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1  Bitcoin / Bitcoin Discussion / Giving bitcoins as a gift? on: April 07, 2021, 01:36:41 PM

I have been thinking...
Would it be totally crazy, if I gave 10-15 bitcoins to a woman, who helped me in a really really big way when I was younger.

I mean, would she think I was crazy if I do it?
Would it be a positive thing? Or just weird?

The coins were not worth much when I got them, so from that perspective, it's not THAT big a deal, right?

I would gladly give them to her, but I fear it could have a negative effect to what little friendship we have

And she is married with kids, so while I will always like her, there is no hidden agenda on my part here.   

2  Bitcoin / Bitcoin Discussion / Made my first payment with bitpay :D on: December 09, 2020, 01:24:15 PM
Bitcoin has come a long way.
Yesterday I made my first payment using bitpay and electrum. It was surprisingly easy.
Easy enough for any normal non-technical person to be able to do the same.

The only drawback was that the fee was automatically set to be quite high: 72 sat/byte, when 10 say/byte would have confirmed in approximately one hour. And still it took more than 30min to confirm.


And the remaining BTC in my address are still worth more than what I paid for them. Even though I have used parts of them several times already.
 Grin
3  Economy / Speculation / What. Bitcoin price dropped to 24/BTC on: July 02, 2019, 02:12:17 PM
What happened:

I am usually following bitcoin price from here:
https://www.coindesk.com/price/bitcoin

And now it shows the price to be 24

Did Satoshi sell his coins or did someone break bitcoin crypto?

 Grin

I guess I want to buy more with that price Huh
4  Economy / Games and rounds / One testnet coin giveaway on: June 06, 2019, 12:34:23 PM
Cleaning my computer, and found a testnet private key with 1BTC in it.
If anyone wants to put it back to circulation or return it to a faucet, feel free to do it Smiley

Bitcoin Address: (testnet)
mvwXQY1FAm9BsVdUZ7YaZhpCBnJwT17D5v
Private Key:
cVn8F12YJtKAUNCiUAbzW3PxpGPxxP6yiiwYN1mHh2dmuK8XdVZ2

Have fun playing with testnet coins

I would return it to a faucet, but I don't have an installed testnet wallet.

 
5  Bitcoin / Development & Technical Discussion / On safety of ECDLP used in Bitcoin on: May 10, 2018, 01:25:35 PM
I recently reviewed an interesting work about solving ECDLP  (that Bitcoin uses too.)

Most people think we will need a quantum computer(QC) for cracking ECC, but I am not so sure about it anymore. Conventional methods may prove to be good enough.

Bitcoin uses "Elliptic Curve Discrete Logarithm Problem" (ECDLP). But why is it called Discrete Logarithm Problem? It has nothing to do with DLP. Apparently someone thought that ECC would sound COOLER and SAFER if it is called DLP! And hence the DLP.

In DLP we try to solve x in equations like this: 6^x ≡ 8 mod 11. It is hard (with big numbers) because 6^x can get quite big, many times bigger than the (mod 11) and you will have to subtract 11 many many times.
eg. 6^7= 279936 =8 mod 11. That makes it hard to "guess" x and you will have to try different x values to find the correct one.

In the case of ECDLP we go from 1 to the private key and NEVER go over the order n of the curve.

So basically we try to solve x (x=private key) from  x*G=P , where G is point representing 1 in this system and P is the public key point, and x is always between 1 and n.

The possible weakness comes from the fact that we NEVER go over the order n of the curve. Unlike in DLP, which goes over the "order" (=11 in the example above) many many many times.

Because we always stay between 1 and n, we are not really dealing with DLP and some possibilities arise.

Odd or even. If we can reliably know if a point is odd or even, we can also break ECC.
One point about Finite fields is that they do NOT hide if a number is odd or even.
For example. Finite field of 11 points.

0,1,2,3,4,5,6,7,8,9,10,0,1,2,3,4,5,6,7,8...

If we ALWAYS stay in the first "round" of the field 0-10 (like we do in ECC) the numbers are as they are. 1,3,5,7,9 are odd, 2,4,6,8,10 are even.
So even if odd and even are not really defined inside finite fields, when we stay in the first "round", then odd and even work like they do in the real world.
If we go to the second "round" then odd and even would flip around. eg. odd number 13=13 mod 11=2 which "looks" like an even number. But we never go there, because we are actually not dealing with a DLP problem.  

Luckily for the safety of Bitcoin, Bitcoin uses coordinate points instead of numbers.
Finding out if a point is odd or even is hard. How can you define if a point (8,19) is odd or even? Can it be done?

If you divide the point by 2 it will of-course behave differently depending on if the point is odd or even, but since the result is symmetrical this wont lead very far.

But the conclusion was that they did not get it to work, and ECC is still safe. FOR NOW.

Wonder if this kind of work is the reason NSA stopped recommending ECC.
6  Bitcoin / Bitcoin Discussion / Two blocks mined with only 2 seconds apart! on: December 17, 2017, 02:47:16 PM
Wow.
This has to be a new record?

Blocks 499795 and 499796 were mined with only 2 seconds between them !
Is the difficulty level too low?

https://blockchain.info/block/0000000000000000009df979d54bbe255d33ede8a17f7cf1640eb0c88b0396aa
https://blockchain.info/block/00000000000000000004ed5101af30d1a64d2c1ddd13324c8fae3507792141ad

7  Bitcoin / Development & Technical Discussion / Creating private key from 2 different RNG:s? on: October 12, 2017, 12:39:55 PM
Is it safer to use 2 different random number generators in generating a secure private key?

If your RNG is truly random then that is excellent, and you do not need anything else in generating your private key. But how can you know?

If you suspect that one or the other RNG is perhaps not truly random, or that it might be somehow compromised, wouldn't it be a good idea to generate 2 private keys in different ways, and then XOR them together to get one that is really random?

I am planning to use bitaddress.org and urandom()  (=operating system RNG) to get 2 256bit random numbers and then XOR them together.

The problem with bittaddress.org is that it is someone else's code. I do not know if there is a bag-door/vulnerability in it. I do know bittaddress.org is well trusted, but what if a hacker has just changed the code in the web-page?
Problem with urandom() is that when it has enough entropy it is a good RNG, but if it doesn't have enough entropy, then it can give insecure random numbers. And you can not know., because urandom() does not tell you if entropy is low.

In my opinion combining these 2 by using XOR should give reliable private key even if one of the RNG:s is not as random as it should.

Opinions?
8  Bitcoin / Development & Technical Discussion / Is reusing addresses safer? on: October 06, 2017, 10:53:02 AM
For each bitcoin address, there exists about 2^96=79228162514264337593543950336 private keys, that generate the same address.

And any of those private keys can be used to send coins from that address.

My question is: If one key has already been used to send from an address, can the other private keys still be used to send from the same address?

Or does the blockchain check what private key has already been used, and accept only the payments signed with that private key?

Accepting only the key that has already been used, would increase security. Since it is much more difficult to find 1 key than any of 2^96 keys.
(both cases are of course extremely unlikely, but the second case is still 2^96 times more likely)

If only one private key is valid, then an address, that has a send action is safer than an address that does not have a send action. And reusing an address is the safest choice. (at-least before quantum computers)

How is it? The wiki is not clear about this.
9  Bitcoin / Development & Technical Discussion / MOVED: Bitcoin address holding $$ not BTC ? on: October 06, 2017, 09:20:47 AM
This topic has been moved to Bitcoin Discussion.
This belongs better to bitcoin discussion, nothing technical here.
https://bitcointalk.org/index.php?topic=2239320.0
10  Bitcoin / Bitcoin Discussion / Bitcoin address holding $$ not BTC ? on: October 05, 2017, 12:34:11 PM
How is it possible that some addresses have dollars in them instead of bitcoins?
Example here:
https://blockchain.info/address/37X5mtn38nHj9ZtDeyZKfvwWjjuguNdvgK
And dollar transaction:
https://blockchain.info/tx/1269e5050787fc26d49f619c1a1ca1446fd4ba2789c2c5865dd9853ec471eeef

Can I now convert BTC directly to digital dollars? How is it done?   Grin Cheesy
11  Bitcoin / Development & Technical Discussion / Error in blockchain ? on: October 01, 2017, 01:14:41 PM
Or maybe a bug in block-explorers ?

This address: "16va6NxJrMGe5d2LP6wUzuVnzBBoKQZKom"
Has different amounts of bitcoins in different block-explorers!
How can it be possible?

blockchani.info says it has 50BTC
https://blockchain.info/address/16va6NxJrMGe5d2LP6wUzuVnzBBoKQZKom
bitinfocharts shows 100BTC
https://bitinfocharts.com/bitcoin/address/16va6NxJrMGe5d2LP6wUzuVnzBBoKQZKom
and blockexplorer shows 0.00050026BTC
https://blockexplorer.com/address/16va6NxJrMGe5d2LP6wUzuVnzBBoKQZKom

What is going on in here?

Personally I think 100 BTC shown by bitinfocharts is the correct one. Could anyone running a full node check what address: "16va6NxJrMGe5d2LP6wUzuVnzBBoKQZKom" has in it?
12  Bitcoin / Development & Technical Discussion / We need a light version of Bitcoin Core on: September 17, 2017, 01:54:15 PM
Running bitcoin core, requires:  

  • Downloading over 120 Gb of data
  • Verifying every transaction ever made
  • Waiting for a very long time (for it to finish)  

Doing all that just for wanting to run your own wallet in bitcoin core seems like overkill.
And it is only going to get worse as time goes on. After ~5 more years the blockchain will probably be >300Gb

I think it would be a GREAT idea to create a lighter version of Bitcoin core. "Bitcoin Core Mini"
It could be done, because for creating and verifying new transactions you do not need to have a full copy of the whole blockchain. All you really need is the info about all bitcoin addresses, that contain any bitcoins, and the inputs to those addresses.
The old transactions do not really matter for the purpose of creating and verifying new transactions.

For running "Bitcoin Core Mini" you would need
the balance and inputs of every address containing bitcoins, Eg. from today when blockchain was at block  #485732

For this info it would be enough to download a signed, trusted file of about 10Gb, and then verifying every transaction that has happened since the file was created eg. at block #485732
(New ~10Gb file could be made accessible every year or 6 months)
 
Estimated size of the file comes from:
10000000           Addresses with balance
          * 1 kb       for info of the address (inputs, outputs balance.)
                          Some addresses would need more than 1kb, some less
10000000 kb                          
            =
          10 Gb

The size of the file could be made a lot smaller, if we forget the "dust addresses", that contain only a few satochis, and are unlikely to ever be used. In those cases we could just have a list of those addresses without any additional info. (it would take minimum amount of space)  And if any of those addresses would ever be used, the "Bitcoin Core Mini" would then ask the needed info from the network, from a full node.

Anyone interested?
With "Bitcoin Core Mini" you would get almost all the advantages of a full Bitcoin Core. You could create and transmit your own transactions but you would not need to download and store over 120GB of data.
In the long run the size difference would only be getting bigger. In the future,  when the blockchain size will be  >500Gb, the Mini version would probably still remain under 20Gb  

Who would want to run "Bitcoin Core Mini" (if it is made)?
Would anyone want to be part of developing it?

I might be interested in developing it, if there is enough interest. Maintaining it in the long run is another thing.
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