What is Nonces , mining, and quantum computing

the one to generate the random number

how is it protected from us to know it

what makes the that random number itself

tamper proof is the whole network

contributing to the random number all

right so the nonce the random number is

calculated independently billions and

billions and billions of times per

second by each mining hardware system so

when a miner is mining what they're

doing essentially is coordinating over

network a very large number of mining

computers and these mining computers are

calculating billions of nonces per

second and there's nothing manual about

this by the way this when we say a miner

is mining a announces being calculated

there's no one sitting there doing a

calculation or validating transactions

or clicking a proof these are completely

automated unattended operations that

happen where computers calculate

billions of nonces per second so what is

the purpose of the nonce the nonce is

simply a random number and it's a very

large random number the space for an

ounce is bits which gives billion

possible combinations but there's also

some extra space in the block which is

called extra notes and extra months

really allows you to expand that to much

more than bits so you can try many

many many many billions upon billions of

combinations you're gonna hear me say

billions and billions again and again in

this talk because these numbers are

truly very very large so the purpose of

the nonce is to plug it in to the block

header in the specific location in the

block header that is for the nonce and

then calculate a new block header hash

and when you put the header information

plus the nonce into the hashing

algorithm you'll get a hash

a number will pop out it's a bit

number now that number has to start with

a lot of zeros if it doesn't you try

again with another nonce so the only

part of the header you can change is the

nots so when the minor is mining what

they're doing is they're constructing a

block they're putting all of the

transactions and the other information

into the header the timestamp etc etc

and then once they've got that header

they plug in a nonce any notes let's say

the number one and then they calculate

the header hash and they look to see if

it matches this special pattern which is

that it starts with a lot of zeros and

the chances of it starting with a zero

well they get lower the more zeros you

expect to find at the beginning of the

number but in the in the beginning let's

say you're looking just for one bit to

be zero then about half the hashes you

produce will have a zero bit in the

beginning and half the hashes will have

a one if you want to zeros in the

beginning that it's a one in four chance

if you want three zeros in the beginning

then it's a one and eight chances you

want four zero bits in the beginning

then it's a one in chance and by the

time you get to the numbers we see with

blocks today we're looking about one in

five septillion chance of you having

that many zeros at the beginning of the

block and how do you find the one in

several septillion chances well you try

a septillion times per second and you do

that by trying as many possible

different nonces with a header you've

constructed one of the miners is going

to be lucky in one of those attempts

they will find nonce that when fitted

into the block that they've constructed

as a candidate will produce a header

that has this many bits of zeros in the

beginning that match

as the pattern matches the difficulty

required by the network and that is a

winning block that is a valid block and

as soon as they found that they can then

announce this random number so the

random number isn't tamper proof it's

not secret and the mining pool doesn't

pick this random number every mining

machine out there is trying billions of

these random numbers every second and

they discard all of the results until

they find one random number if it

produces a hash that has this particular

property it starts with a lot of zeros

heceta asks is it possible to develop an

algorithm for guessing announce which

will fast-track solving the Bitcoin

challenge by a miner could that be

related to the recent shattering of

sha- yes that's an excellent question

Oh Sita in fact yes there is the

possibility of creating a shortcut that

allows you to predict the value that is

required and announce in order to

produce proof of work of a specific

target that would involve breaking

shattering if you like sha- sha- was

recently shattered as the popular

expression goes meaning that the sha-

cryptographic algorithm hurts or graphic

hashing algorithm sorry has been

compromised in such a way that you can

Det you can create a collision that

means that you can produce a specific

pre image to the cryptographic hash

algorithm which will result in a desired

hash as its output that ability to

produce a desired hash from a pre-image

that is identical perhaps to another to

the fingerprint of another pre image a

collision as it's called is a fatal flaw

and if you discover a fatal flaw in an

algorithm as has been discovered in

sha- then that algorithm is no longer

suitable as a cryptographic hash

algorithm you cannot use it for the

purpose of fingerprinting documents

cannot use it for the purpose of for

example fingerprinting Digital Keys

certificates SSL cryptographic keys and

the integrity of messages that are

validated through cryptographic hash

algorithms and sha- can no longer be

used for those purposes because it has

been fatally compromised

however Bitcoin mining uses sha-

sha- is enormous ly more complicated

to compromise so every cryptographic

algorithm has a certain shelf life on

average to years before a

cryptographic algorithm can no longer be

considered secure depending on the

cryptographic algorithm the shelf life

if you like for that algorithm may be

greater or lesser some have weaknesses

that are discovered which shorten the

shelf life make it easier to find a

shortcut to compromise most

cryptographic algorithms are based on

some kind of trapdoor function a

mathematical function that has no

shortcut where the amount of computation

required to go one way through the

algorithm versus to go the opposite way

is immense and as long as you can't find

the shortcuts that algorithm is secure

to a certain amount of computation if

there is no shortcut sha-

will continue to be secure for decades

and decades longer if a compromise is

found or some kind of shortcuts that

doesn't mean it's fatal it doesn't

necessarily immediately invalidate the

algorithm it may weaken it by a certain

percentage so it may make it twice as

hard

sorry twice as easy to find a suitable

hash or maybe four times as easy to find

this usable hash and that was certainly

by weakening the algorithm shorten its

shelf life because as computing power

continues to develop that means that at

some points it would be viable to break

the algorithm essentially now so far

there is no shortcut that has been

discovered for sha- and

one of the reasons we know that is

because Bitcoin represents effectively a

giant global pinata stuffed with fifteen

billion dollars that if you bash with

the right shortcuts for sha- you can

break it open and collect fifteen

billion dollars or you can collect some

percentage of that before the value

collapses catastrophic ly by breaking

the piata essentially it's a honeypot

Bitcoin represents a global test that

tells us that child to is secure how

do you know sha- is secure

bitcoin is worth fifteen billion and no

one's cracked it yet

now at some point it may become obvious

that sha- is no longer secure or it's

reaching at the end of its life or we

find new vectors that perhaps in a

decade or a longer period of time may

make it insecure at that point the

bitcoin developers in collaboration with

the rest of the community would have to

work to modify the proof-of-work

algorithm and replace it with a more

modern algorithm and certainly that

would be a very big undertaking so

that's how we know that there is no

shortcut to sha- and if bitcoin was

using sha-

then some minor out there today would

have been able to break it and very

quickly every miner out there would have

been able to break his at which point

it's no longer useful as a mining

algorithm is bit quite an incentive for

the development of the quantum computer

I mean being a possible threat to the

network security

doesn't this accelerate the race towards

it do you think miners think about this

at all great question

i'm bitcoin is a honeypot effectively it

provides a bounty for anyone who

produces any type of technology whether

it's a sha- collision that we were

talking about before whether it's a

quantum computing shortcut to sha or to

elliptic curve digital signature

algorithms that may result in

being able to compromise some or part of

Bitcoin or being able to weaken Bitcoin

certainly that provides an incentive so

you can think of Bitcoin as a test

Bitcoin tells us sha- is secure ECDSA

is secure today from any and all threats

and how do we know that it's because it

continues to maintain security over

billion dollars therefore we can assume

that these technologies have not been

compromised yet does it accelerate the

development of these things probably

although I think most of the really

interesting developments in quantum

computing can deliver a far far greater

reward for those who develop these

technologies than simply the fifteen

billion dollars that's tied up in in

Bitcoin because quantum computing has

very broad applications furthermore the

application of quantum computing to

Bitcoin is marginal at best

first of all sha- and cryptographic

hash algorithms like sha are not

particularly easy to optimize using

quantum algorithms and let's take curved

digital signature algorithm an elliptic

curve cryptography can be massively

optimized with quantum computing and

quantum algorithms for doing the

elliptic curve factoring in fact du will

exist and they will allow someone to

break elliptic curve cryptography

eventually in fact our large elliptic

prime fields elliptic curve fields for

now the elliptic curves that we used are

far greater in the field that's used for

the elliptic curve is far greater than

any quantum computer can factor so

that's not a risk at some point it would

become a risk and at that point you have

very very powerful quantum computers

that can do that and then the security

of elliptic curve cryptography is no

longer good but elliptic curve

cryptography can be replaced in Bitcoin

by other algorithms and because of the

mechanism by which public keys are not

demonstrated to the network until an

amount is spent if you follow the best

practice of only using an address once

for each transaction then the only time

your public key is demonstrated to the

network shown to the network is when

you've spent the amount of Bitcoin that

was in that address and therefore even

if you were able to break public keys as

used in elliptic curve cryptography you

wouldn't have any Bitcoin to get behind

it because it was only ever used once

Bitcoin addresses of course are secured

through two applications of hashing

algorithms sha- and ripe MD and

those are far less susceptible those two

algorithms as well as the mining

algorithm on sha- as well are far

less susceptible to quantum algorithm

optimizations as far as we know and

therefore it may be a very long time

until quantum cryptography has any

impact on Bitcoin and of course the

other thing to consider is it also

depends on how broadly quantum

cryptography is available if sorry

quantum computing is available if

quantum computing is broadly available

then just as much as you can make better

algorithms for cracking keys you can

also make better algorithms for making

keys you can make quantum mining

algorithms you can make quantum

cryptography algorithms so if quantum

cryptography is very quantum computing

is broadly available then I can use

quantum computing to do encryption and

digital signatures and mining and then

the fact that others have quantum

computing doesn't make any difference

because my cryptography my digital

signatures and my mining algorithm

adjust to secure so really it's about

the unequal availability of quantum