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81  Bitcoin / Bitcoin Discussion / Re: Cryptocurrency boost: Slovenia creates first bitcoin city in the world on: June 09, 2018, 02:47:50 PM
SLOVENIA is set to open a bitcoin city in its largest shopping mall in Ljubljana, where customers can pay for goods simply using bitcoin and cryptocurrency, operating via blockchain technology, in a world first.

Good news for Bitcoin and cryptocurrency world !

I invite you to read the full article from here:
https://www.express.co.uk/news/world/971527/bitcoin-news-slovenia-bitcoin-city-Ljubljana-cryptocurrency-btc

How come those news are good for BTC and the crypto world?This is Ljubljana,not New York or London.
What happend to the idea of an crypto island,or a crypto state?Nothing,because nobody was interested.
I really doubt that people in Slovenia are hardcore crypto fanatics. Grin


But the main purpose i think is to attract peoples around the world and promote tourism in the region, national economy, and they can even expand their business and sell over internet etc ... So, in your opinion this will add no value to cryptocurrency world ?
82  Bitcoin / Bitcoin Discussion / Re: Another bad news for Bitcoin on: June 09, 2018, 04:54:09 AM
Show him this link and he will understand what is the added value:
https://coinmarketcap.com/currencies/bitcoin/

It summarizes everything !
83  Bitcoin / Bitcoin Discussion / Re: Cryptocurrency boost: Slovenia creates first bitcoin city in the world on: June 09, 2018, 04:43:53 AM
Meh, I'll beleive something like this when it actually comes to fruition and isn't just a way for a company (such as a news site) to attempt to get more clicks for themselves through advertisements. This probably isn't that good of an idea anyway, how would strores deal with TX fees and confirmations?

Lots of things to be answered on this.

I think before they invested on a big project like this, the first thing to do is to think this at first place no ?

Before launching any project, must list the advantages and disadvantages.

and well make advanced studies, business plan, ect.
84  Bitcoin / Bitcoin Discussion / Re: Cryptocurrency boost: Slovenia creates first bitcoin city in the world on: June 09, 2018, 04:31:57 AM
I believe attempts like these will not be successful if Bitcoin, in its present state, is considered. Today, Bitcoin is best used as a store of value. It is a powerful form of "sovereign asset" that cannot be taken from you and cannot be censored.

Bitcoin as a medium of exchange will come later when more efficient ways of sending them are easier to use. #LightningNetwork.

Even at this time, transactions can be made for cheap fees, since they are quite low again ... for sure LN will open many doors for the transactions, but at this current state is still possible to make cheap and fast transactions.

A great chance of success for this project!

Check this informative thread about fees:
https://bitcointalk.org/index.php?topic=2848987.0
85  Bitcoin / Bitcoin Discussion / Re: How can a goverment trace you have BTC? on: June 09, 2018, 04:24:15 AM
Prevent selling your Bitcoins locally (Inside your country), and use anonymous exchangers to sell them.

If you need Cash, you have to exchange to another online currency so you can sell it locally if you want, or using MoneyGram etc.
86  Bitcoin / Bitcoin Discussion / Cryptocurrency boost: Slovenia creates first bitcoin city in the world on: June 09, 2018, 04:14:13 AM
SLOVENIA is set to open a bitcoin city in its largest shopping mall in Ljubljana, where customers can pay for goods simply using bitcoin and cryptocurrency, operating via blockchain technology, in a world first.

Good news for Bitcoin and cryptocurrency world !

I invite you to read the full article from here:
https://www.express.co.uk/news/world/971527/bitcoin-news-slovenia-bitcoin-city-Ljubljana-cryptocurrency-btc
87  Bitcoin / Development & Technical Discussion / Re: What is RPC attack? on: June 08, 2018, 02:01:35 PM
bitcoind's JSON-RPC interface is used to issue commands to bitcoind to have it do things. Having access to the JSON-RPC interface of a node means that you have a significant amount of control over that node. For example, an attacker can dictate what nodes that node connects to, send coins from the wallet, shut down the node, etc.

The really important thing to note is the control of the wallet. If the wallet has any funds in it and the wallet passphrase is known or not set, anyone who has access to the RPC interface can send commands to the wallet that result in the coins being sent elsewhere. Thus an attacker could potentially steal your coins if the RPC interface is insecure.

To secure the RPC interface, you set a password on it. This password is most securely set by using the rpcauth configuration option. You can generate a correctly formatted rpcauth line by using the script provided here: https://github.com/bitcoin/bitcoin/tree/master/share/rpcauth. That script can also generate a secure password for you to use.

Additionally, you should add rpcallowip=<ip> lines to your config file to limit the IP addresses that are allowed to access the RPC interface of bitcoind.

Just another thing to note, actually bitcoin do not allow wildcard when using: rpcallowip=* (to authorize access from all IPs), but you are allowed to use subnet:
0.0.0.0/0 (just ipv4) or ::/0 (ipv4 and ipv6).

This lower a risk of been hacked, and add more layer of security to your node.
88  Bitcoin / Bitcoin Discussion / Re: What is your favorite source of information about cryptocurrency news ? on: June 08, 2018, 04:06:55 AM
Reddit and BitcoinTalk.

Cointelegraph was a good source, but right now i can't afford to follow them, since they are not neutral.
89  Bitcoin / Legal / Re: How is bitcoin supposed to be? on: June 08, 2018, 04:02:54 AM
Fiat money too can be oriented for criminal use.
90  Bitcoin / Bitcoin Technical Support / Re: Can't connect to node using easybitcoin.php on: June 08, 2018, 03:43:01 AM

You can use JSON RPC CLIENT:

Code:
<?php
/*
COPYRIGHT

Copyright 2007 Sergio Vaccaro <sergio@inservibile.org>

This file is part of JSON-RPC PHP.

JSON-RPC PHP is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

JSON-RPC PHP is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with JSON-RPC PHP; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

/**
 * The object of this class are generic jsonRPC 1.0 clients
 * http://json-rpc.org/wiki/specification
 *
 * @author sergio <jsonrpcphp@inservibile.org>
 */
class jsonRPCClient {

/**
 * Debug state
 *
 * @var boolean
 */
private $debug;

/**
 * The server URL
 *
 * @var string
 */
private $url;
/**
 * The request id
 *
 * @var integer
 */
private $id;
/**
 * If true, notifications are performed instead of requests
 *
 * @var boolean
 */
private $notification false;

/**
 * Takes the connection parameters
 *
 * @param string $url
 * @param boolean $debug
 */
public function __construct($url,$debug false) {
// server URL
$this->url $url;
// proxy
empty($proxy) ? $this->proxy '' $this->proxy $proxy;
// debug state
empty($debug) ? $this->debug false $this->debug true;
// message id
$this->id 1;
}

/**
 * Sets the notification state of the object. In this state, notifications are performed, instead of requests.
 *
 * @param boolean $notification
 */
public function setRPCNotification($notification) {
empty($notification) ?
$this->notification false
:
$this->notification true;
}

/**
 * Performs a jsonRCP request and gets the results as an array
 *
 * @param string $method
 * @param array $params
 * @return array
 */
public function __call($method,$params) {

// check
if (!is_scalar($method)) {
throw new Exception('Method name has no scalar value');
}

// check
if (is_array($params)) {
// no keys
$params array_values($params);
} else {
throw new Exception('Params must be given as array');
}

// sets notification or request task
if ($this->notification) {
$currentId NULL;
} else {
$currentId $this->id;
}

// prepares the request
$request = array(
'method' => $method,
'params' => $params,
'id' => $currentId
);
$request json_encode($request);
$this->debug && $this->debug.='***** Request *****'."\n".$request."\n".'***** End Of request *****'."\n\n";

// performs the HTTP POST
$opts = array ('http' => array (
'method'  => 'POST',
'header'  => 'Content-type: application/json',
'content' => $request
));
$context  stream_context_create($opts);
if ($fp fopen($this->url'r'false$context)) {
$response '';
while($row fgets($fp)) {
$response.= trim($row)."\n";
}
$this->debug && $this->debug.='***** Server response *****'."\n".$response.'***** End of server response *****'."\n";
$response json_decode($response,true);
} else {
throw new Exception('Unable to connect to '.$this->url);
}

// debug output
if ($this->debug) {
echo nl2br($debug);
}

// final checks and return
if (!$this->notification) {
// check
if ($response['id'] != $currentId) {
throw new Exception('Incorrect response id (request id: '.$currentId.', response id: '.$response['id'].')');
}
if (!is_null($response['error'])) {
throw new Exception('Request error: '.$response['error']);
}

return $response['result'];

} else {
return true;
}
}
}
?>

Example of use:

Code:
<?php
function generate_address() {
require_once 'jsonRPCClient.php';
$bitcoin = new jsonRPCClient('http://'.json_username.':'.json_password.'@'.json_server.':'.json_port.'/');
$address $bitcoin->getnewaddress();
return $address;

}
echo 
generate_address();
?>
91  Bitcoin / Bitcoin Technical Support / Re: transaction time on: June 08, 2018, 03:33:12 AM
You can accelerate your transaction using:
https://pool.viabtc.com/tools/txaccelerator/

This helped many times in the past, but your transaction must have minimum of 0.0001 BTC of fees in order to be accepted.

You have just to put your Transaction ID and fill the Captcha, and you it's done.

You must choose the right time to submit your TXID since i think only 100 transactions accepted each hours.
92  Alternate cryptocurrencies / Altcoin Discussion / Re: What makes a altcoin valuable on: June 08, 2018, 03:16:50 AM
The most valuable thing i will see in each new altcoin, is what problem do it solve ? what is the vision of this altcoin, like this we can judge if it worth investing on it or not.

The second important factor is marketing, for any new product even if you have the best idea in the world, if someone don't know about it ... your project falls in the water !
93  Alternate cryptocurrencies / Altcoin Discussion / Re: Patience is the key on: June 08, 2018, 03:09:46 AM
Nice advice, this is the key of success in all areas.
94  Bitcoin / Development & Technical Discussion / Re: Transfer a btc full node to another server on: June 07, 2018, 10:47:34 PM
The best solution for you, is to install btcd in the new OS.

In the other hand, install apache server or nginx in your node server, zip data folder of your bitcoin node, move zipped file to /var/www/html/ or the default path where you are able to access it from the web: http://YOUR_IP/zipped_file.zip.

Once done, go to your new server, and download it using wget command or any similar one like CURL etc...

Quote

And extract it and point btcd to your new data folder.
95  Alternate cryptocurrencies / Altcoin Discussion / Re: I want to learn to build a PoW/PoS coin with Masternodes on: June 07, 2018, 10:41:37 PM
If you want to build your own coin, first thing to do is to learn C++ programming language.

When it's done, you have to learn how Blockchain works and all things related to it.

Good ressources from here:
https://bitcoin.org/en/developer-guide

https://hackernoon.com/learn-blockchains-by-building-one-117428612f46
https://jeiwan.cc/posts/building-blockchain-in-go-part-1/

From there, you can check another altcoins code from github to be inspired from them and learn their technology.
96  Alternate cryptocurrencies / Altcoin Discussion / Re: As hackers and scammers attack the projects on: June 07, 2018, 08:23:35 PM
Security of your clients are important at this level.

You must take all necessary measure to avoid any lost and put your efforts in the security of your project.
97  Bitcoin / Development & Technical Discussion / Re: Need an explanation over 51% attack. on: June 07, 2018, 06:21:52 PM
In order to calculate how much money do you need to perform a 51 attack on bitcoin:

Current hashrate (Total network hashrate): 34630131,855 TH/S (From https://blockchain.info/stats)

We choose our miners from here:
https://en.bitcoin.it/wiki/Mining_hardware_comparison

Let's take for example: Antminer S9
Hashrate = 14 TH/S
Consumption = 1.375 kW

Cost of harwares:
Hardware = Current hashrate * Price of Antminer S9 / Hash produced by Antminer (per seconds)
Hardware = 34630131,855 * 2400$ / 14
Hardware ~=  5,936,594,032 $

Number of antminers = Hardware / 2400 ~= 2,473,580

Cost of electricity:
Electricity consumption per day = Number of antminers * consumption * 24
Electricity consumption per day = 2,473,580 * 1.375 * 24
Electricity consumption per day ~= 81,628,140 kWh

Electricity cost per day = Electricity consumption per day * Cost per 1kWh
Electricity cost per day = 81,628,140 * 0.045$ (Electricity pricing - Depend on countries)

So attacker have to pay 3,673,266 $ of electricity per day !

This without make calculation of transport, renting or buying local where to install all this stuff, without counting the difficulty to get this number of miners and electricity power required to get them working all.

And countring the risk that the attack will not be a success and many other factors ...
98  Bitcoin / Development & Technical Discussion / Re: What is RPC attack? on: June 07, 2018, 04:36:05 PM
Not sure if that someone was referring to a special kind of RPC attack, but in general it is wise to set up a strong rpcpassword (think 40 characters and beyond) as mentioned by btj.

Also make sure that rpcallowip is either set to localhost only or not set at all (making it default to localhost). If you need to access the RPC interface from a different server, but within the same local network (ie. 192.168.x.x) set it to the respective IP. Accessing the RPC interface from a different server over the internet is a very bad idea and should be avoided at all cost.

Finally keep in mind that all of this is worth nothing if the server itself is not secured enough.


[...]

But in the latest versions of bitcoin withdraw funds is removed using JSON RPC remotely, but an attacker can check for your coin balances etc.

[...]

Got any source on that? This doesn't seem to be mentioned in the recent release notes:
https://github.com/bitcoin/bitcoin/blob/master/doc/release-notes/release-notes-0.16.0.md
https://github.com/bitcoin/bitcoin/blob/master/doc/release-notes/release-notes-0.15.1.md

I was unable to perform that action in a recent work for my client, i was required to make a script that serve as API to perform that for the server itself.

But this can be related to some other issues in the custom altcoin he is using, or something else.

Locally the command work well, but when launched remotely the transaction is not sent (Note that the remote IP address was added and whitelisted in bitcoin config file.)
99  Bitcoin / Development & Technical Discussion / Re: What is RPC attack? on: June 07, 2018, 02:43:36 PM
Purhapse he mean Brute Force Attack from JSON RPC.

You have to use strong password and username in bitcoin.conf.

But in the latest versions of bitcoin withdraw funds is removed using JSON RPC remotely, but an attacker can check for your coin balances etc.

I didn't tried if dumpprivkey method can be passed.
Then how withdraw done by what? if not using json rpc.

Withdraw done using JSON RPC but locally and not remotely.

Must have access to your server node and make withdraw from there.
100  Bitcoin / Development & Technical Discussion / Re: Estimating transaction size in bytes per element of the transaction on: June 07, 2018, 04:47:05 AM
Quote
Size of transaction = Number inputs * (Input Size) + Number of outputs * (Output Size) + 10 Bytes extra fixed fee required for the framework of the transaction

How to get the P2PKH input size ?

Quote
PREVOUT  + SCRIPTSIG + sequence = 32 + 4 + 1 + 1 + (71 or 72) + 1 + 33 (Compressed) + 4 = 147 or 148

Quote
PREVOUT: hash (32 bytes)
         index (4 bytes)
SCRIPTSIG: length (1 byte)
           CONTENTS: push opcode (1 byte)
                     signature (71 or 72 bytes)
                     push opcode (1 byte)
                     pubkey (33 bytes for compressed, 65 for uncompressed)
sequence (4 bytes)
Source: https://bitcoin.stackexchange.com/questions/48279/how-big-is-the-input-of-a-p2pkh-transaction

Quote
   Legacy input size: 148 bytes (compressed)

    Legacy output size: 34 bytes (compressed)

    Segwit input size: 104 bytes
    Segwit output size: 32 bytes

Outputs for P2PKH and P2SH are both the same size: 34 bytes

So let's take an example and calculate the size:
https://blockchain.info/tx/7e46a5ea9d9c19cd4d0c3d0a287419d7c1ae13049ac7ab8860b6ee0cec4ead17

We have 1 input
There 2 Output

Quote
So the transaction size ~= 13 * 148 + 2 * 34 + 10 ~= 226 Bytes

Check this link, you will learn more about it:
https://blog.rmcsoft.com/how-to-calculate-bitcoin-transaction-fee/
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