I'm not sure if such an approach would really make double spend attempts futile though. It discourages double spending, yes, but gives no solution on how to resolve conflicting transactions, should they occur. Also the discouragement only works insofar as that the network tries to punish the double spender by enabling other network participants to attempt double spends of their own.

The problem being as follows: In essence revealing the private key on attempting a double spend only means that other network participants can now double spend your coins as well. Which means it now boils down to who spams the network the hardest to force the double spent. Tough luck for someone double spending by accident; a field day for an adversary that attempts a double spend on purpose and has a botnet at their disposal. And that's ignoring the question of resolving conflicting transactions as mentioned above.

You mean randomly assigned block rewards to full nodes that don't mine or mine very little? Possibly based on the IP address of said node?

Opens up the possibility of sybill attacks (ie. manipulating the "vote" for each valid block by pretending you are multiple nodes) and wouldn't give users from developing countries a better shot at it.

Merely running a node is comparably cheap. If a block reward were tied to the number of nodes you have online (ie. the more nodes you hold, the higher your chance to get randomly chosen), you'd simply have people spinning up thousands of virtual machines. Or worse, you'd have ISPs and state actors take over, as those have access to the largest pools of IP addresses.

About that: Bitcoin addresses contain a checksum; which means that changing a single letter will usually lead to an invalid address -- unless you're really unlucky, that is. Or have a sucky wallet that for some reason doesn't check for validity. This may look different with alts however (eg. Ethereum addresses don't contain a checksum by default if I recall correctly).

It is also worth noting that while malware could just change parts of the address, the chance that they happen to have the private key to a sufficiently similar address is rather small (see the computational power required for generating vanity addresses). So unless an adversary knows which address you are going to use next and spends significant effort into trying to generate a similar address, it is usually sufficient to just check parts of the address.

That being said, the more paranoid the better, especially if larger sums are involved.

I think I get the gist of what you are trying to say, but note that "permissioned" vs "permissionless" in the context of blockchains usually means something different: Permissionless means that no single entity can prevent anyone else from sending a transaction. Permissioned means that there are central entities that have the power to prevent certain transactions from being settled. I might be wrong, but I think the concept you are referring to is "trustless" vs "trusted". In both cases it's silly to apply the concept of permissionlessness and trustlessness to centrally controlled ledgers though, with that I fully concur.



SEPA and SWIFT are not pseudonimous. There are central lookup tables, otherwise banks wouldn't know where to send the money. No such thing with cryptocurrencies, not even the centralized ones.

That is indeed the biggest problem right now. I do assume that exchanges will get their shit together once Quantum computers get feasible in a big scale, but on the other hand there have been exchanges that didn't even do transaction batching until just recently. At least in theory it shouldn't be that hard to avoid address reuse though, even at the scale of nowadays exchanges.



Bullshit and misinformation. Quantum computing will be able to solve some math problems faster than traditional architectures, that still doesn't make them a magic devices that instantly derive private keys from public keys or can "break the chain of today supercomputer in fraction of seconds" whatever that may mean.

Also the article shows complete misunderstanding of how mining works:


More efficient miners won't lead to a reduction of electricity consumption -- it will only lead to more miners, offsetting whatever electricity savings have been made.



Oh definitely. I'm not saying that quantum computing is bound to come into fruition, I'm just saying that the same physical limits (ie. size) that affect traditional architectures don't affect quantum computers -- pretty much by definition.



Candidates for quantum resistant cryptography already exist, it's mostly a matter of standardization and deployment. The latter possibly being the largest challenge.

Where did you read that? Reddit's official stance since the beginning was that they disabled Bitcoin payments due to issues with Coinbase, not due the speculative nature of the market:
https://www.bloomberg.com/news/articles/2018-03-28/crypto-community-hub-reddit-disables-bitcoin-payments

Reddit has been on the forefront of accepting Bitcoin even before the bubbles of 2013, so it'd be kinda weird to assume that they start deeming it to be too volatile just now.

Here's one of my favourite introduction into the fundamentals of cryptocurrencies, the problems they are trying to solve and the context out of which Bitcoin's approach arose:
https://cacm.acm.org/magazines/2017/12/223058-bitcoins-academic-pedigree/fulltext

Especially the reference section may be of interest to you, as it includes a lot of further reading regarding both the current state of cryptocurrencies and some of the fundamental research that preceded it.

@OP: Solid advice.

One thing to add: Be aware of malware that changes copy / pasted crypto addresses on the fly. When copy / pasting addresses from or to your (hardware) wallet, always double check. If a higher amount is at stake, check via a secondary channel as well (eg. confirmation email on another device). While hardware wallets protect your private keys, they can't prevent you from phishing-like attacks such as that.



Coins supported by Trezor:
https://doc.satoshilabs.com/trezor-faq/overview.html

Coins supported by Ledger:
https://www.ledgerwallet.com/cryptocurrencies



This can't be stressed enough. Do not buy hardware wallets from the likes of Amazon or eBay resellers.



Trezor wallets only supports ERC20 tokens so far as they only support ETH and ETC in terms of tokenizable cryptocurrencies.

Ledger seems to support NEP-5 / NEO tokens as well. With most of the other alts that Ledger supports I'm not all that familiar.

That's its IP address within your local network (ie. the connection between your PC and the router). The public facing IP address (ie. the address that a website sees when you are visiting it -- or a node connecting to your node, for that matter) is a different address and provided to you by your ISP.

Depending on your ISP and router setup this may be an old school IPv4 address (like 192.168.1.254) or a shiny new IPv6 address (like 0:0:0:0:0:0:0:0 just with actual values instead of zeroes).

As mentioned above, the required computation power for securing a blockchain has nothing to do with its transaction throughput. You should really do more research on what PoW actually does in the context of cryptocurrencies before jumping to the faulty conclusion that it directly correlates to transaction throughput and scalability.

What happens when you google "what is my IP"? Do you get an IPv4 address such as x.x.x.x (x ranging from 0 to 255) or an IPv6 address such as x:x:x:x:x:x:x:x (x ranging from 0000 to FFFF)?

Because in the LN block explorer your unknown IP address is shown in the IPv6 format. Maybe your router is set up to support IPv6 by default and the lightning node client (or the acinq block explorer) is not able to properly handle it?

The first step, getting a handful of qubits into a stable position, is already done:
https://newsroom.intel.com/news/intel-advances-quantum-neuromorphic-computing-research/
https://www.technologyreview.com/s/610274/google-thinks-its-close-to-quantum-supremacy-heres-what-that-really-means/

It's a long shot from production ready quantum computing, but there's a reason why NIST is already working on a new standard recommendation for post-quantum cryptography:
https://csrc.nist.gov/Projects/Post-Quantum-Cryptography

It's not around the corner, but we're well on our way. It is worth noting though that quantum computing is not the magic wand that it is often made out to be.



Traditional computing reaching its physical limit is actually one of the reasons why quantum computing is being heavily researched in the first place. Accordingly we can expect more and more funding being poored into R&D for quantum computing (and other approaches such as neuromorphic computing) as improving traditional architectures becomes less and less feasible.


That is assuming brute-forcing the private key space of Bitcoin. Quantum computing could make deriving the private key of an address from its public key actually feasible.

You know how Bitcoin is sometimes described as being protected by math? There are math problems at which quantum computing stands to excel compared to traditional computing -- some of which will likely affect asymmetric cryptography as used by Bitcoin.


If you are referring to sociopolitical threats -- yes, definitely.

So far it seems like quantum computing will only affect a certain subclass of asymmetric, ie. private / public key cryptography. This means it will become significantly easier to derive private keys from known public keys, which does indeed put bitcoins at risk.

However the public key of a Bitcoin address is not known until the first outgoing transaction is made. Generating a Bitcoin address from a public key involves hashing the key using SHA-256 which is assumed to be fairly quantum-resistant, making your coins save as long as you refrain from reusing addresses -- which, incidentally, is also how Bitcoin is supposed to be used.

That is assuming Bitcoin won't be updated accordingly. I'm fairly confident that Bitcoin will evolve as new security threats arise.



Regardless of to whom quantum computing will be available, it will still necessitate to upgrade pretty much all of the internet. A daunting task; quantum computers won't help with that.



The richest addresses are owned by some of the largest exchanges:

https://bitinfocharts.com/top-100-richest-bitcoin-addresses.html


So if one of these piñatas gets cracked a lot of people will get a haircut. I do assume that exchanges will change their address usage policies once quantum attacks are at the verge of becoming feasible.

What exactly do you mean -- that you sent the LN channel opening transaction with too small a fee?

As far as transaction accelerators are concerned, there's the one by ViaBTC:
https://pool.viabtc.com/tools/txaccelerator/

The free service requires a certain minimum fee to be present, but they also offer a paid service where no such requirement exists. I've only used their free service so far, so I can't vouch for their paid service however.



I too wonder where this misconception comes from. By now it should have become fairly clear that you are your own node operator and that the other nodes along the route have no way of targetting specific transactions.

That's not good, I'm afraid you've become the victim of a malware attack. Always double check addresses between copy / pasting as there's malware out there that will change copied Bitcoin addresses on the fly before it gets pasted into another input field. While hardware wallets protect your private key, it can not prevent those kind of attacks which still require an additional level of vigilance on your side.

Did you try copy pasting Bitcoin addresses, as suggested by bob123, to confirm our suspicions? Copy / paste another BTC address from your ledger into the address field of your browser or the forum's message field. Check if it's the same address as displayed by your Nano S.

Did you buy the Nano S directly from ledgerwallet.com or did you use another reseller? (eg. Amazon, eBay)

What did you do exactly?

I'm guessing your steps, and you just tell me whether I'm right:

1) You copied the address given by your Nano S into the Coinbase withdrawal field

2) You withdrew money from Coinbase to the copy / pasted address

3) You noticed that your Nano S doesn't recognize the address and doesn't receive the coins

4) You check the address that you withdraw to on Blockchain.info

5) You scan the QR code on Blockchain.info with the Blockchain.info app and it shows the balance in there

Yes / no?

If your answer is yes, there's a high chance that your system is infected with clipboard malware, as suggested by bob123. In this case try copy / pasting a Bitcoin address into a txt file as suggested by him and check whether the Bitcoin address that gets pasted into the txt file is the same as the one you copied. If the pasted address is different from the one you copied: My condolences, your coins are lost, your computer is infected, reinstall your operating system and change all your passwords.



It's not processing. Watch-only means that you can only check the balance of this address but not send any money from it.

To be honest: A cautious player won't trust you more because you provide them with the private keys to their deposit address, especially knowing that you store a copy of the private key on your own server anyway. If anything it opens up additional attack vectors for hackers and puts the balances of your players at risk. To make matters worse, even without a hacker attack any player could move their own coins and then throw scam accusations at you for not keeping their coins save. There's no way to solve such a dispute (ie. whether you stole the coins or whether the player moved the coins themselves).


Short of falling back on some of the less widely used alts I'm afraid you'll only have two choices:

a) Accept payments directly on a cold storage address and keep track of in-game moneyflow on an internal database, off-chain. This will require the trust and goodwill of your player, but as mentioned above: Even providing the private key to their deposit address won't replace trust.

b) Become a bleeding edge pioneer and start accepting LN micro transactions. (YOLO!)
https://medium.com/@ismailakkila/bitcoin-setup-your-own-lightning-node-on-mainnet-94337bda09fa

It wasn't part of the original proposal, but it's mentioned in this Lightning Labs presentation, for example:
https://cyber.stanford.edu/sites/default/files/olaoluwaosuntokun.pdf

Apparently the idea was first brought up here:
https://lists.linuxfoundation.org/pipermail/lightning-dev/2015-July/000019.html

ProfessorZ is not wrong though. Or rather, it's a question of semantics.

On one hand you could define a blockchain as the canonical transaction history of a cryptocurrency. In this case it is indeed only as immutable as the consensus algorithm is secure -- both in quality (eg. PoW vs other proof-of-resource schemes) and quantity (amount of work put into the chain).

On the other hand you can view PoW as a consensus mechanism that selects one blockchain as the canonical one amongst many, the other ending up as chain splits and orphans. In this case each blockchain is indeed immutable, it's just that only one gets to write history -- literally.

I think both perspectives are valid and highlight different ways to look at consensus. Regardless of that it shows how difficult it is to meaningfully decouple blockchain as a data-structure from its consensus algorithm -- both technically and conceptually -- which is probably why so many blockchain-the-technology projects seem to lack in substance.

Technically speaking, a blockchain is really just that: A chain of blocks that builds block upon block, as to provide a gapless, immutable (transaction) history. So in the narrowest sense of the term it really is just that: A data format, a type of ledger.

Whether a blockchain is secured by PoW, PoS, some other Proof-of-Resource or a different consensus algorithm altogether is a different question.

A blockchain does not necessarily use PoW. PoW does not necessarily apply to blockchains only. The data structure itself (eg. blockchain) is a separate component from the consensus algorithm (eg. PoW).


That being said, you point out a very important aspect of this whole matter: That consensus is key.

The blockchain as a data-structure is a rather boring matter. The consensus algorithm (ie. PoW in the case of Bitcoin) is where things get interesting. It's the heart of the matter, enabling blockchains to provide secure, trustless and permissionless (monetary) transactions.

However PoW is a weird solution to a hard problem. It's not an easy sell. And companies in general don't care about trustlessness or permissionlessness -- quite the opposite actually, as it's a liability both legally and economically. There's more money in building walled gardens, rather than open ecosystems. Hence the focus on blockchain, rather than the consensus algorithm. Hence the focus on DLT, whatever that may be.