Yes, you are right. Scam Accusations section is better than having Buyers/Sellers Reputation. I don't think many Indians deal on forum and even if they do, Scam Accusation will cover that alongside other kinds of scam. Nice suggestion, proceed and we will support. How are you plannig to propose, via Meta section?


That goes without saying. It doesn't make much sense to generalize topics just because they are written in language other than English. Scam accusations in regional languages should also be posted in Scam Accusation section.

Closed! Already bought required amount. No longer looking for the seller.

Bitcoin is not that big. On ground level, corona pandemic hardly have any significant effect on Bitcoin and cryptocurrency ecosystem. So I doubt that many have actually  transferred their money from cryptocurrencies to more liquid form due to coronavirus. The extensive shrinkage of crypto market last week was entirely speculative in my view. Few sellers panicked and thought pandemic will have impact on cryptocurrencies in coming days so they sold. As a ripple effect which is very common in crypto market, prices continued to fall for next 3-4 days until we hit $3800 (momentarily). After that market stabilized and bounced back to $5000. It remained there for next 2-3 days and finally when traders gained their confidence back in cryptocurrecies, market started responding again since yesterday. Bitcoin alone has grown roughly 30-40% in last 2 days.

I am positive that we will regain Jan-Feb level if nothing chaotic happens in next 10 days.

There are actually two ways you can apply double and add method. You have already mentioned one above i.e. when index is decreasing. However, there is another when index is increasing. The other one from the same Wikipedia (P is generator):


This formula is also starting from index number 0 but my formula is absolutely correct because in first step Q is 0 so point_add(Q,N) will return N. So the return value of Q after first iteration will be N while the return value of N will be double N. In next iteration (when index is 1), the values which will go in point_add will be:

Q ← point_add(N, point_double(N)).

This is similar if we omit first iteration and double N (generator point) before starting the loop.

Now compare with my formula which I posted in other thread (I remember you objected this issue there too):


I hope it is clear now.

I don't understand the last line. You yourself saying that you get salary into bank, there are millions of transactions happening in fiat currencies involving bank everyday. It's clear that Bitcoin can never replace that system because of its limitations. We don't have any other alternative to replace current monetary system. Cryptocurrencies are the closest substitute to money and they are failing when required to be used at large scale. So believe it or not but state owned currency system where you are only offered promise of pay (legal tender) and not full control of currency is the only solution to be used at mass scale for now.  

And another important point. Bank isn't declining you to use your money, it is only declining you to use its service. There's a difference. When you sending money from your bank account to other's account, you are actually using bank's service of remittance. This is interesting point Supreme Court of India mentioned in recent case related to cryptocurrenices:

"It is ironical that virtual currencies which took avatar (according to its creator Satoshi) to kill the demon of a central authority (such as RBI), seek from the very same central authority, access to banking services so that the purpose of the avatar is accomplished."

*RBI is central banking authority in India.

Well, thousands of articles since last several years are telling this and branding Bitcoin as a saviour against crisis. When I read the title, I really liked it because I was expecting this question. People have to realize that Bitcoin is driven by traders psychology, not by some divine force.


I differ a little on this. Bitcoin is not same class of financial assets like stock market or even gold. It is expected from stock market to fall in such condition because traders feel that such pandemic will reduce the profits of companies so they tank the share price in advance. However, bitcoin is different. It is not dependent on the performance of any company or organisation. It is independent and its value depend upon the psychology of holders. It was interesting to see that many investors thought the value of bitcoin was overvalued and they went on to liquidate their holding.

Or can we say Corona has been a blessing in disguise?
I wanted to buy large amount of bitcoin from very long time however my target dip was not coming. But Corona gave me perfect opportunity to make investment. And the best thing about current fall is that it is not catastrophic. It is just speculative and will recover soon.

How can you say buying more bitcoins at a higher price is foolish? I consider buying bitcoin as bargain whatever the price is. I am into Bitcoin since last 5 years and noticed one thing that after every long upward trend, downtrend always follows and after each downtrend, bitcoin recovers its value with time. This cycle is repeating since the day bitcoin trading started. Only exception to this case is humongous rally of December 2017. But I think we will soon see $19K again and once it happens, no one will be foolish anymore according to your definition. Let's not forget HODL.

Hey Siddharth,
Good to see you back on the forum. I want to ask you a question. Can we use INR that we deposit directly on WazirX for P2P purchase? Or those can only be used to purchase in INR sub-section of 'Exchange'.

2

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This was Supreme Court's comment on the lukewarm response of RBI in regards to the freezing of bank account of Koinex by Central Bank of India. Court said that it expected a better response from RBI when RBI replied that it didn't ask Central Bank of India to freeze the account. This shall be enough to figure out how slow and inefficient is the working of RBI. Like every other public institution, RBI is also full of red-tapism. I guess we have to wait more.  

You are absolutely right. Humans have common tendency of greed. They may win one or two times but their greed will drive them to bet more and more and in the end, they lose everything. Generally there are two factors which help fair gambling sites to earn:

(i) House Edge: Suppose a site have house edge of 2% then among 100 bets, roughly 51 will go in the favor of casino while 49 will go in the favor of players. So if each bet worth $100 then casino will make $200 per $10K which are wagered on the site. However, we notice that casinos have much higher profits than 2%. That's because of second factor.

(ii) Players Greed: Even though 49 out of 100 bets go in the favor of players but greed drive players to bet more and more. Suppose I start with $100 and win two games in the row. Now I have $300. But I won't stop here, I will gamble more and it just needed one bet to turn the table. Suppose I increased my bet amount to $150 for third bet and lost! This will further provoke me to go all in for the fourth. And what if I lose the 4th bet? As per the first factor, 2 bets are won by player and 2 are won by house so profit shall be nil. However, greed factor made player to bet everything and lose. Thus house will make the profit of $100 in the end. This scenario happens with 80% players and that's why gambling in profitable business from house's point-of-view even with low house edge.

Ever wonder why it isn't possible to guess private key from bitcoin address? How private key keeps your fund safe? How signatures can only be generated using private key but can be verified using public key? The answer to all these questions is Elliptic Curve Cryptography (ECC). Although ECC is not unique to Bitcoin and was introduced much before Bitcoin but it is one of the most important fundamental of Bitcoin. With just few lines of code, ECC ensures that funds on address remain safe and only person holding private key can access those funds.

Ok! Now let's dive deep into the topic. I will not explain the basics of Elliptic Curve Cryptography in this thread. Rather I will take essential components of ECC which are being used in Bitcoin and only explain things from Bitcoin's point of view so things remain easy to understand.


Bitcoin uses specific elliptic curve known as secp256k1. SECG have defined the exact values for various parameters that are used in the calculation for secp256k1 curve. There are total 6 parameters but we only need 3 for the calculation. Let's have a look at these three parameters first:

P = 2²⁵⁶ - 2³² - 2⁹ - 2⁸ - 2⁷ - 2⁶ - 2⁴ - 1

G = 04 79BE667E F9DCBBAC 55A06295 CE870B07 029BFCDB 2DCE28D9 59F2815B 16F81798 483ADA77 26A3C465 5DA4FBFC 0E1108A8 FD17B448 A6855419 9C47D08F FB10D4B8

n = FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFE BAAEDCE6 AF48A03B BFD25E8C D0364141

These values may be bit confusing for now but let's understand them. P is a very large prime number which is used to calculate mod in the formula.

G is generator point. It has 3 parts:
(i) 04 which shows that point is in uncompressed form.
(ii) Next 64 characters are hexadecimal representation of X-axis of generator point which is when converted into integer looks like this: 55066263022277343669578718895168534326250603453777594175500187360389116729240
(iii) Next 64 characters are hexadecimal representation of Y-axis of generator point which is when converted into integer looks like this: 32670510020758816978083085130507043184471273380659243275938904335757337482424

You may have studied in mathematics that point (2,4) means point is 2 on X-axis and 4 on Y-axis. Something like this:



Similarly G point is nothing but a point on graph with very large coordinates like this:



Lastly, n represents the maximum integer value of private key. Any number between 0 and n is valid private key. n when converted into integer is this number: 115792089237316195423570985008687907852837564279074904382605163141518161494337.


Basically there are three formulas that make up Elliptic Curve Cryptography namely, ECAddition, ECDouble and ECMultiplication. Although we use the terms like addition, double and multiplication but these calculations are not like general addition or multiplication. These are much more complex. As I said earlier, this thread is not about Elliptic Curve Cryptography but how is it used in Bitcoin so I won't explain these formulas and how these are derived. Let's keep this thread simple and understandable.


Now comes the most important and interesting part. How ECC is used in Bitcoin!

This is the system of applying ECC on private key to calculate public key:

1. Convert the hex of private key into Binary representation.
2. Ascertain the number of characters our Binary representation have.
3. Let's say, our Binary representation have 256 characters then we have to apply ECMultiply formula 256 times. ECMultiply involves applying ECDouble on G point and then if the binary character is 1, apply ECAdd formula on the resulting value. Else if binary character is 0, ignore ECAdd and move to next character.
4. Note: We don't have to apply ECAdd formula on the first character even if it is 1.
5. Keep on repeating this and the final point we get after 256 rounds will be our public key.

Confusing? Let's understand this with an example: Since private key can be any number between 0 and n, let's assume 145 as our private key. The hex representation of our private key will be: 0xa8.

Now according to step 1, we have to convert our private key into binary which is: 10010001
Now according to step 2, we have to ascertain the length of our binary which is: 8.
Now according to step 3, we have to do ECMultiply 8 times. Let's do it:

(I am using short form D() for ECDouble and A() for ECAdd)

Round	Starting value	Binary Character	ECDouble	ECAdd	Value going next round
First	G	1	Yes	No (read step 4)	D(G)
Second	D(G)	0	Yes	No (0)	D(D(G))
Third	D(D(G))	0	Yes	No (0)	D(D(D(G)))
Fourth	D(D(D(G)))	1	Yes	Yes (1)	A(D(D(D(D(G)))),G)
Fifth	A(D(D(D(D(G)))),G)	0	Yes	No (0)	D(A(D(D(D(D(G)))),G))
Sixth	D(A(D(D(D(D(G)))),G))	0	Yes	No (0)	D(D(A(D(D(D(D(G)))),G)))
Seventh	D(D(A(D(D(D(D(G)))),G)))	0	Yes	No (0)	D(D(D(A(D(D(D(D(G)))),G))))
Eight	D(D(D(A(D(D(D(D(G)))),G))))	1	Yes	Yes (1)	A(D(D(D(D(A(D(D(D(D(G)))),G))))),G)

So this value: A(D(D(D(D(A(D(D(D(D(G)))),G))))),G) will be a point on graph having two coordinates (X,Y). This point will be our public key which is then converted in Bitcoin Address. D() means we are applying ECDouble formula on the value within brackets while A() means we are applying ECAddition formula on the value within brackets. Note that ECAddition requires two points for the calculcation hence the first point is our result value while the second point is G point.

Wanna see this code in action? Check out my other thread where I have created Bitcoin Address from private key from scratch: https://bitcointalk.org/index.php?topic=5223167.0 . I have provided the complete ECAdd, ECDouble and ECMultiply formula in that thread as Javascript functions. You can learn in depth about these formulas from various online resources and then check their working through my code.


So we have done immense calculation in step 3. But what actually makes this calculation irreversible? Why can't be calculate private key from public key by applying ECDouble and ECAdd in reverse order (afterall we are using G as the input whose value is known to all)? The reason why ECC is so invincible is due to the use of modulus and modulus inverse in ECDouble and ECAddition formulas. So what is modulus (or mod) and modulus inverse (or mod inverse)?

Mod of any two numbers say, mod(14,6) is the remainder obtained after dividing first number with second. For example, when 14 is divided by 6 remainder is 2. So the mod of 14 and 6 is 2. Whereas mod inverse is the number which is when multiplied with first number and then divided by second number leaves the remainder of 1. For example, mod inverse of 3 and 11 is 4 because when 3 multiplied by 4 gives 12 which when divided by 11 leaves the remainder of 1.

ECC uses these two in both ECDouble and ECAdd. So after every round of ECMultiply, we are only taking remainder in next round. We are discarding any quotient obtain in calculation, which makes the reverse calculation almost impossible. For example, even if you know that the remainder is 2 and the number which divided the first number is 6, you can't certainly say that the first number is 14 because it could be 8 or 14 or 20 or so on. In ECC, we uses mod lots of times and on top of that, we are dealing with very large numbers (remember P from Section 1? P is used to calculate mod in ECDouble and ECAdd functions). So virtually it's impossible to do reverse calculation.

I hope this thread made you little more knowledgeable about Bitcoin and why it is one of the best innovation of 21st century. If you already know about ECC and think something in this thread needs to be improved, please let me know, I will make the necessary amendments.

This topic has been moved to Project Development because I (webtricks) think it is more appropriate there. If mods have different view then they can move the thread again to Meta section.

https://bitcointalk.org/index.php?topic=5202297.0

Bump! I have paid for a year hosting+domain so why should this thread bury down in the pages! It deserved to be bumped.  

If you haven't tried it already then try now: https://btctalk.cards . Do share your card in the thread, it would be interesting to see.

Here is my recent basic card:

Hello Guys,
Looking to buy BTC for PayPal. If anyone wants to sell,.please send me your rate in either PM or at Telegram: @webtricky.

They deserve every bit of it. Defending is as much the art as attacking is. It may not look as dashing as scoring goals but conceding only 2 goals out of 11 shots on target (34 goal attempts) is outrageous. This maybe one of the best performance I have seen in recent times. Both central defenders, Oblak, Thomas, Lodi, Koke, Saul and especially Lorrente deserved every bit of this win.

By the way, I already got 3 out of 4 results correct. Round of 16 is turning to be really profitable and lucky for me.

Yeah! That's so unfair from UEFA 
With matches of such caliber, it's shame that both will be played at the same time. I tried watching two games side-by-side during first leg but it was complete mess. So this time I will just watch PSG match. Can't miss Neymar performance in Champions League. Fit Neymar playing his best game is rare sight these days.


Haha evil you! I still can't forget the shocked face of Neymar when Rashford scored penalty last year. I really hope PSG qualifies for quarter finals this year. But Borussia with its young force is no less.


I don't think Atletico will just sit and defend. I still remember how their defensive tactic failed last year when Ronaldo and Co. ripped their defense off by playing cross balls from midfield. Atletico defended good for first few minutes but soon Ronaldo found the way between defenders and headed two goals.


If we talk about few recent games then Liverpool's performance is far from convincing. They have conceded 10 goals in their last 5 games while scoring only 3!
Also let's not forget that Alisson is not playing tonight. Can Adrian with his shaky hands take Liverpool to the quarters? It would be interesting to see.

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LoL! No matter where you live, we all have to wait for 3 hours for match to start. 

What's making you angry? As far as I can read, article shared by OP is supporting PoW (not criticizing it).

Also your math for finding profitability is not including the energy consumed by those miners who tried but couldn't find the block. Only single miner is able to receive block reward+fees, all others waste resources for nothing. Moreover, the fiat value of block reward also acts a determinant for deciding if PoW is efficient system or not because electricity is valued and charged in fiat currencies in every country. The cost of electricity has already made bitcoin mining unfeasible in many countries.

Strange predictions!

For the first game, Leipzig is clear winner for me. I agree that they had a tasteless draw against Wolfsburg but Timo was on the bench for 2/3rd of the game. We have to agree that he is the game changer for Leipzig, all their tactics revolve around him. And it's Champions League we are talking about! Leipzig won't leave any force to beat limbless Tottenham. I predict 3-0 win for RB.

Second game, I agree Atalanta is on beast mode. They have already scored 70 goals in league! Only Bayern Munich and PSG have scored more in top 5 leagues so far this season. But Valencia is unbeaten at home this season. No team has been able to beat them at home (not even Barcelona). It will be interesting match to see. Being a LaLiga admirer, I will be supporting Valencia for this fixture. Let's see if they can bridge the deficit of 3 goals or not.