How I made $160,000 from non-fiction books
I've sold over 40,000 non-fiction books on Amazon and made over $160,000 in six years while writing on the side.
I have a full-time job and three young sons; I can't spend 40 hours a week writing. This article describes my journey.
I write mainly tech books:
Thanks to my readers, many wrote positive evaluations. Several are bestsellers.
A few have been adopted by universities as textbooks:
My books' passive income allows me more time with my family.
Knowing I could quit my job and write full time gave me more confidence. And I find purpose in my work (i am in christian ministry).
I'm always eager to write. When work is a dread or something bad happens, writing gives me energy. Writing isn't scary. In fact, I can’t stop myself from writing!
Writing has also established my tech authority. Universities use my books, as I've said. Traditional publishers have asked me to write books.
These mindsets helped me become a successful nonfiction author:
1. You don’t have to be an Authority
Yes, I have computer science experience. But I'm no expert on my topics. Before authoring "Beginning Node.js, Express & MongoDB," my most profitable book, I had no experience with those topics. Node was a new server-side technology for me. Would that stop me from writing a book? It can. I liked learning a new technology. So I read the top three Node books, took the top online courses, and put them into my own book (which makes me know more than 90 percent of people already).
I didn't have to worry about using too much jargon because I was learning as I wrote. An expert forgets a beginner's hardship.
"The fellow learner can aid more than the master since he knows less," says C.S. Lewis. The problem he must explain is recent. The expert has forgotten.”
2. Solve a micro-problem (Niching down)
I didn't set out to write a definitive handbook. I found a market with several challenges and wrote one book. Ex:
- Instead of web development, what about web development using Angular?
- Instead of Blockchain, what about Blockchain using Solidity and React?
- Instead of cooking recipes, how about a recipe for a specific kind of diet?
- Instead of Learning math, what about Learning Singapore Math?
3. Piggy Backing Trends
The above topics may still be a competitive market. E.g. Angular, React. To stand out, include the latest technologies or trends in your book. Learn iOS 15 instead of iOS programming. Instead of personal finance, what about personal finance with NFTs.
Even though you're a newbie author, your topic is well-known.
4. Publish short books
My books are known for being direct. Many people like this:
Your reader will appreciate you cutting out the fluff and getting to the good stuff. A reader can finish and review your book.
Second, short books are easier to write. Instead of creating a 500-page book for $50 (which few will buy), write a 100-page book that answers a subset of the problem and sell it for less. (You make less, but that's another subject). At least it got published instead of languishing. Less time spent creating a book means less time wasted if it fails. Write a small-bets book portfolio like Daniel Vassallo!
Third, it's $2.99-$9.99 on Amazon (gets 70 percent royalties for ebooks). Anything less receives 35% royalties. $9.99 books have 20,000–30,000 words. If you write more and charge more over $9.99, you get 35% royalties. Why not make it a $9.99 book?
(This is the ebook version.) Paperbacks cost more. Higher royalties allow for higher prices.
5. Validate book idea
Amazon will tell you if your book concept, title, and related phrases are popular. See? Check its best-sellers list.
150,000 is preferable. It sells 2–3 copies daily. Consider your rivals. Profitable niches have high demand and low competition.
Don't be afraid of competitive niches. First, it shows high demand. Secondly, what are the ways you can undercut the completion? Better book? Or cheaper option? There was lots of competition in my NodeJS book's area. None received 4.5 stars or more. I wrote a NodeJS book. Today, it's a best-selling Node book.
What’s Next
So long. Part II follows. Meanwhile, I will continue to write more books!
Follow my journey on Twitter.
This post is a summary. Read full article here
More on Entrepreneurship/Creators

Davlin Knight
2 years ago
2 pitfalls to stay away from when launching a YouTube channel
You do not want to miss these
Stop! Stop it! Two things to avoid when starting a YouTube channel. Critical. Possible channel-killers Its future revenue.
I'll tell you now, so don't say "I wish I knew."
The Notorious Copyright Allegation
My YouTube channel received a copyright claim before I sold it. This claim was on a one-minute video I thought I'd changed enough to make mine, but the original owner disagreed.
It cost me thousands in ad revenue. Original owner got the profits.
Well, it wasn't your video, you say.
Touché.
I've learned. Sorta
I couldn't stop looking at the video's views. The video got 1,000,000 views without any revenue. I made 4 more similar videos.
If they didn't get copyrighted, I'd be rolling in dough.
You've spent a week editing and are uploading to YouTube. You're thrilled as you stand and stretch your back. You see the video just before publishing.
No way!
The red exclamation point on checks.
Copyright claim!
YouTube lets you publish, but you won't make money.
Sounds fair? Well, it is.
Copyright claims mean you stole someone's work. Song, image, or video clip.
We wouldn't want our content used for money.
The only problem with this is that almost everything belongs to someone else. I doubt some of the biggest creators are sitting down and making their music for their videos. That just seems really excessive when you could make a quick search on YouTube and download a song (I definitely don’t do this because that would be stealing).
So how do you defeat a copyright defense?
Even copyright-free songs on YouTube aren't guaranteed. Some copyrighted songs claim to be free.
Use YouTube's free music library or pay for a subscription to adobe stock, epidemic sound, or artlist.io.
Most of my videos have Nintendo music. Almost all game soundtracks are copyright-free and offer a variety of songs.
Restriction on age
Age restrictions are a must-avoid. A channel dies.
YouTube never suggests age-restricted videos.
Shadow banning means YouTube hides your content from subscribers and non-subscribers.
Keeping your channel family-friendly can help.
I hear you complaining that your channel isn't for kids. I agree. Not everyone has a clean mouth or creates content for minors.
YouTube has changed rapidly in recent years. Focusing on kids. Fewer big creators are using profanity or explicit content in videos. Not YouTube-worthy.
Youtube wants to be family-friendly. A family-friendly movie. It won't promote illegal content. Yes, it allows profanity.
Do I recommend avoiding no-no words in videos? Never. Okay. YouTube's policies are shaky. YouTube uses video content to determine ad suitability.
No joke. If you're serious about becoming a content creator, avoid profanity and inappropriate topics.
If your channel covers 18+ topics, like crime or commentary, censor as much as possible.
YouTube can be like walking on eggshells. You never know what is gonna upset the boss. So play it safe and try to avoid getting on their bad side.
Mr. Beast, Dream, Markplier, Faze Rug, and PewDewPie are popular creators. They maintain it family-friendly while entertaining fans.
You got this.

Desiree Peralta
3 years ago
Why Now Is Your Chance To Create A Millionaire Career
People don’t believe in influencers anymore; they need people like you.
Social media influencers have dominated for years. We've seen videos, images, and articles of *famous* individuals unwrapping, reviewing, and endorsing things.
This industry generates billions. This year, marketers spent $2.23 billion on Instagram, $1 million on Youtube, and $775 million on Tiktok. This marketing has helped start certain companies.
Influencers are dying, so ordinary people like us may take over this billion-dollar sector. Why?
Why influencers are perishing
Most influencers lie to their fans, especially on Instagram. Influencers' first purpose was to make their lives so flawless that others would want to buy their stuff.
In 2015, an Australian influencer with 600,000 followers went viral for revealing all her photos and everything she did to seem great before deleting her account.
“I dramatically edited the pictures, I manipulated the environements, and made my life look perfect in social media… I remember I obsessively checked the like count for a full week since uploading it, a selfie that now has close to 2,500 likes. It got 5 likes. This was when I was so hungry for social media validation … This was the reason why I quit social media: for me, personally, it consumed me. I wasn’t living in a 3D world.”
Influencers then lost credibility.
Influencers seem to live in a bubble, separate from us. Thanks to self-popularity love's and constant awareness campaigns, people find these people ridiculous.
Influencers are praised more for showing themselves as natural and common than for showing luxuries and lies.
Little by little, they are dying, making room for a new group to take advantage of this multi-million dollar business, which gives us (ordinary people) a big opportunity to grow on any content creation platform we want.
Why this is your chance to develop on any platform for creating content
In 2021, I wrote “Not everyone who talks about money is a Financial Advisor, be careful of who you take advice from,”. In it, I warned that not everyone with a large following is a reputable source of financial advice.
Other writers hated this post and said I was wrong.
People don't want Jeff Bezos or Elon Musk's counsel, they said. They prefer to hear about their neighbor's restroom problems or his closest friend's terrible business.
Real advice from regular folks.
And I found this was true when I returned to my independent YouTube channel and had more than 1000 followers after having abandoned it with fewer than 30 videos in 2021 since there were already many personal finance and travel channels and I thought mine wasn't special.
People appreciated my videos because I was a 20-something girl trying to make money online, and they believed my advice more than that of influencers with thousands of followers.
I think today is the greatest time to grow on any platform as an ordinary person. Normal individuals give honest recommendations about what works for them and look easier to make because they have the same options as us.
Nobody cares how a millionaire acquired a Lamborghini unless it's entertaining. Education works now. Real counsel from average people is replicable.
Many individuals don't appreciate how false influencers seem (unreal bodies and excessive surgery and retouching) since it makes them feel uneasy.
That's why body-positive advertisements have been so effective, but they've lost ground in places like Tiktok, where the audience wants more content from everyday people than influencers living amazing lives. More people will relate to your content if you appear genuine.
Last thoughts
Influencers are dwindling. People want more real people to give real advice and demonstrate an ordinary life.
People will enjoy anything you tell about your daily life as long as you provide value, and you can build a following rapidly if you're honest.
This is a millionaire industry that is getting more expensive and will go with what works, so stand out immediately.

Jenn Leach
3 years ago
In November, I made an effort to pitch 10 brands per day. Here's what I discovered.
I pitched 10 brands per workday for a total of 200.
How did I do?
It was difficult.
I've never pitched so much.
What did this challenge teach me?
the superiority of quality over quantity
When you need help, outsource
Don't disregard burnout in order to complete a challenge because it exists.
First, pitching brands for brand deals requires quality. Find firms that align with your brand to expose to your audience.
If you associate with any company, you'll lose audience loyalty. I didn't lose sight of that, but I couldn't resist finishing the task.
Outsourcing.
Delegating work to teammates is effective.
I wish I'd done it.
Three people can pitch 200 companies a month significantly faster than one.
One person does research, one to two do outreach, and one to two do follow-up and negotiating.
Simple.
In 2022, I'll outsource everything.
Burnout.
I felt this, so I slowed down at the end of the month.
Thanksgiving week in November was slow.
I was buying and decorating for Christmas. First time putting up outdoor holiday lights was fun.
Much was happening.
I'm not perfect.
I'm being honest.
The Outcomes
Less than 50 brands pitched.
Result: A deal with 3 brands.
I hoped for 4 brands with reaching out to 200 companies, so three with under 50 is wonderful.
That’s a 6% conversion rate!
Whoo-hoo!
I needed 2%.
Here's a screenshot from one of the deals I booked.
These companies fit my company well. Each campaign is different, but I've booked $2,450 in brand work with a couple of pending transactions for December and January.
$2,450 in brand work booked!
How did I do? You tell me.
Is this something you’d try yourself?
You might also like
Dmytro Spilka
2 years ago
Why NFTs Have a Bright Future Away from Collectible Art After Punks and Apes
After a crazy second half of 2021 and significant trade volumes into 2022, the market for NFT artworks like Bored Ape Yacht Club, CryptoPunks, and Pudgy Penguins has begun a sharp collapse as market downturns hit token values.
DappRadar data shows NFT monthly sales have fallen below $1 billion since June 2021. OpenSea, the world's largest NFT exchange, has seen sales volume decline 75% since May and is trading like July 2021.
Prices of popular non-fungible tokens have also decreased. Bored Ape Yacht Club (BAYC) has witnessed volume and sales drop 63% and 15%, respectively, in the past month.
BeInCrypto analysis shows market decline. May 2022 cryptocurrency marketplace volume was $4 billion, according to a news platform. This is a sharp drop from April's $7.18 billion.
OpenSea, a big marketplace, contributed $2.6 billion, while LooksRare, Magic Eden, and Solanart also contributed.
NFT markets are digital platforms for buying and selling tokens, similar stock trading platforms. Although some of the world's largest exchanges offer NFT wallets, most users store their NFTs on their favorite marketplaces.
In January 2022, overall NFT sales volume was $16.57 billion, with LooksRare contributing $11.1 billion. May 2022's volume was $12.57 less than January, a 75% drop, and June's is expected to be considerably smaller.
A World Based on Utility
Despite declines in NFT trading volumes, not all investors are negative on NFTs. Although there are uncertainties about the sustainability of NFT-based art collections, there are fewer reservations about utility-based tokens and their significance in technology's future.
In June, business CEO Christof Straub said NFTs may help artists monetize unreleased content, resuscitate catalogs, establish deeper fan connections, and make processes more efficient through technology.
We all know NFTs can't be JPEGs. Straub noted that NFT music rights can offer more equitable rewards to musicians.
Music NFTs are here to stay if they have real value, solve real problems, are trusted and lawful, and have fair and sustainable business models.
NFTs can transform numerous industries, including music. Market opinion is shifting towards tokens with more utility than the social media artworks we're used to seeing.
While the major NFT names remain dominant in terms of volume, new utility-based initiatives are emerging as top 20 collections.
Otherdeed, Sorare, and NBA Top Shot are NFT-based games that rank above Bored Ape Yacht Club and Cryptopunks.
Users can switch video NFTs of basketball players in NBA Top Shot. Similar efforts are emerging in the non-fungible landscape.
Sorare shows how NFTs can support a new way of playing fantasy football, where participants buy and swap trading cards to create a 5-player team that wins rewards based on real-life performances.
Sorare raised 579.7 million in one of Europe's largest Series B financing deals in September 2021. Recently, the platform revealed plans to expand into Major League Baseball.
Strong growth indications suggest a promising future for NFTs. The value of art-based collections like BAYC and CryptoPunks may be questioned as markets become diluted by new limited collections, but the potential for NFTs to become intrinsically linked to tangible utility like online gaming, music and art, and even corporate reward schemes shows the industry has a bright future.

Hudson Rennie
2 years ago
My Work at a $1.2 Billion Startup That Failed
Sometimes doing everything correctly isn't enough.
In 2020, I could fix my life.
After failing to start a business, I owed $40,000 and had no work.
A $1.2 billion startup on the cusp of going public pulled me up.
Ironically, it was getting ready for an epic fall — with the world watching.
Life sometimes helps. Without a base, even the strongest fall. A corporation that did everything right failed 3 months after going public.
First-row view.
Apple is the creator of Adore.
Out of respect, I've altered the company and employees' names in this account, despite their failure.
Although being a publicly traded company, it may become obvious.
We’ll call it “Adore” — a revolutionary concept in retail shopping.
Two Apple execs established Adore in 2014 with a focus on people-first purchasing.
Jon and Tim:
The concept for the stylish Apple retail locations you see today was developed by retail expert Jon Swanson, who collaborated closely with Steve Jobs.
Tim Cruiter is a graphic designer who produced the recognizable bouncing lamp video that appears at the start of every Pixar film.
The dynamic duo realized their vision.
“What if you could combine the convenience of online shopping with the confidence of the conventional brick-and-mortar store experience.”
Adore's mobile store concept combined traditional retail with online shopping.
Adore brought joy to 70+ cities and 4 countries over 7 years, including the US, Canada, and the UK.
Being employed on the ground floor, with world dominance and IPO on the horizon, was exciting.
I started as an Adore Expert.
I delivered cell phones, helped consumers set them up, and sold add-ons.
As the company grew, I became a Virtual Learning Facilitator and trained new employees across North America using Zoom.
In this capacity, I gained corporate insider knowledge. I worked with the creative team and Jon and Tim.
It's where I saw company foundation fissures. Despite appearances, investors were concerned.
The business strategy was ground-breaking.
Even after seeing my employee stocks fall from a home down payment to $0 (when Adore filed for bankruptcy), it's hard to pinpoint what went wrong.
Solid business model, well-executed.
Jon and Tim's chase for public funding ended in glory.
Here’s the business model in a nutshell:
Buying cell phones is cumbersome. You have two choices:
Online purchase: not knowing what plan you require or how to operate your device.
Enter a store, which can be troublesome and stressful.
Apple, AT&T, and Rogers offered Adore as a free delivery add-on. Customers could:
Have their phone delivered by UPS or Canada Post in 1-2 weeks.
Alternately, arrange for a person to visit them the same day (or sometimes even the same hour) to assist them set up their phone and demonstrate how to use it (transferring contacts, switching the SIM card, etc.).
Each Adore Expert brought a van with extra devices and accessories to customers.
Happy customers.
Here’s how Adore and its partners made money:
Adores partners appreciated sending Experts to consumers' homes since they improved customer satisfaction, average sale, and gadget returns.
**Telecom enterprises have low customer satisfaction. The average NPS is 30/100. Adore's global NPS was 80.
Adore made money by:
a set cost for each delivery
commission on sold warranties and extras
Consumer product applications seemed infinite.
A proprietary scheduling system (“The Adore App”), allowed for same-day, even same-hour deliveries.
It differentiates Adore.
They treated staff generously by:
Options on stock
health advantages
sales enticements
high rates per hour
Four-day workweeks were set by experts.
Being hired early felt like joining Uber, Netflix, or Tesla. We hoped the company's stocks would rise.
Exciting times.
I smiled as I greeted more than 1,000 new staff.
I spent a decade in retail before joining Adore. I needed a change.
After a leap of faith, I needed a lifeline. So, I applied for retail sales jobs in the spring of 2019.
The universe typically offers you what you want after you accept what you need. I needed a job to settle my debt and reach $0 again.
And the universe listened.
After being hired as an Adore Expert, I became a Virtual Learning Facilitator. Enough said.
After weeks of economic damage from the pandemic.
This employment let me work from home during the pandemic. It taught me excellent business skills.
I was active in brainstorming, onboarding new personnel, and expanding communication as we grew.
This job gave me vital skills and a regular paycheck during the pandemic.
It wasn’t until January of 2022 that I left on my own accord to try to work for myself again — this time, it’s going much better.
Adore was perfect. We valued:
Connection
Discovery
Empathy
Everything we did centered on compassion, and we held frequent Justice Calls to discuss diversity and work culture.
The last day of onboarding typically ended in tears as employees felt like they'd found a home, as I had.
Like all nice things, the wonderful vibes ended.
First indication of distress
My first day at the workplace was great.
Fun, intuitive, and they wanted creative individuals, not salesman.
While sales were important, the company's vision was more important.
“To deliver joy through life-changing mobile retail experiences.”
Thorough, forward-thinking training. We had a module on intuition. It gave us role ownership.
We were flown cross-country for training, gave feedback, and felt like we made a difference. Multiple contacts responded immediately and enthusiastically.
The atmosphere was genuine.
Making money was secondary, though. Incredible service was a priority.
Jon and Tim answered new hires' questions during Zoom calls during onboarding. CEOs seldom meet new hires this way, but they seemed to enjoy it.
All appeared well.
But in late 2021, things started changing.
Adore's leadership changed after its IPO. From basic values to sales maximization. We lost communication and were forced to fend for ourselves.
Removed the training wheels.
It got tougher to gain instructions from those above me, and new employees told me their roles weren't as advertised.
External money-focused managers were hired.
Instead of creative types, we hired salespeople.
With a new focus on numbers, Adore's uniqueness began to crumble.
Via Zoom, hundreds of workers were let go.
So.
Early in 2022, mass Zoom firings were trending. A CEO firing 900 workers over Zoom went viral.
Adore was special to me, but it became a headline.
30 June 2022, Vice Motherboard published Watch as Adore's CEO Fires Hundreds.
It described a leaked video of Jon Swanson laying off all staff in Canada and the UK.
They called it a “notice of redundancy”.
The corporation couldn't pay its employees.
I loved Adore's underlying ideals, among other things. We called clients Adorers and sold solutions, not add-ons.
But, like anything, a company is only as strong as its weakest link. And obviously, the people-first focus wasn’t making enough money.
There were signs. The expansion was presumably a race against time and money.
Adore finally declared bankruptcy.
Adore declared bankruptcy 3 months after going public. It happened in waves, like any large-scale fall.
Initial key players to leave were
Then, communication deteriorated.
Lastly, the corporate culture disintegrated.
6 months after leaving Adore, I received a letter in the mail from a Law firm — it was about my stocks.
Adore filed Chapter 11. I had to sue to collect my worthless investments.
I hoped those stocks will be valuable someday. Nope. Nope.
Sad, I sighed.
$1.2 billion firm gone.
I left the workplace 3 months before starting a writing business. Despite being mediocre, I'm doing fine.
I got up as Adore fell.
Finally, can we scale kindness?
I trust my gut. Changes at Adore made me leave before it sank.
Adores' unceremonious slide from a top startup to bankruptcy is astonishing to me.
The company did everything perfectly, in my opinion.
first to market,
provided excellent service
paid their staff handsomely.
was responsible and attentive to criticism
The company wasn't led by an egotistical eccentric. The crew had centuries of cumulative space experience.
I'm optimistic about the future of work culture, but is compassion scalable?

Ajay Shrestha
2 years ago
Bitcoin's technical innovation: addressing the issue of the Byzantine generals
The 2008 Bitcoin white paper solves the classic computer science consensus problem.
Issue Statement
The Byzantine Generals Problem (BGP) is called after an allegory in which several generals must collaborate and attack a city at the same time to win (figure 1-left). Any general who retreats at the last minute loses the fight (figure 1-right). Thus, precise messengers and no rogue generals are essential. This is difficult without a trusted central authority.
In their 1982 publication, Leslie Lamport, Robert Shostak, and Marshall Please termed this topic the Byzantine Generals Problem to simplify distributed computer systems.
Consensus in a distributed computer network is the issue. Reaching a consensus on which systems work (and stay in the network) and which don't makes maintaining a network tough (i.e., needs to be removed from network). Challenges include unreliable communication routes between systems and mis-reporting systems.
Solving BGP can let us construct machine learning solutions without single points of failure or trusted central entities. One server hosts model parameters while numerous workers train the model. This study describes fault-tolerant Distributed Byzantine Machine Learning.
Bitcoin invented a mechanism for a distributed network of nodes to agree on which transactions should go into the distributed ledger (blockchain) without a trusted central body. It solved BGP implementation. Satoshi Nakamoto, the pseudonymous bitcoin creator, solved the challenge by cleverly combining cryptography and consensus mechanisms.
Disclaimer
This is not financial advice. It discusses a unique computer science solution.
Bitcoin
Bitcoin's white paper begins:
“A purely peer-to-peer version of electronic cash would allow online payments to be sent directly from one party to another without going through a financial institution.” Source: https://www.ussc.gov/sites/default/files/pdf/training/annual-national-training-seminar/2018/Emerging_Tech_Bitcoin_Crypto.pdf
Bitcoin's main parts:
The open-source and versioned bitcoin software that governs how nodes, miners, and the bitcoin token operate.
The native kind of token, known as a bitcoin token, may be created by mining (up to 21 million can be created), and it can be transferred between wallet addresses in the bitcoin network.
Distributed Ledger, which contains exact copies of the database (or "blockchain") containing each transaction since the first one in January 2009.
distributed network of nodes (computers) running the distributed ledger replica together with the bitcoin software. They broadcast the transactions to other peer nodes after validating and accepting them.
Proof of work (PoW) is a cryptographic requirement that must be met in order for a miner to be granted permission to add a new block of transactions to the blockchain of the cryptocurrency bitcoin. It takes the form of a valid hash digest. In order to produce new blocks on average every 10 minutes, Bitcoin features a built-in difficulty adjustment function that modifies the valid hash requirement (length of nonce). PoW requires a lot of energy since it must continually generate new hashes at random until it satisfies the criteria.
The competing parties known as miners carry out continuous computing processing to address recurrent cryptography issues. Transaction fees and some freshly minted (mined) bitcoin are the rewards they receive. The amount of hashes produced each second—or hash rate—is a measure of mining capacity.
Cryptography, decentralization, and the proof-of-work consensus method are Bitcoin's most unique features.
Bitcoin uses encryption
Bitcoin employs this established cryptography.
Hashing
digital signatures based on asymmetric encryption
Hashing (SHA-256) (SHA-256)
Hashing converts unique plaintext data into a digest. Creating the plaintext from the digest is impossible. Bitcoin miners generate new hashes using SHA-256 to win block rewards.
A new hash is created from the current block header and a variable value called nonce. To achieve the required hash, mining involves altering the nonce and re-hashing.
The block header contains the previous block hash and a Merkle root, which contains hashes of all transactions in the block. Thus, a chain of blocks with increasing hashes links back to the first block. Hashing protects new transactions and makes the bitcoin blockchain immutable. After a transaction block is mined, it becomes hard to fabricate even a little entry.
Asymmetric Cryptography Digital Signatures
Asymmetric cryptography (public-key encryption) requires each side to have a secret and public key. Public keys (wallet addresses) can be shared with the transaction party, but private keys should not. A message (e.g., bitcoin payment record) can only be signed by the owner (sender) with the private key, but any node or anybody with access to the public key (visible in the blockchain) can verify it. Alex will submit a digitally signed transaction with a desired amount of bitcoin addressed to Bob's wallet to a node to send bitcoin to Bob. Alex alone has the secret keys to authorize that amount. Alex's blockchain public key allows anyone to verify the transaction.
Solution
Now, apply bitcoin to BGP. BGP generals resemble bitcoin nodes. The generals' consensus is like bitcoin nodes' blockchain block selection. Bitcoin software on all nodes can:
Check transactions (i.e., validate digital signatures)
2. Accept and propagate just the first miner to receive the valid hash and verify it accomplished the task. The only way to guess the proper hash is to brute force it by repeatedly producing one with the fixed/current block header and a fresh nonce value.
Thus, PoW and a dispersed network of nodes that accept blocks from miners that solve the unfalsifiable cryptographic challenge solve consensus.
Suppose:
Unreliable nodes
Unreliable miners
Bitcoin accepts the longest chain if rogue nodes cause divergence in accepted blocks. Thus, rogue nodes must outnumber honest nodes in accepting/forming the longer chain for invalid transactions to reach the blockchain. As of November 2022, 7000 coordinated rogue nodes are needed to takeover the bitcoin network.
Dishonest miners could also try to insert blocks with falsified transactions (double spend, reverse, censor, etc.) into the chain. This requires over 50% (51% attack) of miners (total computational power) to outguess the hash and attack the network. Mining hash rate exceeds 200 million (source). Rewards and transaction fees encourage miners to cooperate rather than attack. Quantum computers may become a threat.
Visit my Quantum Computing post.
Quantum computers—what are they? Quantum computers will have a big influence. towardsdatascience.com
Nodes have more power than miners since they can validate transactions and reject fake blocks. Thus, the network is secure if honest nodes are the majority.
Summary
Table 1 compares three Byzantine Generals Problem implementations.
Bitcoin white paper and implementation solved the consensus challenge of distributed systems without central governance. It solved the illusive Byzantine Generals Problem.
Resources
Resources
Source-code for Bitcoin Core Software — https://github.com/bitcoin/bitcoin
Bitcoin white paper — https://bitcoin.org/bitcoin.pdf
https://www.microsoft.com/en-us/research/publication/byzantine-generals-problem/
https://www.microsoft.com/en-us/research/uploads/prod/2016/12/The-Byzantine-Generals-Problem.pdf
Genuinely Distributed Byzantine Machine Learning, El-Mahdi El-Mhamdi et al., 2020. ACM, New York, NY, https://doi.org/10.1145/3382734.3405695
