Latest posts of: Coding Enthusiast

Just FYI in the link Danny gave this: 0C28FCA386C7A227600B2FE50B7CAE11EC86D3BF1FBE471BE89827E19D72AA1D is your number (integer) but in another format (hex) and if you convert it to a number it is this number: 5500171714335001507730457227127633683517613019341760098818554179534751705629 (I used BigInteger Structure in .Net framework)

Quote from: achow101 on December 15, 2016, 04:05:35 PM

♯♯ the transaction could be accepted earlier or later than the time specified by the locktime.

What if locktime was Block number (< 500000000) instead of UNIX timestamp (>= 500000000) I suppose it can no longer be mined before the specified block, right?

As an update I want to say the Wireshark helped a lot. My mistake in my message was the length fields which I forgot to cut in half (hex length/2) and also it was interesting to find out that the receiving node returns a reply even to messages with error like mine with a reject message saying error parsing message
https://bitcoin.org/en/developer-reference#reject

Now I've got to figure out how to stack these send and received on top of each other using threading.

Something weird: the node that I sent the wrong message to replied with the following messages respectively!

reject
ping
getheaders
addr
inv

the weird part is that it skips version and verack!

Quote from: https://bitcoin.org/en/developer-reference#version

Until both peers have exchanged version messages, no other messages will be accepted.

I guess that only goes for "accepting" not "sending"?!

@valley365
Sorry I thought my question was clear that I am creating the message on my own based on the documentation not with any software or library out there. And that example in OP is the message I have generated with my own code.

I will update this topic, right now I apparently have some troubles with my understanding of TCP Grin

and how to use a freaking Socket!

Since I am learning I wanted to know if there there is a way to check if the Message I have generated is valid before sending it out?

I am talking about Messages that you send to a node in order to establish communication, starting with version.

Example based on Docs

Quote

My header:f9beb4d9 76657273696f6e0000000000 cc0000006a000000 3fd3a680

My message:7e110100 0000000000000000 fa084d5800000000 0000000000000000 00000000000000000000ffff52a1377f 208d 0000000000000000 00000000000000000000ffff7f000001 208d fa084d5800000000 2814 2f437573746f6d436c69656e743a302e392e302f 00000000 00

A couple of questions regarding this:
1) Why should I even provide "addr_recv services" field? And does it matter if I provide 0 or 1?
2) Will receiving node reject "addr_recv IP address" field if it is 127.0.0.1 instead of its own IP or a false IP?
3) "addr_trans services" Why am I telling this again if it is identical to "services" above?
4) I don't get usage of "nonce" when I have already provided "timestamp" which will change every time it is generated and it will be bigger. And can I use the same thing again here?
5) What is the criteria to get banned by a node? For instance will I be banned if I send a wrong message on first attempt? Also will I receive any reply if my message contains errors or will it be ignored?

Quote from: BooToo on November 30, 2016, 08:07:53 PM

For example (only 6 words) 1613 sister 0003 able 0832 gun 0558 eat 0242 bullet 0082 any

Jane 01 16 13 00 03 Peter 01 08 32 05 58 Steve 01 02 42 00 82 (in alphabetical order )

This is a very interesting method. Thanks for sharing.

Quote from: NeuroticFish on December 10, 2016, 03:07:00 PM

What if that txt file changes? What if eat will be 0559?
What if the file is deleted?

This being said, you better keep a copy of that file on your phone. And then your method becomes pretty good.

As far as I can tell, the wordList has never changed. https://github.com/spesmilo/electrum/commits/master/lib/wordlist/english.txt
It has moved around but never changed.

Even if Electrum repository disappears there are 485 forks and lots more clones you can easily find on the internet to recover the english.txt file.

Quote from: QuestionAuthority on December 09, 2016, 01:37:17 PM

♯ Bitcoin has enough nodes ♯

I do not agree with this part. We always need more nodes. Bitcoin nodes are like the back-bone of bitcoin network and we always need Full Nodes that are always on, have at least 8 connections and have a high-bandwidth connection to the Internet.

Quote from: adaseb on December 09, 2016, 12:42:11 PM

I would like to use Electrum instead of Bitaddress Paperwallets because I get a little paranoid not knowing if I will be able to ever withdraw any BTC from the private keys since I cannot test them prior before actual sweeping.

https://bitcointalk.org/index.php?topic=339810.msg3647576#msg3647576
You can test it literary with any bitcoin wallet out there. Just remember to be on a live linux that doesn't save anything and check the signature of the downloaded file.

Just an addition to ranochigo comment

Code:

sudo apt-get install python-qt4 python-pip
sudo pip install https://download.electrum.org/2.7.12/Electrum-2.7.12.tar.gz

7) You can also change this behavior by deselecting Use Change Address from Tools > Preference

8 ) You are broadcasting "bitcoin transactions" so technically you can even use a web service to push the signed transaction. Just open the .txn file that Electrum gives you with a text editing software like Notepad and you can see a JSON which looks like this:

Code:

{
    "hex": "010000000......", 
    "complete": false
}

Copy the hexadecimal in front of "hex": and paste it in a push service like https://blockchain.info/pushtx

Problems with this tutorial:
1) It is not free, if you want to pay $200 for a laptop on Amazon why not just buy a Trezor!
2) It uses Window!
3) With Electrum you don't need to save the wallet.dat on multiple Flash drives. You can just save the seed (best if encrypted seed).
4) Step Six sounds stupid to me. As long as there are live linuxes without persistence there is absolutely no need for using: Windows 7, Truecrypt, File Eraser.

Additional goof: the article keeps saying "your bitcoins are hanging in the blockchsin", "Bitcoins never touch your wallet". These are not correct statements.

This is a "VirtualBox" problem so you may want to try their dedicated forum to ask about it. https://forums.virtualbox.org/

But my guess is that your problem is because of the new operating system+new hardware in the second computer you have transferred the virtual machine to.

In your second computer inside virtualbox go to Settings and then go to Network tab and see if you can fix it by changing those settings.

Also in your first computer that you first made that virtual machine, try "Cloning" the machine instead of simple copy paste or .VDI file.
Right click on the name of that VM inside virtualbox interface and select "Clone..." I have never tested this but try selecting the option about "Reinitialize the MAC address...."

Because the SHA256 class ComputeHash() function only takes a byte array. And the code you quoted is the way to convert hex to byte array. (every two characters represent one byte)
eg.
int : hex
1 : 01
2 : 02
10 : 0A
...

This page has a Python example if that is the language you are comfortable with: https://en.bitcoin.it/wiki/Block_hashing_algorithm

Quote from: Lauda on December 06, 2016, 05:33:36 PM

♯For example, Electrum has a list of 'official' servers available in the client IIRC. ♯

I don't know if we can call these servers official but there are a list of servers hard-coded in the client. I may be wrong but this is possibly for finding an initial number of servers (similar to core and finding peers the first time)

Quote from: Coin-Keeper on December 06, 2016, 07:52:27 PM

Lauda is correct about that stuff. In addition you can handle some of the trust issues on your own by selecting the onion Electrum servers from the list. This allows you to stay anonymous even from the actual Electrum server you are using. Nobody in the entire route can sniff your traffic that way because there is no exit node.

The problem with using Electrum server (or generally a third party SPV server for any other wallet) is not revealing your IP. The problem are two things:
1) Privacy: For example with Electrum the servers see all your addresses and transactions and in case they keep log your privacy is compromised. In this case your IP is the least important.
Solution: use a full node yourself, use servers that promise no-log (not fool proof), use different wallets

2) Trust: When you are relying on a server to tell you about your balance, transaction, confirmation,... you must trust that said server is telling you the truth.
Solution: wait for more confirmation, change server, double check on an online block explorer

Some additional good information

Quote from: franky1 on December 06, 2016, 03:53:21 PM

♯

I agree that with proper documentation things are much easier to understand. But the argument OP is making is not about documentation.

Also about sloppy coding, if you see this and know a much better way and also capable of coding, I am curious to know if you have ever done anything about it like opening an issue on GitHub or changing the code to that better way and submitting it through pull request?

Quote from: BADecker on December 06, 2016, 03:18:15 PM

♯
To the general public, open source means nothing. All it does is make them feel comfortable, so that if there is a malicious programmer, he can attack them easier by saying that his program is open source.

Now you are going off-topic. You are comparing bitcoin (see the image I added) with a random malicious programmer's source code. Again you are using a correct fact to make a wrong conclusion.

Yes it is possible that a malicious programmer makes a code and fools people by only saying it is open source. I have already found 3 and reported them to GitHub and they were removed.

But what you say about malicious code is not possible about bitcoin that many are using and checking each commit's changes.

If any developer could post the results of this page: https://github.com/bitcoin/bitcoin/graphs/traffic I think it could answer many of your questions.

Quote from: DannyHamilton on December 06, 2016, 01:53:53 PM

Any programmer that wants to understand it, has the opportunity to do so. It isn't very complicated at all.

I (as a novice programmer) just want to confirm that this IS possible, not easy because of many custom variables and other complications but going through the documentation and code it is possible.

You have a bad approach in talking about what you have in mind. You have some good points here and there but at the same time you are wrong about lots of other things for example Ubuntu Kernel is also Open source or the same with Firefox and all the things you say are true about millions of people who are using these.

Open source means anyone can go to the source code: https://github.com/bitcoin/bitcoin looks at it and report publicly if he/she finds any shenanigans and also anyone can use the code to build their own code:
https://github.com/spesmilo/electrum
https://github.com/keepkey/multibit
https://github.com/etotheipi/BitcoinArmory
https://github.com/blockchain (blockchain.info)
....

What end users can do is either learn a programming language and read the code themselves or trust hundreds of others who are doing it.

You take the header of the block, then perform two Sha256 on it= Sha256(Sha256(Block_header) and then report the result in Little-Endian order.

Details:
https://blockexplorer.com/api/rawblock/000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f

Block_header= Version(4)+hashPrevBlock(32)+hashMerkleRoot(32)+Time(4)+Bits(4)+Nonce(4)

Code:

0100000000000000000000000000000000000000000000000000000000000000000000003ba3edfd7a7b12b27ac72c3e67768f617fc81bc3888a51323a9fb8aa4b1e5e4a29ab5f49ffff001d1dac2b7c

In C#

Code:

string s = "0100000000000000000000000000000000000000000000000000000000000000000000003ba3edfd7a7b12b27ac72c3e67768f617fc81bc3888a51323a9fb8aa4b1e5e4a29ab5f49ffff001d1dac2b7c";
           
            int NumberChars = s.Length;
            byte[] bytes = new byte[NumberChars / 2];
            for (int i = 0; i < NumberChars; i += 2)
                bytes[i / 2] = Convert.ToByte(s.Substring(i, 2), 16);

            System.Security.Cryptography.SHA256 sha = new System.Security.Cryptography.SHA256Managed();

            byte[] b2 = sha.ComputeHash(bytes);
            byte[] b3 = sha.ComputeHash(b2);

            if (BitConverter.IsLittleEndian)
            {
                b3 = b3.Reverse().ToArray();
            }

            StringBuilder result = new StringBuilder();
            for (int i = 0; i < b3.Length; i++)
            {
                result.Append(b3[i].ToString("x2"));
            }
            string r = result.ToString();

Code:

000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f

Fixed a bug with Price services and released version 2.0.0 by merging the MVVM branch.

Quote from: tcats on December 02, 2016, 11:24:46 PM

i accidentally sent .2575 bitcoin to a helix light scam and it has no confirmations yet.
Can someone one here please help me to do a Replace-By-Fee or anything else to not lose my bitcoin?
Thanks.

Just FYI, a Replace-By-Fee transaction means you change the fee in the same transaction to the same receiver to be confirmed faster.
You say "scam" so I guess you are looking for a different kind of thing.

Quote from: 0xfff on December 02, 2016, 03:03:44 PM

Why don't you make it an SPV client instead of trusting third party companies like blockchain.info?? It would be more secure.

I was actually thinking about this the other day but I have no idea where to start.