Gold collapsing. Bitcoin UP.

dontcensormebro2

New Member
Feb 2, 2018
2
9
Hey everyone, my friend and I will be attending satoshivision. Check same username for verification on reddit (and this is my second user (a completely different username, not the unnumbered version of my current one), somehow i abandoned my main because it was banned in rbitcoin so long ago). Would love to meet up with some of the people I grew up on (the real BCH) bitcoin with! We arrive the 21st and leave the 28th. Leaving some extra time around the conference to do some exploring. Would be awesome to meet up and grab some drinks or whatever. Let me know!
 

Dusty

Active Member
Mar 14, 2016
362
1,172
b) Yes, ff you could prove, that SHA256 was injective I'd guess you could easily invert it.
Exponentiation in Zp, when you use a generator as base, is an injective function, i.e. you can generate all the elements of the field by changing the input (the exponent).
But doing the inverse is the impossible to crack problem of discrete logarithms that makes ECDSA work, so I don't think that statement is true.

In the case of SHA256 of course you can't have an injective function because the codomain has 2^256 elements while the domain is arbitrary.
 

Zarathustra

Well-Known Member
Aug 28, 2015
1,439
3,797
It's really unbelievable. TA genius @masterluc, aka PentarhUdi painted this in August:

https://www.tradingview.com/chart/BTCUSD/3RjQGYZp-No-resistance-till-15000-when-3500-will-break-up/

He isn't active on tradingview anymore. This is his today's post on VK.com:

https://vk.com/bitcoin_vanga?w=wall-130254204_8317

Correction more or less over. Elliott wave 5 goes to 100K.

Difficult to believe. That would mean that either BTC will implement a scaling solution, or we have to expect an even bigger wave of irrational exuberance on the non-Cash chain. Or wave 5 includes the total value of both forks.

 
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79b79aa8

Well-Known Member
Sep 22, 2015
1,031
3,440
LN would be too late with too few use cases if it existed.

meanwhile, transactions with bitcoin cash hit the network in seconds. after an hour they become irreversible, making bitcoin cash a secure and direct way for parties to transfer any amount of money.
 
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dontcensormebro2

New Member
Feb 2, 2018
2
9
I can confirm that @dontcensormebro2 is the same person as, uh, himself on Reddit. Welcome!
yes sir, i confirmed the pm on reddit with simply “confirmed”. i would love to meet up with everyone in tokyo, so any invite to a private get together would be awesome. i will spend some time over here and contribute when i can. as for who i am, just an enthusiast supporting the bitcoin whitepaper and onchain scaling as satoshi intended. cheers!
 
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Dusty

Active Member
Mar 14, 2016
362
1,172
meanwhile, transactions with bitcoin cash hit the network in seconds. after an hour they become irreversible, making bitcoin cash a secure and direct way for parties to transfer any amount of money
I wouldn't be so sure of that: BCH has a tiny hashrate compared to BTC and someone could borrow a few pools to easily rewrite even long parts of the Bitcoin Cash blockchain.
Rewriting the latest 10 blocks or even more should be quite possible with a (relatively speaking) modest amount of money.

So I suggest you to wait at least 12-20 confirmation for big sums of money transferred with Bitcoin Cash.
 

freetrader

Moderator
Staff member
Dec 16, 2015
2,806
6,088
@Dusty : I can't help but feeling that your assessment of the chances of a 10-block rewrite are bit unrealistic.

https://bitinfocharts.com/

Bitcoin Cash (BCH) hashrate at ~2.5Eh/s is currently around 1/8 of BTC. That's not really "tiny"!

This could of course change... but to rewrite 10 blocks successfully you'd need to wait quite a long time unless you have significantly more hashpower than the overt BCH network.

To "borrow a few pools" to rewrite 10 blocks on BCH, you need to produce significantly more than 51% of its hashrate. If you can have 51% your chance of eventual rewrite even of 10 blocks is guaranteed, but the closer the hashrate ratio the longer it will take and others will notice.

So you would need to overwhelm the honest BCH miners with a hashrate multiple times theirs, to pull it off fast. But here's the rub :

The set of BCH honest miners are likely from a subset of BTC honest miners which control ~50% of BTC hashrate (or more). We have seen this in the past when BCH mining hashrate equalized with BTC hashrate during times of "crisis" (times where hard fork upgrades needed to be secured/defended), such as around Nov 13 hardfork.

https://bitinfocharts.com/comparison/hashrate-btc-bch.html#6m

It's rational to assume that once a 51% attack on BCH is detected, the honest BTC miners will again defend, and there is no way to secure an overwhelming hashrate majority against them.

This is why I'm confident that a 51% / chain rewrite attack is purely hypothetical given today's Bitcoin / Bitcoin Cash mining relations.

https://bitcoil.co.il/Doublespend.pdf
 

Justus Ranvier

Active Member
Aug 28, 2015
875
3,746
Rewriting blocks has a cost that can be calculated, regardless of how "honest" you assume miners to be. It is the opportunity cost of not extending the chain.

Percentages of hash rate don't affect this cost - even a hypothetical miner with 100% hash power will forfeit revenue by rewriting an existing block rather than extending the chain.

So an easy first order approximation is divide the number of bitcoins you're sending by the block reward and wait that many blocks if you want a guarantee that anyone rewriting blocks to defraud you will lose money.
 

satoshis_sockpuppet

Active Member
Feb 22, 2016
776
3,312
Three doomsday scenarios for Bitcoin:
https://www.rt.com/business/417772-bitcoin-doomsday-scenario-collapse/

Not an intersting "article" by any means.. But:
The reason why bitcoin cash and other spin-offs split from bitcoin is that the original cryptocurrency lacks capacity. Bitcoin's one megabyte file size for transactions can process nearly 2,500 transactions per block on blockchain. Bitcoin cash is eight megabytes and is much faster.
It's interesting to see, that they don't mention Ethereum or Ripple or any other Altcoin but Bitcoin Cash. (And other spin-offs.. Like Bitcoin Gold? :D )
 

freetrader

Moderator
Staff member
Dec 16, 2015
2,806
6,088
@Dusty : No worries, I realized (after Justin's reply) that I also went on a tangent because the original commenter to whom you replied stated "any amount" and it definitely doesn't make sense to take such risks for large amounts.

I greatly appreciate Justin's first order approximation, and apologize since I was too lazy to produce a graph of expected number of blocks it would take to win the double-spend rate at 10 confs at given hashrates. I think this was already done in this thread prior to the Cash hardfork, when people calculated the expected costs of > 51% attacks on the chain.
 

79b79aa8

Well-Known Member
Sep 22, 2015
1,031
3,440
i love it how you guys will not put up with hyperbole.

gosh, i guess i'll need to wait around half a day to feel safe my million dollar transfer will not be double spent. or maybe i'll split it in a few chunks, it' not like transactions are costing me 2 cents or anything.

i predict in 5 years the story of how "the original bitcoin got overtaken" will be conventional wisdom among MBA types (and in 10 years generally). it will be obvious in hindsight, but most of the ones who will say it smugly are nowhere to be seen now.