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1  Bitcoin / Development & Technical Discussion / 51% Attack on: January 23, 2020, 08:36:32 PM
Following scenario: A government would like to destroy Bitcoin. It buys a significant number of ASICs to build up a huge mining farm and carries out a 51% attack.
From my point of view it will not be so easy to buy so many ASICs as once - what do you think?
Another question: Will it be noticed (how?) that somebody buys a big stack of ASICs and/or are we able to identify such a behavior monitoring the network's hashrate?
2  Bitcoin / Development & Technical Discussion / How does a miner receives a transaction fee on: January 23, 2020, 08:23:05 PM
Each block has a coingen transaction for the block subsidy - so far so good.
But how does the miner gets the fees of transactions in a block? Is there a "getTransactionFees()" transaction?
3  Local / Trading und Spekulation / Android App für Kurse/Indikatoren on: February 05, 2018, 10:03:14 PM
Kennt jemand von Euch eine Android App die neben dem aktuellen Kurs auch Indikatoren (RSI, MACD u.ä.) anzeigt? Vorzugsweise in einer Tabelle und nicht in einem Diagramm (wird auf einem kleinen Handy-Display dann eh zu unübersichtlich).
4  Local / Trading und Spekulation / Telegram Bots für Kurse/Indikatoren on: January 06, 2018, 02:32:35 PM
Gibt es Bots die einem den aktuellen Bitcoin-Kurs per Telegram schicken können?
Interessant wären auch weitere Indikatoren wie RSI, MACD u.ä. sowie Informationen zu Altcoins.
5  Local / Trading und Spekulation / Gunbot on: December 28, 2017, 06:07:11 PM
Gibt es hier Gunbot User?
Würde mich gerne über Strategien, Einstellungen und Coins die man mit Gunbot handelt austauschen.
6  Local / Presse / [2017-11-07] "Verteilter Speicher: Dokumente an der Blockchain" on: November 08, 2017, 04:30:54 PM
Artikel der u.a. Sia und StorJ erwähnt.
7  Alternate cryptocurrencies / Altcoin Discussion / Blackcoin Wallet Passphrase mistyped - Bruteforce on: October 26, 2017, 11:33:32 AM
Summary: I executed a (limited!) brute force attack on a wallet where I mistyped the passphrase. Attached is a short tutorial how to make it.

Long story: In March 2017 I created a wallet. I keyed in my passphrase with 70 characters long (yes it is long), wrote it down, bought Blackcoin. Next day I tried to open it, but it seems to be that I mistyped (two times) the passphrase. So I started to make a long research how to "hack" it. I finally figured that I can make a limited brute force attack by using RPC. So, I got familiar with curl (RPC tool) and created a batch-script with Excel where I just changed one character per try. I ended with 5200 tries.

And boom: It worked! It was try number 2814 which worked. So, I really just mistyped one single character.
The wallet has been opened once again. So now I have access to my Blackcoins.


I was using the old blackcoin-qt (on windows) because the wallet was created with this one. I do not know if it is compatible with lore.
Situation is that you remember (more or less) the passphrase, but you think that you just mistyped one character.
Idea is to make a limited brute force attack on the wallet - so, to test different passphrase which are similar to your remembered one.

we will create a script (batch) which calls the blackcoin-qt (as server) via RPC and try to open the wallet with different passphrases.

What did not work

I found some hints concerning hashcat and bitcoin2john (also for Blackcoin), which enable you to retrieve the seed out of the wallet and to make a bruteforce on the hash of the seed (with hashcat).
But it did not work, because the blackcoin wallet seems to be different than the bitcoin wallet.

There is also no direct commandline parameter for opening the wallet with passphrase. So I started to work with RPC.

Using the blackcoin-qt as a server

Switch into C:\Users\myusername\AppData\Roaming\BlackCoin and place a blackcoin.conf file here. This should contain (at least) these entries:
# server=1 tells BlackCoin to accept JSON-RPC commands.

# You must set rpcuser and rpcpassword to secure the JSON-RPC api

# Listen for RPC connections on this TCP port:

# You can use BlackCoin or blackcoind to send commands to Bitcoin/bitcoindBlackCoin/blackcoind
# running on another host using this option:

Start blackcoin from the commandline with the server parameter like this:
blackcoin-qt -server=1

Test RPC Calls with curl

Download curl (an RPC tool for the commandline):

For this test you should use a new generated wallet with a password you know.

First test with the getinfo method, which shows you if the connection to the Blackcoin Daemon is established:
curl --header "Content-Type: application/json" --data-binary "{\"jsonrpc\":\"1.0\",\"id\":\"curltest\",\"method\":\"getinfo\",\"params\":[]}" http://user:password@

If you do not get any connection, you can also use netstat -a to see if your machine is listening on the port 15715.

Finally, the method to open the wallet via RPC (uses two parameters)
curl --header "Content-Type: application/json" --data-binary "{\"jsonrpc\":\"1.0\",\"id\":\"curltest\",\"method\":\"walletpassphrase\",\"params\":[\"mySecretWalletPassword\",50]}" http://user:password@

Note the output you get, when you use the correct password:
Later we want to search in a logfile for the expression "error":null in order to identify the correct password

Generating the Bruteforce Script
I used an Excel file to create a script. On the basis of the so-far-remembered-passphrase and a selection of possible characters this scripts changes for each row only one character.
I ended up with roughly 5000 rows, but I used a very long passphrase (70 characters).
Using the Excel output you can create a script out of it.

If you are interested in the Excel file please send me an PM.

Start the script (batch) and pipe the output into a log:
myScript.bat > log.txt

When the batch finished search for the expression "error":null
If you found it, you found the password in the line above the expression.

I used the old blackcoin-qt (not Lore), because the wallet has been generated with blackcoin-qt. Lore should use the same RPC implementation, but it is untested if this tutorial also works with Lore.
I used this on Windows I do not know if this will also work on Linux.
Some special characters are a little bit tricky in curl, because some of them like "<" let curl crashes. Perhaps you can escape these special characters somehow.
8  Bitcoin / Bitcoin Discussion / Analogy for explaining Bitcoins on: October 04, 2017, 10:32:15 AM
I am looking for analogies explaining the concepts of Bitcoins especially for non-technical people.
Beside the standard concept (Bitcoin, Mining, Ledger, Doublespend-Attacks) also an Analogy on Soft-/Hardforks would be interesting.

So far, I found this one:
It is quite good but I would be happy to have another one.

Another analogy (in German) is this one:
In sum: It explains soft-/hardforks using the analogy to a vegeterian restaurant which plans to add meat-dishes to the menu (hardfork) or to replace butter by vegetable oil (vegetarian to vegan) which would be like a softfork.

... just found an english (but shorter version) of the restaurant story here:

Do you know more analogies?
9  Bitcoin / Bitcoin Discussion / Material on Bitcoin (incl. Blockchain) for education on: September 25, 2017, 08:02:33 AM
I am looking for material (slides, infographics, demonstrators) for educational purposes in the field of Bitcoin and Blockchain. Do you know any good ressources?
10  Bitcoin / Hardware wallets / Ledger Nano S supports Segwit on: August 26, 2017, 05:16:04 PM
Ledger releases Segregated Witness support:
11  Local / Presse / [2017-08-20] Kursexplosion bei Bitcoin Cash on: August 20, 2017, 03:56:57 PM
Kursexplosion bei Bitcoin Cash:
12  Economy / Micro Earnings / Comictelegraph Contest on: August 18, 2017, 12:02:11 PM
Contest of Cointelegraph where you are able to collect Satoshis:
13  Local / Altcoins (Deutsch) / Übersicht Altcoins gesucht on: August 06, 2017, 12:35:16 PM
Ich bin auf der Suche nach einer Übersicht der wichtigsten Altcoins.

Die Übersicht sollte zu jeder Coin/Token folgendes beinhalten:
- Kurze Beschreibung der Coin (Ziele, Vorteile, Alleinstellungsmerkmale usw.)
- Kurze Beschreibung zum Team und Entwickler (Wer, wieviele und wie aktiv)
- Wie groß ist die Anwenderzahl
- Marktkapitalisierung

Es müssen natürlich nicht alle Altocins dargrstellt werden, aber immerhin die wichtigsten ersten 20 oder 50 in Bezug auf Funktion, Marktkapitalisierung und Bekanntheit.

Bisher hatte ich bei Coingecko einige Infos gefunden, aber leider auch noch nicht alles.
14  Alternate cryptocurrencies / Altcoin Discussion / Comparsion Chart for Altcoins on: August 05, 2017, 12:21:04 PM
Is there any comparison chart for altcoins available? The comparison chart should include features (e.g. anonymous, speed, transaction costs, security etc.), proof-of-work / proof-of-stake or whatever. In addition, there should be information on marketcap, number of users/devs and activity of the devs.

By now I just found coingecko - which give some details on marketcap, number of users/devs and activity of the devs etc. but not a concise description on the features.

The list does not to have detailed information for each coin, but at least on the most importance ones - in terms of marketcap and/or interesting features.
15  Local / Presse / [2017-08-03] Bitcoin Cash on: August 03, 2017, 06:24:15 PM
Bitcoin Cash: Neues Kryptogeld mit Kursexplosion nach Abspaltung
16  Local / Presse / [2017-07-24] Cointelegraph: DASH in Apple's App Store zugelassen on: July 24, 2017, 10:03:13 AM
Apple hat Dash offiziell als digitale Währung für ihren App Store zugelassen.
Hierdurch ist der Kurs gestiegen. Neben Dash können im App store auch folgende Kryptowährungen genutzt werden:
Ethereum, Bitcoin, Steem, Litecoin, Lisk und Ripple.

Link zu Cointelegraph (Englisch):
17  Alternate cryptocurrencies / Altcoin Discussion / Proof of Usefulness? on: July 04, 2017, 06:32:30 PM
Bitcoin (and other altcoins) spends huge amounts of electricity just to solve a riddle. The result is (beside the creation of the block) not useful at all.
Is there any altcoin/token where the "miners" have to compute something which has any kind of use? Perhaps calculating prime numbers or sequencing a genom or verify something?

Perhaps I am totally wrong and this is not possible - perhaps there is already somehting implemented like this ...
18  Alternate cryptocurrencies / Altcoin Discussion / Number of users of all coins on: July 02, 2017, 09:00:04 PM
Does anybody have a rough estimate how many users exists of all coins (Bitcoins plus all Altcoins)?

I know nobody knows the exact value - but is there any estimation on this?
19  Local / Treffen / Bitcoin/Altcoin Interessierte in Bremen on: June 27, 2017, 08:52:35 PM
Gibt es Personen in Bremen die an Bitcoins und Altcoins interessiert sind und ggf. Lust auf Treffen oder losen Kontakt zwecks Erfahrungsaustausch haben?
20  Alternate cryptocurrencies / Altcoin Discussion / ICO Pool on: June 22, 2017, 09:47:35 PM
The last days we had Status ICO (pain in the neck due to clogging the Ethereum Blockchain) and Civic (queue system).

I thought about having a kind of pool where several investors joins in for a certain ICO. This ICO pool could invest as a whole into a new token/coin and later the tokens/coins will be distributed accordingly.

Perhaps there is already something like this available?
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