takes one deliberately inserted error, that a random check would almost never catch, to make a computation give a completely incorrect result.

If tasked with the problem of coming up with a zk-SNARK protocol, many people would make their way to this point and then get stuck and give up. How can a verifier possibly check every single piece of the computation, without looking at each piece of the computation individually? There is a clever solution.

see part 2