Bitcoin Mining Notes

Unit Six: Bitcoin Mining

16.1 The Task of Bitcoin Miners

Overview

Bitcoin mining shares similarities with gold rushes, presenting challenges and risks. To become a Bitcoin miner, one must join the Bitcoin network and connect to other nodes.

Tasks Performed by Bitcoin Miners
  1. Listen for Transactions: Validate transactions by checking signatures and ensuring outputs haven't been spent.

  2. Maintain Blockchain: Obtain historical blocks and listen for new blocks.

  3. Validate Blocks: Validate each transaction and check for a valid nonce.

  4. Assemble a Candidate Block: Group valid transactions into a new block.

  5. Find a Valid Nonce: Requires significant computational work.

  6. Hope for Acceptance: No guarantee a block will be accepted.

  7. Profit: Receive block rewards (25 bitcoins in 2015) and transaction fees.

Transaction fees have been a modest source of income, about 1% of block rewards.

Classification of Miner Tasks
  1. Validating Transactions and Blocks:

    • Essential for the Bitcoin network.

    • Help the Bitcoin network and are fundamental to its existence.

    • The reason that the Bitcoin protocol requires miners in the first place.

  2. The Race to Find Blocks and Profit:

    • Incentivize miners to perform essential steps.

    • Necessary for Bitcoin to function as a currency.

6.1.1 Finding a Valid Block

Process
  1. Compile valid transactions into a Merkle tree.

  2. Create a block with a header pointing to the previous block.

  3. The block header includes a 32-bit nonce field.

  4. Try different nonces to find one that causes the block's hash to be under the target.

Nonce
  • Begin with a nonce of 0 and increment by one.

  • If every possible 32-bit value for the nonce doesn't produce a valid hash, additional changes are needed.

  • Use an extra nonce field in the coinbase transaction.

  • After exhausting all nonces for the block header, increment the extra nonce in the coinbase transaction and search nonces in the block header once again.

Changing the Coinbase Nonce

Changing<br>once<br>coinbase<br>ewlinetransactionChanging<br>once<br>coinbase<br>ewline transaction The entire Merkle tree of transactions has to change.

Expensive Operation

Changing the extra nonce in the coinbase transaction is more expensive than changing the nonce in the block header.

Exhaustion

Miners spend most of their time changing the nonce in the block header and only change the coinbase nonce when they have exhausted all 2322^{32} possible nonces in the block header without finding a valid block.

Difficulty

As of the end of 2015, the mining difficulty target (in hexadecimal) is:

0000000000000000295500000000000000000000000000000000000000000000

The hash of any valid block has to be below this value.

<1
in
ewline about
ewline 2^{68}
once nonces that you try will work.

Analogy

The number of possible nonces is greater than the human population of Earth squared. If every person on Earth was their own planet Earth with 7 billion people on it, the total number of people would be about 2652^{65}.

16.1.2 Determining the Difficulty

The mining difficulty changes every 2,016 blocks and is adjusted based on how efficient the miners were over the period of the previous 2,016 blocks.

Formula

NextDifficulty=PreviousDifficulty<br>ewline201610<br>ewlineMinutesTimetoMineLast2016BlocksNextDifficulty = PreviousDifficulty * <br>ewline \frac{2016 * 10<br>ewline Minutes}{TimetoMineLast2016Blocks}

The intent of this formula is to maintain the property that blocks should be found on average once every 10 minutes.

Period

There's nothing special about 2 weeks, but it's a good trade-off. If the period were shorter, the difficulty might fluctuate. If the period were longer, the network's hash power might get too far out of balance with the difficulty.

Independent Computation

Each Bitcoin miner independently computes the difficulty and will only accept blocks that meet the difficulty that they computed

Consensus

Miners who are on different branches might not compute the same difficulty value, but any two miners mining on top of the same block will agree on what the difficulty should be.

Mining Difficulty Over Time

Mining difficulty keeps increasing, depending on activity in the market and factors such as new miners joining and the exchange rate of Bitcoin.

Hash Rate

Generally, as more miners come online and mining hardware gets more efficient, blocks are found faster, and the difficulty is increased, so that it always takes about ten minutes to find a block.

Step Function

The difficulty is a step function because it is only adjusted every 2,016 blocks.

Block Generation Time

Shows how many seconds elapse between consecutive blocks in the block chain.

Difficulty Reset

Every 2,016 blocks, the difficulty resets, and the average block time goes back up to about 10 minutes.

Growth Rate

Calculations show that this requires an astonishing 25 percent growth rate every 2 weeks, or several hundredfold per year.

Steady State

As mining is closer to a steady state, the period to find each block stays much closer to 10 minutes.

Difficulty Decrease

It can even take longer than 10 minutes, in which case there will be a difficulty decrease.

Death Spiral

One proposed scenario for Bitcoin's collapse is a "death spiral," in which a dropping exchange rate makes mining unprofitable for some miners, causing an exodus, in turn causing the price to drop further.

6.2 Mining Hardware

Core Computation

The core of the difficult computation miners are working on is the SHA256 hash function.

SHA-256

SHA-256 is a general-purpose cryptographic hash function that's part of a bigger family of functions that was standardized in 2001 (SHA stands for Secure Hash Algorithm).

256-bit State

SHA-256 maintains 256 bits of state. The state is split into eight 32-bit words, which makes it highly optimized for 32-bit hardware.

Iterations

A complete computation of SHA-256 does this for 64 iterations. During each round, slightly different constants are applied, so that no two iterations are exactly the same.

Manipulation

The task for miners is to compute this function as quickly as possible. To do this, they need to be able to manipulate 32-bit words, perform 32-bit-modular addition, and also do some bitwise logic.

Double Application

Bitcoin actually requires SHA-256 to be applied twice to a block to get the hash used by the nodes. The reasons for the double computation are not fully specified.

6.2.2 CPU Mining

First Generation

The first generation of mining was all done on general-purpose central processing units (CPUs).

Code

Miners simply searched over nonces in a linear fashion, computed SHA-256 in software, and checked whether the result was a valid block.

Double SHA-256

SHA-256 is applied twice

Speed

On a high-end desktop, you might expect to compute about 20 million hashes per second. At that speed, it would take you several hundred thousand years on average at the early-2015 difficulty level (2672^{67}) to find a valid block.

Profitability

CPU mining is no longer profitable at the current level of difficulty.

6.2.3 GPU Mining

Second Generation

People started using their graphics cards, or graphics processing units (GPUs), instead of CPUs.

Design

GPUs are designed to have high throughput and high parallelism, which are useful for Bitcoin mining. Bitcoin mining can be parallelized easily.

OpenCL

In 2010, the language OpenCL was released. OpenCL is a general-purpose language to do things other than graphics on a GPU. This paved the way for Bitcoin mining on GPUs.

Properties
  • Easily available and easy for amateurs to set up.

  • Most accessible high-end hardware available to the general public.

  • Designed for parallelism.

  • Some GPUs have specific instructions to do bitwise operations.

  • Most GPUs can be overclocked.

Overclocking

Say you can run your GPU 50 percent faster, but doing so will cause errors in the SHA-256 computation up to 30 percent of the time

Throughput

In the above example, the throughput is 1.5x compared to not overclocking, whereas the success rate is 0.7x. The product is 1.05 expected profits by 5 percent.

Multiple GPUs

You can drive many GPUs from one motherboard and CPU. So you can attach multiple graphics cards to the computer that runs your Bitcoin node.

Disadvantages
  • GPUs have a lot of video processing hardware that can't be used for mining.

  • A large number of floating-point units are not used in SHA-256.

  • GPUs don't have optimal thermal characteristics.

  • Can overheat when stacked.

  • consume a fairly large amount of power.

  • You had to either build your own board or buy expensive boards to house multiple graphics cards.

  • On a really high-end GPU with aggressive tuning, you might get as high as 200 million hashes per second.

Demise

GPU mining is basically dead for Bitcoin today.

6.2.4 Mining with Field-Programmable Gate Arrays

Third Generation

Around 2011, some miners started switching from GPUs to field programmable gate arrays (FPGAs).

Verilog

The first implementation of Bitcoin mining came out in Verilog, a hardware design language used to program FPGAs.

Rationale

Approximate the performance of custom hardware while allowing customization or reconfiguration.

Advantages
  • Offer better performance than GPUs, particularly on "bit fiddling" operations.

  • Cooling is easier.

  • You can theoretically use nearly all of the transistors on the card for mining.

  • Can pack many FPGAs together and drive them from one central unit.

Throughput

Using an FPGA with a careful implementation, you might get up to 1 gigahash per second, or a billion hashes per second.

Limitations
  • Malfunctions due to being driven harder than designed for.

  • Difficult to optimize the 32-bit addition step.

  • Less accessible.

  • Marginally improved cost-performance over GPUs.

Duration

The days of FPGA mining were far more limited, lasting only a few months before customized chips arrived.

6.2.5 Mining with Application-Specific Integrated Circuits

Current Era

Mining today is dominated by Bitcoin application-specific integrated circuits (ASICs).

Design and Optimization

These are chips that are designed, built, and optimized for the sole purpose of mining bitcoins.

Expertise Required

Designing ASICs requires considerable expertise, and their lead time is also quite long.

Turnaround

This may be the fastest turnaround time from specifying a problem to delivering working chips in the history of integrated circuits.

Issues

The first few generations of Bitcoin ASICS were quite buggy, most didn't deliver the promised performance numbers.

Lifetime

Until 2014 the lifetime of ASICS was quite short, with most boards in the early ASIC era becoming obsolete in about 6 months.

Profits

During this time, the bulk of the profits were made up front. Often miners made half of the expected profits for the lifetime of the ASIC during just the first 6 weeks of using the chips

Shipping

Shipping speed became a crucial factor in making a profit.

Frustrated customer

Due to the immaturity of the industry, consumers often experienced shipping delays, with boards nearly obsolete by the time they arrived.

Economics

For much of Bitcoin's history, the economics of mining haven't been favorable to the small miner who wants to go online, order mining equipment, and start making money

Prediction

In most cases, people who placed orders for mining hardware should have lost money based on the rapid increase in mining difficulty.

Bitcoin exchange rate

However, until 2013 the exchange rate of Bitcoin rose enough to prevent most miners from losing money outright

Investment advice

In effect, mining has been an expensive way to bet that- the price of Bitcoin would rise, and many miners- even though they've made money mining Bitcoins would have been better off if they had just taken the money that they were going to spend on mining equipment, invested- it in bitcoins, and eventually sold them at a profit.

Caution

However, mining is not an advisable way to make money. Most ASICS sold commercially today are unlikely to pay for themselves in mining rewards once you factor in the price of electricity and cooling.

6.2.6 Professional Mining Today

Shift

Today mining has mostly moved away from individuals and toward professional mining centers.

Operation

Exact details about how these centers operate are not well known, because companies protect their setups to maintain a competitive advantage.

Profitability

Presumably, these operations maintain profitability by buying at a bulk discount slightly newer and more efficient ASICs than are available for sale to most individuals.

Considerations

When determining where to set up a mining center, the three biggest considerations are climate, cost of electricity, and network speed.

  • Want a cold climate to keep cooling costs low

  • Cheap electricity

  • Fast network connection to be well connected to other nodes

Popular destinations

Georgia and Iceland have reportedly been popular destinations for Bitcoin mining data centers

6.2.7 Similarities to Gold Mining

Parallels

Interesting parallels between Bitcoin mining and gold mining.

Gold rush mentality

Both saw a similar gold rush mentality with many young, amateur individuals eager to get into the business as soon as possible.

Evolution parallels

Bitcoin mining evolved from using CPUs, to GPUs, to FPGAs, and now to ASICS. Gold mining evolved from individuals with gold pans; to small groups of people with sluice boxes; to placer mining. to modern gold mining.

Accessibility

For Bitcoin and gold mining, the friendliness toward and accessibility by individuals has gone down over time, and large companies have consolidated most of the operations (and profits).

equipment sales

Another pattern that has emerged in both endeavors is that most of the profits have been earned by those selling equipment, whether gold pans or mining ASICS, at the expense of individuals hoping to strike it rich.

6.2.8 The Future

Domination of ASIC

Currently ASIC mining is the only realistic means to be profitable in Bitcoin, it's not very friendly to small miners.

Questions

raises a few questions about what will happen going forward.

  • Are small miners out of Bitcoin mining forever, or is there a way to reincorporate them?

  • Does ASIC mining and the development of professional mining centers violate the original vision of Bitcoin?

Satoshi Nakamoto's vision

Which was to have a completely decentralized system in which every individual in the network mined on their own computer?

CPU only system

If this is indeed a violation of Satoshi Nakamoto's original vision for Bitcoin, would we be better off with a system in which the only way to mine is with CPUs?

6.2.9 The Cycle Repeats Itself

Altcoins

Several smaller altcoins have indeed used a different puzzle than SHA-256, but have experienced a trajectory in mining that is similar to Bitcoin's.

Lead time

For ASICS, there is still a long lead time between designing a chip and shipping it, so if a new altcoin uses a new puzzle (even if only anmodified version of SHA-256), this will buy some time in which ASICS are not yet available.

Altcoin strategy

mining will proceed just Bitcoin did: from CPUs to GPUS and/or FPGAs to ASICS (if the altcoin is very successful, e.g., LiteCoin).

Pioneer new altcoins

One strategy for smaller miners may be to try to pioneer new altcoins that aren't yet valuable enough for large mining groups to invest in just like small gold miners who have been driven out of proven goldfields might try prospecting unproven new areas.

Significant risk

Of course, such pioneers would face a significant risk that the novel altcoin will never succeed.

6.3 Energy Consumption and Ecology

Concerns

We saw how large professional mining data centers have taken over the business of Bitcoin mining, and how this parallels the movement to pit mining in gold mining. You may be aware that pit mines have been a major source of concern over the years due to the damage they cause to the environment Bitcoin is not quite at that level yet, but it is starting to use a significant amount of energy

Impact

has become a topic of discussion. In this section we discuss how much Bitcoin mining is using and what the are for both the currency and our planet.

6.3.1 Thermodynamic Limits

Landauer's principle

A physical law developed by Ralph Landauer in the 1960s states that any irreversible computation must use a minimum amount of energy Logically, irreversible computations can be thought of as those that lose information Specifically, the principle states that erasing any bit must consume a minimum of kT<br>ewlineln2kT<br>ewline ln2 joules

The Formula

Where k is the Boltzmann constant (approximately 1.3810231.38 * 10^{-23} joules per kelvin), T is the temperature of the circuit in kelvins, and ln2ln2 is the natural logarithm of 2, roughly 0.69.

Tiny Energy

This is a tiny amount of energy per bit, but it does provide a hard lower bound on energy usage from basic physics.

Implication

Every time you flip one bit in an irreversible way, a minimum number of joules has to be used. Energy is never destroyed it's converted from one form to another. In the case of computation, the energy is mostly transformed from electricity, which is useful, high- grade energy, into heat, which dissipates in the environment.

Irreversible

As a cryptographic hash function, SHA-256 is not a reversible computation. This is a basic requirement of cryptographic hash functions.

Energy Consumption

So, since irreversible computation has to use some energy, and SHA-256 the basis of Bitcoin mining is not reversible energy consumption is an inevitable result of Bitcoin mining

Efficiency

That said, the limits placed by Landauer's principle are far below the amount of electricity that is being used today. We're nowhere close to the theoretical optimal consumption of computing.

How Bitcoin mining uses energy

  1. Embodied Energy

  2. Electricity

  3. Cooling

Embodied Energy

Bitcoin mining equipment needs to be manufactured This requires physical mining of raw materials as well as turning these raw materials into a Bitcoin mining ASIC, both of which require energy. This is the embodied energy

Future Trends

Hopefully, over time the embodied energy will go down as less and less new capacity comes online. As fewer people are buying new mining ASICS, the equipment will become obsolete less quickly, and the embodied energy will be amortized over years of mining.

Electricity

When your ASIC is powered on and mining, it consumes electricity This is the step that we know has to consume energy due to Landauer's principle

Rig efficiency

As mining rigs become more efficient, the electrical energy costs will go down

Permanent necessity

we know that they will never disappear; electrical energy consumption will be a fact of life for Bitcoin miners forever.

Cooling Costs

Bitcoin mining equipment needs to be cooled to prevent it from malfunctioning If you're operating at a small scale in a cold climate, your cooling costs might be trivial

extra costs

Even in cold climates, once enough ASICS are packed in a small space, you're going to have to pay extra to cool off your equipment from all the waste heat that it is generating. Generally, the energy
used to cool off mining equipment will also be in the form of electricity.

6.3.2 Mining at Scale

Embodied energy

Both embodied energy and electricity decrease (per unit of mining work completed) when operating at a large scale It's cheaper to build chips that are designed to run in a large data center, and you can deliver the power more efficiently, because you don't need as many power supplies

Cooling

When it comes to cooling, however, the opposite is usually true: cooling costs tend to increase the larger your scale is. If you want to run a large operation and have a lot of Bitcoin mining equipment all in one place, there's less air for the heat to dissipate into in the area surrounding your equipment. Your cooling budget will therefore increase at scale (per unit of mining work completed)

6.3.3 Estimating Energy Usage

Impossible precision

How much energy is the entire Bitcoin system using? Of course, we can't compute this precisely, because it's a decentralized network with miners operating all over the place without documenting exactly what they're doing.

Approaches to estimating
  1. Top-Down Approach

  2. Bottom-Up Approach

These figures are very rough, both because some of the parameters are hard to estimate and because they change quickly At best they should be treated as order-of-magnitude estimates.

Top-Down Approach

start with the simple fact that every time a block is found today, 25 bitcoins, worth about $6,500, are given to the miners. That's about $11 every second being created out of thin air in the Bitcoin economy and given to the miners

Calculation

If Bitcoin miners were spending all $11 per second of earnings buying electricity, they could purchase (367) megajoules per second, consuming a steady 367 megawatts.

Bottom-Up Approach

Ask this question: if the miners were turning all of that $11 per second into electricity, how much can they buy?

Industrial Electricity

Electricity costs about $0.10 per kilowatthour at an industrial rate in the United States, or equivalently, $0.03 per megajoule.

Hash Count

look at the number of hashes the miners are actually computing, which we know by observing the difficulty of each block

Most Efficient Hardware

If we then assume that all miners are using the most efficient hardware, we can derive a lower bound on the electricity consumption

Commercial Availability

Currently, the best claimed efficiency among commercially available mining rigs is about 3 gigahashes per second per watt.

Calculation

The total network hash rate is about 350,000,000 gigahashes per second, or equivalently, (350 petahashes per second.

Power Consumption

multiplying these two together, we see that it takes about 117 megawatts to produce that many hashes per second at that efficiency

What the figure excludes

This figure excludes all of the cooling energy
and all of the embodied energy that is in those chips

ballpark estimate

Combining the top-down and bottom-up approches, we derive a ballpark estimate of the amount of power being used for Bitcoin mining on the order of a few hundred

6.3.4 Is Bitcoin Wasteful?

Analogy

Does Bitcoin mining waste energy?

Scale

What does it mean to say that Bitcoin is consuming perhaps 10 such large power plant's output

Not disproportionate

compared
to all the other ways that we waste electricity for non-essential processes,

Serving a specific need

Bitcoin wastes energy, because it is hard to know if it is justified

Currency support

Maintaining the current currency system considerible energy is used up on
Agencies, currency proccesing services, as maintaining

If it is valuable.

So if we value Bitcoin as a useful currency system, then the energy required to support it is not really being wasted

alternative solutions

Still, it would be advantageous if we could replace Bitcoin mining with a less energy- intensive

What is an energy-intensive puzzle

and still have a secure currency.

6.3.5 Repurposing Energy

find a way to make more eco- friendly with Bitcoin

Data Furnace

Instead of buying a tradition electronic heat
What if it was heat to buy a furnace doubling as a Bitcoin miner

Electric Heater

There are few draw backs to this approach heat is as efficient as the furnace, and is as complicated to plug in the average electric heater

Drawbacks

Although is about as efficient to using as a electric heater much less efficient than gas heaters. Mining hashrate might go down seasonally based on how much heat do people need, might happen that in warmer weather mining might power down

Digital laws

The question of ownership is not clear. If you own a bitcoin furnace, do you get the Bitcoin mining rewards that the heater makes for you.

6.3.6 Turning Electricity into Cash

Bitcoin mining provides the most electrical form. In cost means the effects open to all for new forms of abuse

Energy Subsidies

Subsidized Electricity is intended on bringing buissniess That will give labour to the market and economy bitcoin may not attract this

Biggest issue

Out lets where people may plug this bitcoin miners to gain profits with others

Consideration

Monitor every power outlet in the world to look out for miners

6.4 Mining Pools

Miner income

Consdier the income and ecnomics of a small ammount of money you spend to by shiny new bit coin
Every 14 months the performance is such that
You will gain back from bit coin
$400 a month

Random Proccess

You donr ear nonthing until the next block come, mining is a random process.

6.4.1 High Variance

Risk

Historically when small busniess people deal with high risks they join each other for help. Farmers for example agree that their profits will be shared to each other if there bar fires downd

Mining pool solution

A pool where miner attempts to mine a group, pool manager where nonnesense is called noncence called pool manager is accepted, the reward, pool manager will distrbute the revernue from the pool for each of the mining process.

6.4.3 Mining Shares

Near valid blocks

miners can prove porbailisticly from how much they output from miner for near valid blocks

Proving work

miners show some sort of near valid blocks for miner to show there working at it.

Process

Pool manager will also run a bitcoin node and collecting all the transications in a block, the manager will send the bock to all particapants in the pool, so that they send send and approve

6.4.4 Proportional

In the process of the pool the money will be shared to them based of how much they put

The model

In the proportioal mode miners beer a ammout risk, in a large enough group miners the variance, and a higher risk for pool managers
In the proportional the pool mnagers have too verify the reward in how much did miners contibuted, it tskes to long to verify.

6.4.5 Pool Hopping

Switching pools

Miners are motivated to switch to different pools on differnt times, effectivly and will quickly get the block in.

Incentive in practice

Miners tend to find and be motivated ealry what to do to gain profit. In order to make the pool what they need to make good of
And switch depending on pool
What they expected is low.

Incomplete practice

Proportional Pools arent really practical, for a more comlpicated schemes like per N shares are submist.

6.4.6 History and Standardization

Start of pools

Mining pools first started aroudn gpu ear, it came quit quick by how it helped miners from losing risk.

There have been sugesstion that it needs to be standarized

Commutation

A programmibg interface for communicatio to send miners there work and the miner sents it to the pool back to send shares there finding

Minor inconvienece

The protocol is only a minor incoviece because to multplie incpativeable to mining pool protocol

6.4.7 51 Percent Mining Pools

solo mining

Nearly all miners are mining through pools, very feel miners mile sloy anymore.

Largest mining pool

Is one the largese mining pool got so big that they it more then what it needs.
This is something that the communitys has feared for along time it leading for A backslash on this big giant pool

Market Share

Has gone town by design.
For the pool that stopped new participat

concentration

Still two mining pool controlled the ecnormus power for the mining process.
This created the situatuion that it has not been atleased supercisially by how the situation looked on those times.
It still a concern that one of the pool acuring to mining power.

Hidden

actual concentration by how it particapate and hides them true color.
How is it to control the control of mining hardware.

6.4.8 Are Mining Pools Beneficial?

Benefits

The advantages of mining pools that it more prditcable, and it easer from small timer ti get involed in the game.
Withoud mining pools the variance will make many small time miners infeasibale.

Upgrading Netwrok

another advtanges that there is one poll mnager, to upgrade, so thers only so much, to update on software

Disadvantages

Ammount of open quiestion what has the actial amount to what the operator actually have, but is unclear it does happen in time.

Chain store

Another dsavtage is that reuduces how amout ammount of particpatn going to use
Pevoiusly it was a need where to have miner to run the full bicoin code.
They need all had to have the chain and vlaid every transiaciton.
Now moost miners will to there POOL manager
That is one of the reasion this is is reasions the nuermber is decreasing

6.5 Mining Incentives and Strategies

Default decisions

there are many decision make miners and is defauliing
And is possilbel that by defaluting you will get more profits. active area for scinerio straegris.
In any in the following discussion and we can a not deaulting miner controlls power in the power a.

6.5.1 Fork Attack

The simplest attck that can profited is that there 1is a dobule spend, sends the money from bib, is payments for any services used and included chains perhas[s from commin heirstic form, and to awiat xis confirmatio to be sure
Cincvd that bob have been perform or sells goods

Beginning Work

For an eraelir bofore contian transiaciotn from cob for forkchain.
The miner insnters double amount for cpins in paid or transion the mined to address form the chain.

For attack sucess to what is going to happen is not sucess the frork chainn that will do onger chains form payment from block chains. .if the attack minaers ha have. In the random Varration form bloock the chan to grower and onger.
Practical and what the attcker will do

For atackers might give the attcker long term potential.

Motivation and damage by losing comfidence for 51 percen of hashing will be the destroyment of currency for in the short term from doubel spedning, the migth serisously undermind there long term gaining and by the end result you
Destroyed exchange

Attack could possible crash the bitcoin exchange and exchange that the a exchange would as particpatents move wealth there way form the system

6.5.2 Forking Attack via Bribery

Easier way

Buying enough hard ware in the hash of the eapensive task. And by bribing it would be it would be an easer way to launch the forikn attacak

By cash ore Envelop of cash

You couold brive miners by several way. Create and for running mining pool and create lost.
For grreat infetives then any other other pools do. Even thought the incetive may. Not be sustatinable. an acttack to keep giong log enoughtto lancuh forking atacck

mechanics

cashing they are is instead of actually all minign you jus pay them on hlep.

Won want to help beucse would hurt what they a
Invest on, but in even though they do miners would not defect because to short term money but the short team and is not viable

6.5.3 Temporary Block withholding Attacks

Behavior

After if you find and announcment in temproa blocking attaack. and you not announcment . insdtead try to ge ahread done doon soem more mining and in hopes of what you fonded.
If you the block form of all what is and it can get pretty bad and and is the network be other miers to the mining powerr to the mining rewardds

Fortune Favors

Someone could just release a block one block a head.
And creasing it to a block form to ever miner.
And