You can't expect a more detailed description than "install core, use it with your web applicatoin", if you don't give out more information regarding your application/service.

If you plan on creating a block explorer, you need to have all transactions indexed. This option has to be set before syncing core.
If you plan on opening a webshop / something similair, you don't need all transactions indexed.

In both cases, you'll need to use the JSON-RPC interface to get the necessary information from your node.
Your application will send commands to your node (e.g. what is the balance of address X). Then you can work with the answer.
And you can set a script to be run each time a new block/transaction to your wallet is received (e.g. whenever you receive a transaction -> add something to the DB).

Yes, you can.
But not all wallets have the option to adjust the fee.

Some only let you chose the fee via a slider, and some don't offer that option at all.




There are. But at the same time they are less secure.
Bitcoin is - by far - the most secure cryptocurrency.

On the one hand, because of this:


Roughly 2/3 of network connected printer can be hijacked through the internet. Even if the policy only allows printing within the local network.
This can lead to sending print jobs to the printer which execute Postscript or PJL commands. And this allows an attacker to extract previous printer jobs (if being captured). Accessing a malicious website is enough for that.

And on the other hand, the source code of the website could be manipulated. E.g. using a manipulated RNG, which won't create truly random private keys.
It is not hard to shrink the space to an amount too high for random collisions of different people generating the same private key, but at the same time low enough to be able to bruteforce them.

Additionally, i wouldn't trust any javascript library with sensitive crypto operations.

5$ for a relatively standard transaction with 2 inputs and 2 outputs (legacy) is more than 140 sat/B. And if you used segwit, 180 sat/B. You heavily overpaid.
Currently 1-2 sat/B are enough to get your transaction confirmed within a few blocks. That's roughly 0.02 USD for segwit and 0.03-0.04 USD for legacy.

Which wallet did you use?
Either your wallet estimated the fee poorly (which almost always is the case) or you chose a way too high fee by your own.

Even when the fees spike (like 1 - 2 weeks ago), a fee of 20-30 sat/B was enough to get your transaction confirmed in a reasonable timeframe.

And a mistake already in the first few lines..


This "simulator" can't be educational at all when including such embarrassing mistakes.
Seems like this whole website is worthless and shouldn't be used at all. I wouldn't recommend it, even without looking at the rest of it.

I guess you meant addresses ?
Note that a public key is not the same as an address. The public key is being hashed to retrieve the address (sha256 and ripemd160 + checksum).

@OP:
Regardless of the initial statement:
Do not use any website to create a paper wallet. Not even after downloading and running it offline.
The usability is not worth the risk.

By gaining access to the medium where the private key is stored.

And this - by the way - has nothing to do whether you have used the private key to sign something or not (assuming you are talking about ECDSA).
If you are in fear that your private key might get compromised by simply signing a transaction/message, be assured.. that is not the case.




Well.. its cryptography.
It kind of needs to be complex to be robust against several types of attacks.

Yes, the hash is the transaction id.
In your case: 9f91659f58998d442d36a1c8e37e88319a3ca410af87a4f554e28b56fde34e16.

The transaction is already confirmed, so i guess your problem is solved now anyway?


For the future, please do not shorten any URLs when posting here.

Ich kann dir zwar nicht beim Platinenlayout helfen, aber wenn benötigt kann ich die Bestellung in China für dich abwickeln.
Habe schon ein paar mal PCB's in China anfertigen lassen.

Momentan ist das mit dem Versand aber so eine Sache.. Langsam öffnen die Flughäfen wieder aber es ist noch einiges an Backlog in den Postämtern dort vorhanden.
Ende Juli könnte allgemein knapp werden. Bei einer Lieferung aus China (angenommen du möchtest keine 30-50€ für Expresslieferung zahlen), musst du derzeit mit ca. 4-8 Wochen Lieferzeit rechnen.

Du musst einen Port nur bei eingehenden Verbindungen freischalten.
Nach außen kann man immer kommunizieren.

Wenn du beispielsweise deine Browser öffnest und eine Website aufrufst, dann macht das Betriebssysteme einen Port für dich auf (unprivilegierter port > 1023) über den du dann den Webserver (port 80) ansprichst.
Wenn du nun selber einen Webserver betreiben möchtest, musst bei dir einerseits auf Port 80 eine Anwendung (webserver) lauschen und andererseits muss der in der Firewall (Router Settings) freigegeben werden.


Das heißt:
Wenn du dich nur nach außen verbinden möchtest, Transaktionen empfangen und versenden willst, Blöcke anfragen -> dann musst du keinen Port öffnen.
Wenn du das Netzwerk unterstützen möchtest, indem du zulässt dass andere Clients sich mit deinem Node verbinden -> dann musst du den Port im Router freigeben.

It depends on the definition on double spending.

Theoretically, it is. Because you are using the same input twice.

However, a double spending attack implies that the same input is sent to another address to deceive the recipient of the first transaction.
There are multiple ways to achieve that (e.g. race attack, sybil attack, ... ). Some of them require multiple nodes spread, others require to give up on a block reward, etc.. )

In reality, double spending attacks are not feasible since merchants wait for at least one confirmation. 0-conf transactions are not to be trusted.

Can you confirm that the address indeed is part of your nano s ?
Using electrum would help here quite a bit. Just set electrum up as interface for your nano s (do not enter your mnemonic code).
Then we can easily check whether the address you used to withdraw is from your ledger with a simple command.

Unfortunately ledger live is pretty limited in its functionality.

But if you can confirm that the address you saw on the ledger screen is the same you used on kraken, you didn't lose your BTC.
It is probably just a connection/display issue with ledger live and/or their server.

If the private keys are not stored on a completely air-gapped system with no interfaces (wifi, bluetooth, etc..), it can not be considered an offline wallet (and neither a cold wallet).
So there is still no difference between those two terms.



See above.
If a wallet either:
1) has been generated on an online device
2) is at some point online
3) is not completely isolated

it can not be considered an offline- or cold wallet.
There is no offline wallet which does not meet the criteria.

A cold wallet is an offline wallet. This includes cold-wallet setups and paper wallets.




Sure, there are people who think that when your computers goes offline for an hour, it can be considered an offline wallet.
But this obviously is wrong.

Still doesn't change the fact that a tag and warning flag indeed is appropriate.
If we were talking about a type #3 flag against this user, i'd agree with you. But a warning flag is definitely necessary.
We don't want additional user to see this thread and potentially even lose money by using this scam mixer.

Yes. A standard hot wallet.



Yes. A standard cold-/offline wallet.



What you are describing here is a watch-only wallet.
This has nothing to do with "offline mode". This wallet is run on an online computer. That's far away from being offline.

This is a watch-only wallet: A wallet which contains the master public key to derive public keys / addresses and to create unsigned transactions.

Why anyone would call that an "offline mode" is beyond my imagination.

But now i understand where your confusion comes from.
What armory means with "watch-only/offline" is to create a transaction on the watch-only wallet and use the offline wallet to sign it. That's why there is "offline" in the security-tab for this setup.
The phrasing is pretty bad.


I hope this cleared out any misconceptions you had regarding wallet types. If you still have any further questions, feel free to ask.

So ?
How is that related to the fact that each cold wallet is an offline wallet and each offline wallet is a cold wallet ?




"hot wallet running in offline mode on online computer" 
This doesn't even make sense.

You can not run a hot wallet in "offline mode" on an online computer.

There are 2 options:
1) It is a hot wallet. Then an "offline mode" itself does not exist. Even if your PC is offline for a specific timeframe, it still has nothing to do with an offline wallet or so-called "offline mode". It it is stored on an network-connected device, it is a hot wallet.
2) It is an offline wallet which means it is stored on a device which will never be connected to a network. In this case it has nothing to do with a hot wallet.




Yes. And another term would be: offline wallet.
If your private keys are not on an always-offline and air-gapped device, this is not an offline wallet and not a cold wallet.


I agree with you that armory did phrase that quite ambiguous.
However, by pure logic..
Either your private keys are stored on a device which is connected to the internet / a network (even if only for a short amount of time): Not am offline wallet, not a cold wallet.
Or, your private keys are stored on an offline device / not connected to any network: Offline / cold wallet.

There is nothing in between.

Die meisten Wallets lassen es zu, Watch-only adressen zu hinterlegen.
Wenn du also sowieso schon ein Wallet benutzt, dann schau doch ob es dort funktioniert. Dann hat man wenigstens alles an einem Ort.

Bei Mycelium funktioniert das jedenfalls problemlos.

Sonst gibt es auch diverse "Address"- oder "Balance Checker" im Playstore.

Electrum itself is just an interface which manages your private-/public key pairs.
It loads a wallet file which stores the relevant information.

If you uninstall electrum, you did not delete the wallet file. So upon reinstalling it, you can open the same wallet file and have the same private keys and therefore also the same addresses.
If you delete the wallet file after uninstalling electrum, you will have the ability to create a new wallet or restore an old one when reinstalling it.
With your backed up mnemonic code (12/24 words), you are able to recreate the same wallet (same private keys -> same addresses).

Always make sure to have a backup of your mnemonic code. Do not only rely on an electronic device to store your private keys.

AFAIK there is no wallet which supports the electrum mnemonic code (except for electrum obviously).



Since most wallets (basically all except for electrum) use BIP39, this is also supported by electrum when importing a wallet.
When creating a wallet in electrum it however uses its own way to create a mnemonic / derive the keys. So electrum mnemonics are only usable within electrum.

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