As much as I love the idea I doubt that many people will follow through. People have been told time and again to not leave coins on exchanges except for trading purposes, yet this warning is rarely heeded. I think the only ones that actually would follow through, are the ones that don't have their coins on exchanges to begin with.

Either way, if even just a few more people end up with holding their own private keys, that'd already be a net positive.



Shhh, no spoilers!

Slimmer than getting infected by some crypto-stealing malware or falling for some phishing site.

If you're worried about the safety of your coins, do yourself a favour and either get yourself a hardware wallet or set up a dedicated offline device for cold storage. You'll sleep better.

Yes. Bruteforcing being the only known way to find the original input (in this case: the public key).



I wouldn't say "totally impossible", but right now we have absolutely no reason to believe that a quantum computer would be better at this task than a classical computer.

Note that the theory of quantum computing far precedes it's practical implementation so it's fairly well understood. Accordingly it's rather unlikely that a surprise solution breaking those specific cryptographic hashes will come out of nowhere.

What do you mean by "why"?


Technically because we're talking about two completely different types of cryptography.

One is asymetric cryptography:
https://en.wikipedia.org/wiki/Public-key_cryptography

The other are cryptographic hashes:
https://en.wikipedia.org/wiki/Cryptographic_hash_function

Note that a weakness to quantum computing is neither inherent to asymetric cryptography nor to cryptographic hashes. Not all private / public key schemes are necessarily at risk and not all cryptographic hash functions are necessarily quantum resistant. There's a lot of cryptographic algorithms for either type of cryptography, based on different kinds of math problems; some for which quantum computing will provide little to no speed-up.


In terms of what satoshi intended -- who knows? The quantum algorithms in question have been developed in the 90s so it might well be that satoshi anticipated a possible quantum threat in the future.



*without knowing the public key, yes. At least according to our current understanding of mathematics.

I presume OP has been using Electrum's page of previous releases:
https://download.electrum.org/

At least I hope so. OP, if you haven't checked the APKs from the link above yet, do so. If you've tried an APK from a third-party website... consider wiping your device and doing a factory reset before installing a new wallet.



That is post is already 4 years old though and as of today Mycelium only supports Android 4.4 and up:

https://play.google.com/store/apps/details?id=com.mycelium.wallet

(at least officially, maybe you can still get it to work with older Android versions).

Oh quantum computing is already here. Matter of fact, you can have some fun with quantum computing today:

https://quantumexperience.ng.bluemix.net/qx/experience

It's just that it still has a long way to go before any of the currently known algorithms can be applied to cryptography in practice. To give some perspective, breaking ECDSA as used by Bitcoin is expected to require thousands of qubits [1][2]. Currently we're at the tens of qubits [3] (ignoring D-Wave quantum computers which follow a fairly different approach that isn't applicable to the sort of math problem that ECDSA poses [4]).

[1] https://security.stackexchange.com/questions/87345/how-many-qubits-are-needed-to-factor-2048-bit-rsa-keys-on-a-quantum-computer
[2] https://en.wikipedia.org/wiki/Elliptic-curve_cryptography#Quantum_computing_attacks
[3] https://www.quora.com/How-many-qubits-does-the-current-state-of-the-art-quantum-computer-have
[4] https://crypto.stackexchange.com/questions/40893/can-or-can-not-d-waves-quantum-computers-use-shors-and-grovers-algorithm-to-f



Deriving (a) the private key from a public key is a completely different operation from (b) bruteforcing the public key from its nested cryptographic hashes. While (a) may become feasible with quantum computing eventually, (b) appears to be infeasible even for quantum computers.



Capable of trying maybe, but not capable of succeeding.

If you'd try to brute force the Bitcoin address space -- and brute forcing is all you could do, given that there's currently neither a way to derive a private key from a public key nor a way to derive a public key from a BTC address -- you'll be engulfed by the sun turning into a red giant before finding even your first active private key (Timeframe for the sun turning into a red giant: 5 - 6 billion years [5]. Yearly chance of finding an active private key using the large bitcoin collider: approx 0.000000000000000000000000055% [6]). And that's just for finding a random private key, not a specific one.

Obviously that's based on the computational power we currently have available. However quantum computing is unlikely to have much of an impact on improving the odds of brute forcing a BTC address in practice, which is why the threat posed by quantum computing is one of mathematical prowess (ie. deriving the private key from a public key using what is essentially a computational shortcut) rather than one of brute force (ie. scanning Bitcoin's key space).

[5] https://en.wikipedia.org/wiki/Red_giant#The_Sun_as_a_red_giant
[6] https://bitcointalk.org/index.php?topic=5073899.msg48145266#msg48145266

Yep, the smaller a coin the cheaper an attack.

To be more precise, the less a blockchain spends on security in terms of fiat (ie. purchasing power) via block subsidies and mining fees the less an adversary needs to spend to achieve the majority hashrate. This is further aggrevated by the relative ease with which a GPU miner can switch between cryptocurrencies, meaning that there's an abundance of GPU hashing power floating between cryptocurrencies that can be arbitrarily retargeted at smaller coins.

Nonetheless keep in mind that even then 51% attacks make rarely economic sense except for political reasons or to manipulate the markets (ie. there's little to be directly gained from a 51% attack).

The BTC address is not the public key. It's the RIPEMD-160 hash of a SHA-256 hash of the public key, including some bits of error correction and encoded as Base58 [1]. The public key is not published until the first outgoing transaction is made from a BTC address [2], since only then the public key becomes necessary to validate the transaction.

Modern P2SH and Bech32 addresses and transactions work slightly differently, but in either case the public key is not published until an outgoing transaction is made. SHA-256 appears to be not especially vulnerable to quantum computing [3] (ie. quantum computing does not offer any advantage over classical computing for the subset of mathematical operations required for SHA-256); I think the same holds true for RIPEMD-160 but I'm not sure.

Accordingly a BTC address only becomes potentially vulnerable to quantum computing once the first outgoing transaction has been made, since in either case the public key is not known prior to that transaction.


[1] https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses
[2] https://en.bitcoin.it/wiki/Transaction
[3] https://crypto.stackexchange.com/questions/59375/are-hash-functions-strong-against-quantum-cryptography-and-or-independent-enough

To clarify for anyone else who might be reading this, BCH in this case has nothing to do with Bitcoin Cash but rather stands for Bose-Chaudhuri-Hocquenghem. I just find it a fun coincidence:
https://en.wikipedia.org/wiki/BCH_code

(it's linked in the readme, I wasn't aware of these codes myself)

That's pretty neat, I'm looking forward to see whether this will bring any practical implications for Bitcoin.



There'd be a certain irony if that approach would indeed help with on-chain scaling by means of allowing for bigger blocks with lesser downsides.



That depends. Some transactions may lead to a quadratic increase of verification times [1]. This problem is fixed with SegWit transactions, however legacy transactions are still a thing so that might be important to keep in mind.

[1] https://bitcoincore.org/en/2016/01/26/segwit-benefits/#linear-scaling-of-sighash-operations

This will depend on how effective a quantum computer will be at deriving the private key from its respective public key.

The first viable quantum attacks on Bitcoin's public / private key cryptography will probably still take days, weeks or even months to derive the private key from a public key. At this point address reusage will become a serious security risk; however one time usage of an address should still be fine for the most part.

The attack you describe (ie. in-flight, during an outgoing transaction) would become a risk once quantum computing reaches an effectiveness that allows deriving the private key within a block interval (ie. within minutes or even seconds, rather than days). At this point each Bitcoin transaction as we know it would be at risk of being diverted in an unprecedented form of double-spend attack (ie. one that requires no hashing power and allows you to double-spend someone elses coins, rather than only your own). Needless to say this would render Bitcoin useless.

However we're still very far from the first scenario, let alone the second. For all we know reaching even the first scenario could still take 10, 20 years, if we even see it come to fruition at all. Either way Bitcoin will likely have sufficient time to switch to a quantum resistant private / public key encryption and / or transaction scheme before any such attacks become close to viable.

Reporting badges sound good to me but I'm not so sure about an inflationary use of badges.

Sure it's fun, but I think it would also be detrimental to the original purpose of introducing badges as means of incentivizing desired behaviour like reporting spam -- that is, the more badges you have, the less meaningful the individual badge becomes. Now you just have a wall of badges, with the spam reporting being one of many and thus not as desirable as it should be.

That's not to say that reporting is the only forum action that is worthy of receiving a badge; I'm sure there's other use cases as well where this form of gamification could be applied. It's just that I would not go overboard with it as that would likely reduce the effectiveness of such a system. That's just my 2 sats though.

None of the above stablecoins are decentralized. Every single one of them is backed by either a centralized exchange or some other form of third party requiring trust.

I'm impressed. I'm also skeptical whether you'll be able to stay under the radar once your "rent income" increases but keep us posted. Good luck OP.

I see you've read between the lines :p

In all seriousness though, while I have no idea what the future holds in store for crypto, I doubt it that we'll see an end of it any time soon. As is I'm still convinced that for now time is still on Bitcoin's side (ie. I believe we'll have at least one or two more growth phases before we reach either widespread adoption or final capitulation).

Yes.



Yes.



Yes. No.



No.



Zero.


Crypto is dead and that's the end of it. We can all finally pack up, leave this forum and unglue our eyes from the price charts. Nothing else to see here folks, move along.

Why should Bitcoin's PoW scheme be relevant for another blockchain? Or the other way round, why should Bitcoin's PoW scheme take an unrelated blockchain into account?

I'm not sure what you are trying to do, but maybe sidechains and / or merged mining are of interest for you. Namecoin [1] comes to mind, especially given the example you provided.

[1] https://namecoin.org/

Yet Bitcoin Gold still keeps on ticking

But very true, while you don't need to hurry with getting your fork coins, there's also a chance that they won't be worth much once you get around to extracting them (case in point: the current bear market).



Something similar happened with Bitcoin Gold:

https://bitcoingold.org/critical-warning-nov-26/


OP, the above comment by cellard should be your main takeaway. Assume that any fork coin wallet is compromised and take care of security accordingly. Lest you get your coins stolen:

https://bitcointalk.org/index.php?topic=5080741.0

I'm neither a legal nor a tax expert, but I'm pretty sure that faking income from one source to cover up income from another source as to avoid taxes counts as money laundering in most legislations, including the US and the EU.

Do what you will though, I'm just some random guy on the internet Should you be audited by your local authorities (which hopefully won't happen) it's not me you'd need to convince that neither tax evasion nor money laundering is at play. If you haven't already I'd still advise on getting a tax expert aboard though, if only to avoid any slip ups.

To be fair that's purchasing habits that raise red flags with financial authorities in other countries as well, regardless of whether crypto is involved or not.



Crypto is legal in Israel [1]. Also attempting to tax illegal contraband is not unheard of [2]. I mean, heck, Al Capone's main criminal charge was tax evasion [3] and his sources of income were rather questionable.

[1] https://en.wikipedia.org/wiki/Legality_of_bitcoin_by_country_or_territory
[2] https://en.wikipedia.org/wiki/Crack_tax
[3] https://en.wikipedia.org/wiki/Al_Capone