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21  Bitcoin / Project Development / BitPay equivalent as script collection - possible? on: April 17, 2013, 02:17:56 PM
I'm still wondering if it is feasible to do the following:

Instead of signing up with BitPay, emulate their way of operating by signing up on some exchanges, depositing some USD and BTC on each and use their API to automatically trade.

Once the payment API gets included in the bitcoin clients it should then be possible to accept bitcoin payments like this (e.g. a 100 USD payment with ~100 USD/BTC prices):
1) get current market average, add a few % for slippage - in this case request 1.05 BTC from the client and a payback address.
2) put a market order for 100 USD on the cheapest exchange - fees and etc. included it costs you 0.99876521 BTC
3) mark the payment as confirmed in your system
4) send back the 0.05123479 BTC change to the user and the 0.99876521 BTC to the exchange to top up the exchange account.
5) mabye even send a signed statement to the user that you exchanged at 0.99876521, so he knows which rate was actually used.

You'd only have to pay BTC network + exchange fees and users might have to trust you with a slightly higher amount than they need to pay for a minute or so. The whole script etc. can be open source, all secrets you'd need to enter would be deposit addresses for exchanges + API keys. For merchants selling BTC it could work the other way round as well, though you might need coloured coins or Ripple to automatically track irreversible USD transfers.

There is already a library in the works that combines APIs from several exchanges. Am I missing something or is the missing thing really just some glue between already existing parts?
22  Bitcoin / Project Development / Bitfinex.com lending interest tracking sheet on: April 12, 2013, 06:27:43 PM
I guess it makes it a bit easier and visible if I share this in a seperate thread as well:

As I track my earnings from lending out USD and BTC on bitfinex.com and I like numbers, I created the following spreadsheet + charts on Google docs:
https://docs.google.com/spreadsheet/ccc?key=0AjDrki5tpdL3dFlYaU53cVozazJiYWo2S1ZQMHZiRWc#gid=5

It is filled with bogus data, but it's anyways to be used as template by you, simply create a copy yourself, delete the explanation sheet (after reading it) and enter your own data.
I hope this helps a few people to better track their earnings and maybe there are even some improvements to be made on this (eventually for example I plan to have some kind of ledger sheet and then weekly/monthly/yearly reports + charts) that I didn't think of yet.

As usual: No warranties, don't start plotting your plan on world domination with this sheet and always stay a bit critical towards stuff posted on the net!


Edit:
Changelog:
2013-04-12: Initial release
2013-04-12: Added IFERROR() statements in columns G-J, thanks superbit! (https://bitcointalk.org/index.php?topic=119745.msg1822082#msg1822082)
23  Bitcoin / Bitcoin Discussion / Social Network "Zurker" now accepting Bitcoin (through Coinbase) on: March 14, 2013, 09:27:42 PM
http://www.zurker.eu/update-1-115

Quote
Zurker Now Accepts Bitcoin


Zurker is pleased to announce that we now accept Bitcoin payments for credit purchases.

Bitcoin is a decentralized currency which governments have no control over. It is private and secure, and cannot be frozen or limited. Bitcoin is becoming more and more mainstream, with hundreds of millions of dollars worth of transaction occurring annually. If you don't have a Bitcoin wallet, you should get one now.

Several startups are facilitating Bitcoin transactions. We are currently using Coinbase.

If you don't know what Bitcoin is, here's an introductory video, and here's a great article, and here's the Wikipedia entry.

To purchase vShares using Bitcoin, just head on over to the payment page and select "Bitcoin" instead of "PayPal" when checking out.

Well, not facebook (yet?), but it's something! Smiley
24  Economy / Securities / Checking for interest: Bitfinex lending fund on: March 13, 2013, 11:12:43 PM
Another idea of mine, that might give relatively small but relatively well secured payouts:

Lending BTC on Bitfinex.
Bitfinex is an option platform offering amongst other things to open an account and lend out BTC or USD deposits to its users who want to do leveraged trades. Even though the interest is usually lower than what traders can/do(?) earn, the interest is guaranteed and secured.

I'd like to offer to open a fund in BTC which get deposited to Bitfinex and pay out interest to its members periodically (interest on Bitfinex is credited daily).

Current numbers from lending out BTC show quite jumpy returns (in 14 days I had 1 day with 0 interest and 2 days with more than 10% APR - averaged over that timeframe I'm at ~3% APR) which are of course higher if the USD price falls (or trader think it might fall), as people borrow BTC to sell them and buy more later at cheaper prices.

As interest compounding is actually quite a nice feature of Bitfinex (since it is paid daily, I already have ~0.1% more funds to lend out and I gain interest on these as well already) I'd probably look for people who don't want daily dividends or something like this - it would anyways only create bitdust. Maybe a payment once a certain treshhold in interest has been reached? Also withdrawals are not immediate at all, on one hand you can of course only withdraw coins that are not currently actively lent (d'oh!) and also Bitfinex has all coins in offline storage and processes withdrawals on business days, so it might take a while (= up to a few days if you request a withdrawal on friday before easter for example) until a request is processed. This fund should be viewed as long term investment, not for day trading.

Potential risks mainly include Bitfinex going bankrupt (unlikely due to trading activity as they get a cut on every trade, unlikely as well due to being hacked as BTC are supposedly stored offline), MtGox going out of business suddenly and taking Bitfinex' money with them (which would not be Bitfinex' fault but still I guess they have quite some funds over there to execute the user's trades) and me scamming you willingly (Kiss) or unwillingly (e.g. I die + destroy my phone with the GAuth key in the process and don't have a dead man's switch in place).

Your benefit over lending directly at Bitfinex is that you don't need to set up and secure an account over there, as you can participate in the whole thingie here just by submitting BTC and an address that will be used as payout address, your "alias" in reports and to sign any payout requests. Also you get nice stats/graphs done by me.

My benefit from all this would be that I gain a part of the interest generated (5% seems like a reasonable amount) and that I didn't create all my nice statistics and graphs just for myself.

If you are generally or especially interested in something like this or have found a major flaw in my idea, please feel free to let me know in this thread! Smiley

tl;dr: Interested on earning a few meager % on a relatively conservative investment? Express your interest in this thread!
25  Bitcoin / Development & Technical Discussion / Python brainwallet generation - hash160 problem on: March 10, 2013, 12:00:31 AM
Code (Python 2.7):
Code:
import hashlib

passphrase = ""

hash160 = hashlib.new('ripemd160')
hash160.update(hashlib.sha256(passphrase).digest())
print hash160.hexdigest() #<-- b472a266d0bd89c13706a4132ccfb16f7c3b9fcb

print hashlib.sha256(passphrase).hexdigest() #<-- e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

I want to perform steps 2+3 from https://en.bitcoin.it/wiki/Technical_background_of_Bitcoin_addresses

The hexdigest of the sha256 hash is the correct one for an empty input.
According to https://bitcointools.appspot.com/?s=&r=1 hash160 however should be b5bd079c4d57cc7fc28ecf8213a6b791625b8183, not the one I came up with.

https://github.com/weex/addrgen/blob/master/addrgen.py from line 71 on does exactly the same thing I do here (just outputting the digest, not hexdigest) and does call the result from this "hash160" later in the code. Where/what is my error?!
26  Economy / Auctions / Get 1 BTC penny auction style (a bit different, please read rules) on: February 18, 2013, 03:03:30 PM
As a test for an idea I had, I want to propose (and conduct) the following auction system:

You can send bids of at least 0.01 BTC in up to 8 decimal digits of precision to the following address to win the 1 BTC deposited there:
1FHEiDZtMnWg6DtsaFGuT6DKUNadhjH6Ct
(https://blockchain.info/address/1FHEiDZtMnWg6DtsaFGuT6DKUNadhjH6Ct)

The winner however will NOT be the person who bids the highest and also not the one who bids lowest - to win, you need to bid as close to 125% of the average of all valid bids as possible.

An example:
The average bid amount of all valid bids is 0.01337 BTC.
0.01337*1.25 = 0.0167125, so whoever did bid closest to that amount is the winner.

In case several people who bid exactly the same amount would win, the transaction who got into an earlier block wins. In case it's even the same block, the one with the higher fees paid to miners wins (yay miners!). In case this STILL doesn't break the tie, the lower transaction ID wins (to have some slightly arbitrary "coin flip" event - I hope it's enough randomness for a 1 BTC penny auction...).

Please make sure to send bids ONLY from addresses YOU control, similar to gambling on satoshi's dice. A lot of people will probably NOT win the BTC auctioned off and get back their bid, so be prepared for that.

You can place as many bids as you like until the next retarget (at block #223776), all transactions included in blocks until then (above 0.01 BTC) will be considered valid bids.
Every transaction counts as seperate bid, so having a 0.01 BTC bid and bidding 0.05 BTC after that means you have 2 bids (0.01 BTC and 0.05 BTC), not 1 (0.06 BTC).

Fees:
I take a flat fee of 0.005 BTC off every bid, no matter how high it was initially and I'll keep 100% of the winning bid of course. Also I keep 100% of all bids below 0.01 BTC as punishment for not reading. The rest of the bids will be returned to the address they came from (if several addresses are involved combining unspent outputs, I'll just send it to one of them). I'll pay any transaction fees the network might require and I'll use the blockchain.info "sendmany" implementation for that.

Transactions that come in late (after block #223776) but before I returned all loosing bids will also be returned after having the fee deducted, but they won't be used in the calculation of the winning bid and they also can NOT win. If somebody sends BTC AFTER I reimbursed all bids, I consider this a donation and a token of appreciation and you will NOT be reimbursed at all.

After the block #223776 has been mined, I'll publish the outcome and stats and start paying back bids as well as the winner.
I'm human, errors can happen and this is not an automated process, so please be a bit patient after the block has been mined to let me triple check everything. I'll try to be as fast as possible (I expect a payout after max. 24 hours), but please don't expect to get your bid back already in block #223777.
Also this is an experiment, I know that I'll loose a bit of money if less than 200 bids are entered (which, given the "popularity" of this subforum is already a bit risky) but that's ok. I'm rather interested if people actually like the idea enough to bid and how high they bid and I think that fun is worth the time and 1 BTC.

As editing is not possible here, I'll probably post from time to time the current averages and other stats to keep the thread afloat. Also feel free to comment (please stay on topic) as well as announcing your guesses here (of course, only what's in the block chain ultimately counts).

Happy bidding and may your guess be the best! Smiley
27  Local / Deutsch (German) / Bitcoin mining Botnet untersucht (nach 7(!) Monaten) on: December 11, 2012, 10:50:44 AM
Siehe News auf Heise und Golem:
http://www.heise.de/newsticker/meldung/Botnetz-versteckt-sich-im-Tor-Netzwerk-1764791.html
http://www.golem.de/news/skynet-botnetz-wird-via-tor-netzwerk-per-irc-gesteuert-1212-96261.html

Originalquelle:
https://community.rapid7.com/community/infosec/blog/2012/12/06/skynet-a-tor-powered-botnet-straight-from-reddit#

Der (höchstwahrscheinlich österreichische, obwohl die "Forscher" an "german" glauben...) Operator hat sogar vor über einem halben Jahr auf Reddit ewig lange Antworten gepostet:
http://www.reddit.com/r/IAmA/comments/sq7cy/iama_a_malware_coder_and_botnet_operator_ama/?limit=500

Was ich mich nur frage: Ist mining über TOR hidden Services echt sinnvoll?! Gerade bei Blockwechseln ist die Latenz doch von Bedeutung... nachdem der Operator aber nichts für Strom zahlt und sowieso mit verminderter Leistung arbeitet könnte es ihm auch einfach egal sein.

Interessant finde ich es auch, dass anscheinend keiner versucht hat mal mit BTCguild zu reden. Ein single-miner mit hohen invalid-Raten und periodisch schwankender Leistung sollte doch nicht SO schwer zu finden sein?! Mir ist es allerdings egal und ich verdiene auch nix damit, wenn der hopsgenommen wird, wer sich da reinbeißen will hat aber wohl alleine schon über Reddit genug Anhaltspunkte, das Ganze dann noch mit BTCguild und anderen Pools kombinieren und man findet sicher das eine oder andere Botnetz.
28  Bitcoin / Development & Technical Discussion / Aggregating addresses to wallets (using armoryengine) on: July 04, 2012, 10:59:53 AM
Since there's currently a lot of fuzz about pirateat40's operations (is it a ponzi? is it legit? where does he get his coins from/back, if he really sells them OTC? how is GPUMax fitting in?), I think one of the best ways to analyze the situation is to get an address that surely belongs to him, hope for combined inputs if he sends something from that address, assume these belong to him as well (as he'd need to have private keys for that) and work our way from there until we have all linked addresses to a single bitcoin address.
Also something like this might also be useful for other purposes and I haven't found many projects concerning this (one would be toolongdidntread.com)...

After that, we can assume this as his wallet and check the balance, money flows etc. (which is currently a bit beyond what I did so far).

The first problem I ran into however is:
Is my code so far really correct? I don't want to make accusations or draw conclusions when it turns out that I included an MtGox address out of stupidity...

Anyways, here's the code to track any address (supplied in the "trackaddr" list) for multiple inputs. It will iterate over the whole blockchain multiple times until no more new inputs are found. Because of recent blockchain spam, I limited it currently to block 160000 (enough for the address I have so far) and there's probably a nicer way than running ~10 times over the whole chain. I have a fast CPU however, so it doesn't really bother me atm, the bigger concern is if it is really doing what it's supposed to do and has no chance of picking up and including some random other addresses.

Code (with Armory's donation address up to block 170000):
Code:
from armoryengine import *

BDM_LoadBlockchainFile()

topBlock = TheBDM.getTopBlockHeight()

trackaddr = ['1QBDLYTDFHHZAABYSKGKPWKLSXZWCCJQBX']
taintedblocks = []

addratstart = len(trackaddr)
addratend = 0

iterations = 0
transactioncount = 0

while addratstart != addratend:
  transactioncount = 0
  iterations += 1
  addratstart = len(trackaddr)
  for h in xrange(0, 170000): #topBlock+1):
    if h%10000 == 0:
      print '\tScanned %d blocks' % h
      print 'Found %d addresses so far.' % len(trackaddr)
    
    header = TheBDM.getHeaderByHeight(h)
    txList = header.getTxRefPtrList()
    for tx in txList:
      foundaddr = False
      for nin in range(tx.getNumTxIn()):
        txin = tx.getTxInRef(nin)
        try:
          senderAddr20 = TheBDM.getSenderAddr20(txin)
          address = hash160_to_addrStr(senderAddr20)
          #print address
          if address in trackaddr:
            foundaddr = True
            print "FOUND TRANSACTION! At block " + str (h)
        except:
          pass
      if foundaddr is True:
        for nin in range(tx.getNumTxIn()):
          txin = tx.getTxInRef(nin)
          try:
            senderAddr20 = TheBDM.getSenderAddr20(txin)
            address = hash160_to_addrStr(senderAddr20)
            trackaddr.append(address)
          except:
            pass
        trackaddr = list(set(trackaddr))
        transactioncount += 1
        taintedblocks.append(h)
        taintedblocks = list(set(taintedblocks))
  addratend = len(trackaddr)

print trackaddr
print taintedblocks
print "Went through the blockchain %d times!" % iterations
print "Found %d transactions" % transactioncount
print "Found %d blocks where these transactions were included" % len(taintedblocks)
print "Found %d addresses" % addratend

Oh, and I won't post any results (it's easy with armory to include all found addresses to a "wallet" for example and read the spendable balance of that at each block) publicly or in PMs until I have verified this code to be correct! Also pirate seems to be quite paranoid about posting bitcoin addresses belonging to him, so good luck with finding some (unless you're a customer at BTCS&T, then you can of course use your deposit address).

Edit:
I was using armory 0.76 rc1 - the current 0.81 version throws:
Code:
Traceback (most recent call last):
  File "!findwallet.py", line 29, in <module>
    for nin in range(tx.getNumTxIn()):
  File "xxxxxxxxx\Armory_0_81\CppBlockUtils.py"
, line 813, in <lambda>
    __getattr__ = lambda self, name: _swig_getattr(self, TxRef, name)
  File "xxxxxxxxx\Armory_0_81\CppBlockUtils.py"
, line 51, in _swig_getattr
    raise AttributeError(name)
AttributeError: getNumTxIn
29  Economy / Securities / [GLBSE] Weighted average price for a 1 MH/s bond is below 30 bitcents on: June 05, 2012, 09:07:40 AM
I wrote a script that does the following:

Take last trade price (as not all assets always have a 24h or 5d average price and spread between bids/asks is sometimes high), multiply by the amount of shares that were paid in the latest dividend payment and by the MH/s that the bond claims to pay out. Then calculate the average out of this.

Result (unordered):
Code:
YABMC GH/s: 47.278 market value (in BTC): 13705.8922 average value of 1 MH/s (in Satoshis): 28990000
PUREMINING GH/s: 10.0 market value (in BTC): 3900.0 average value of 1 MH/s (in Satoshis): 39000000
007 GH/s: 0.656 market value (in BTC): 189.584 average value of 1 MH/s (in Satoshis): 28900000
JAH GH/s: 2.5 market value (in BTC): 775.0 average value of 1 MH/s (in Satoshis): 31000000
TYGRR.BOND-A GH/s: 2.024 market value (in BTC): 586.96 average value of 1 MH/s (in Satoshis): 29000000
GIGAMINING GH/s: 100.0 market value (in BTC): 29687.5994 average value of 1 MH/s (in Satoshis): 29687599
ZETA-MINING GH/s: 7.0 market value (in BTC): 2029.99993 average value of 1 MH/s (in Satoshis): 28999999
BITBOND GH/s: 92.4 market value (in BTC): 26400.0 average value of 1 MH/s (in Satoshis): 28571428
total GH/s: 261.858 total volume (in BTC): 77275.03553 average value of 1 MH/s (in Satoshis): 29510282

Weighing the average above means for example, that the price of the 100 GH/s of gigamining have a much higher influence than the 2.5 GH/s of JAH

Some bonds haven't paid any dividends (or even shares - CANMINE...) yet, so it's impossible to see how many shares really have been distributed already there. These are excluded.
OBSI.1MHS is not part of this, as their payout formula is not comparable to real PPS shares.
For MOORE I'd need a bit of code still to calculate how many weeks have passed since they issued to get their current hash rate.

Mining "companies" are next on the list, they might require some different measurements though and some important numbers are not available on GLBSE, like how much the assets of the company are worth, how high their income/expenses are... so I likely can only compare dividend payouts.

This is fully automated, all you need to do is run the script again and (if a new mining bond shows up) eventually add a line with ticker symbol + hash rate per bond.

30  Economy / Goods / Diablo III guest passes for donation [both taken] on: May 24, 2012, 02:09:24 PM
Here are 2 Diablo III Guest pass keys:

Code:
B_6JPR - YZTY - X2RYJ7 - GP_8 - 8EXE2H
JTPD_K - 26WH - R_PJR_ - 87BZ - GGXBME

If you used one of them, please tell here in the thread so others know. It would be cool if you give me a tip of any amount to 1u774EAK5PSEhvMzKLURBFtjhJqQUpb6r, but in the end it's up to you. I just don't like selling stuff that's supposed to be free...

Instead of _ please write the number four, this is just to make it a bit harder to copy-paste and to make sure you actually read the rest of the posting. Wink

Oh, and I only had these 2, so if they are gone, that's it. Maybe someone else wants to give their's away as well here?
31  Economy / Securities / [soon on GLBSE?] brendio to pirate pass through - up to 6.79% on: May 21, 2012, 01:04:56 PM
As brendio was quite interested in raising his pirate account to higher tiers (https://bitcointalk.org/index.php?topic=82572.msg911809#msg911809) I thought of the following concept:

Pirate pass through shares traded on GLBSE, pirate account by brendio, management of GLBSE operations by me. I'll take a 3% cut on the dividends for trade fees (e.g. filling buy offers costs 0.5%) + time invested, so in a 7% account scenario it would pay out 7 * 0.97 = 6.79% per week.
Brendio however said, he would only pay the 7% for the first 1700 BTC invested and 6.75% for BTC deposited after that, so we'll have to see about that. Mathematically, it can be simply treated as a slight decrease in interest on pirate side, but even in the worst case (millions and milions of BTC at 6.75 so the 1700 with 7% don't really matter any more) it still pays out better than any other 1-week pirate pass through bond on GLBSE: 6.75 * 0.97 = 6.5475%. The average case should be something in between.

Intended share price:
1 share = 1 Bitcent (0.01 BTC) to allow people with a few mining bonds to reinvest their earnings. Also I like to have more liquidity.

Outline of terms (to be feedbacked) in "prose":

Every Sunday there will be the dividends for the last week (the ones pirateat40 pays on monday). To clarify, I pay the dividends from the 1st-7th on the 14th while brendio receives them on the 8th, so he has a few days buffer to transfer them to GLBSE.
Every share receives the interest as dividend via GLBSE (minus GLBSE fees, if any get introduced there). To receive the dividend, you need to hold the share at the time the dividend is paid, there's no way currently to track if somone held a share for say 6 out of 7 days.
After the dividend payment on Sunday, all outstanding bids of 0.01 BTC or higher receive new shares. The money from this sale then is transmitted to brendio and put by him into his savings account asap.
I'd love to sell shares more often or just put up a huge bidwall, but there might be problems with dilution and it would be too hard to sell shares again if you don't want them any more.
Since pirateat40 seems to calculate interest by the minute(!) there might be some slight inconsistencies (especially once interest on brendio's account increases or decreases) - so the final dividend will simply be:
( Brendio's total interest of the week * fraction of pass-through money in his account (e.g. 3/4) ) * 0.97 (the 3% cut)

If pirateat40 lowers or increases the interest on brendio's account, everything stays the same, just the interest gets increased or decreased on shares too (and my 3% of the interest is worth more as well). To hit the 7% weekly, this asset needs to sell 170000 shares worth 1 bitcent each (or 1700 BTC worth of shares), until then rates are as displayed in pirate's thread. After this amount is reached, there will either be a motion or a discussion here how to continue - or maybe brendio even decides to continue paying 7% to the fund as well, since he hopefully won't have a lot of hassle with all of this anyways.

As always with pirate investments, one of the first questions coming up would be: "How do I get out?!". On one hand, you can of course fill the ask spots on Sunday yourself, when I try to raise new capital, on the other hand you can also request a payout at a 5% fee. You'll have to transfer the shares back to me for this and won't receive dividends for that last week (obviously). I'll then ask brendio to withdraw the proper amount of BTC from pirate and transfer these asap to the GLBSE account where the share transfer originated from. You'll then receive 0.0095 per share sold this way, the 0.0005 BTC fee will most likely go to brendio and me (+ GLBSE for fees) - I haven't talked to him about that yet though so this is subject to change.

Another question that might be important:
Why should I trust you and will you verify with GLBSE?
You should trust nobody on the internet and no, I won't verify with GLBSE for the simple reason that I don't want my personal data floating somewhere on a server/HDD in the UK or US. If you really think I'll take the money and run, well then simply don't invest here. I don't know brendio in person either, neither pirateat40. All I'm offering is a little bit of convenience and I also tried to keep share prices low enough that you don't have to put up hundreds of BTC just to see if I would steal them from you or not. Most of the time the money anyways will lie at pirateat40's accounts, so you should rather ask yourself if you trust him and his operation.

I plan however to publicly release the following information that can be verified with the blockchain (the blockchain never lies!!!11):
* An address to the GLBSE account of this asset to be used by brendio for dividend payments
* An address to the GLBSE account of this asset to be used by brendio for withdrawn money (e.g. someone want to withdraw 100 BTC and sends 10000 shares - then brendio would send the 100 BTC to that address after getting the coins from pirateat40 for everyone to see. This also means that you can withdraw quite in silence and anonymously)
* TX hashes of:
  # The sunday payments to brendio to be deposited to pirateat40 (or, if I get a direct deposit address to pirate, then the TX hashes to this account)
  # The TX hashes of dividend payments from brendio to the dividend GLBSE address (a bit redundant, I know)
  # The TX hashes of withdrawal payments from brendio to the withdrawal GLBSE address (this can as well already be seen on blockexplorer by knowing the address)

What if pirate defaults and brendio won't get paid or only gets a fraction of the deposit back? - Well, in this case the shares will simply be bought back for either 0 BTC or the fraction that brendio got per piece and the asset is dead.

All in all I want to offer a service that I would like to see: Low fees, long time forum members, always a chance to cash out, high return rates, clear terms and low share price for liquidity.

The "real" terms will be worded a bit more strictly than what's written above, but contain in essence the same things.

Do you have any feedback?
Would you buy such shares?
Is there something that I overlooked (unfair advantage, too much work for me or brendio in case of X or too high a risk for doing Y...)?
Please comment (in a civil way) below and let me hear your ideas.
32  Local / Deutsch (German) / Vortrag auf TU Graz über Bitcoin on: May 17, 2012, 07:23:03 PM
Habe gerade einen Vortrag auf der TU Graz (Österreich) über das Thema Bitcoin in der Vortragsreihe "GADI" (Gesellschaftliche Aspekte der Informationsgesellschaft) gefunden, Aufzeichnung unter:

http://curry.tugraz.at/portal/1/watch/502.aspx

Viel Spaß beim Anschauen + Diskutieren!
33  Bitcoin / Development & Technical Discussion / Blockchain based stock exchange on: April 19, 2012, 01:07:31 AM
Since there was a discussion recently in the general forum about GLBSE + anonymous networks, I had another idea how to do share trading in a bitcoin style block chain:

1) Build a "share chain" similar to the p2pool one with blocks on average every 10 (or rather 30...) seconds.
2) Every 2nd block is a special block (by protocol design): It contains (PGP signed) the header of the block before and has difficulty 1. This adds a point of centralization, as only the PGP key(s) of the exchange would be allowed/accepted to sign this block's content. Future blocks of course then have to build upon this block. Difficulty 1 is enough for this, as it is a forced block anyways and a small FPGA machine or so in a corner of the room would be enough for the exchange to maintain + operate as mining equipment (they can output a new diff1 block in a few seconds).
3) Conflicting orders can be decided by attaching transaction fees to your orders - or just firing up a miner and crunching that block yourself with your order in it instead of the other guy's. This might provide additional income for miners.


1) Ensures that transactions get into blocks reasonably fast
2) Ensures that after you see the signed block, you can be sure that your transaction is in the major chain. Also it means the system can't be reversed as soon as a new key block is released.
3) I'm not 100% sure about this one, but there's definitely a need to decide between conflicting orders - and "first in - first included" might not always work or be the most sustainable solution, considering that in New York there are whole buildings bought just because they are closer to sea cables and might save a few microseconds to get data faster for algo-trading. This is CRAZY and unsustainable, especially for a global stock exchange (currently someone based closer to e.g. GLBSE would have better pings = better trades. This is just unfair imho.)


Did I overlook some major issue? Please post some feedback! Smiley
34  Economy / Services / [10 BTC reward *paid*] Guide to install DSpace on Amazon EC2 on: April 13, 2012, 12:04:03 PM
As I'm currently struggling with a task for a project of mine and don't want to waste any more time on fighting the Amazon Linux command line, here's my deal:

As soon as I get from you:

* A step-by-step/command-by-command instruction how to create a running DSpace installation on a Amzon EC2 Micro instance using a fresh, naked + empty 32 or 64 bit Amazon Linux AMI with SSH access and assuming "ec2-user" just being logged into a virgin machine for the first time as the starting point. This guide should be posted here in the open, in case you think it might need some polishing but you don't want potential competitors copying your work, you can also send me links to google docs or so via PM - after the task is done however, I will publish the guide here and hopefully also on the DSpace Wiki.
* A bitcoin payout address

until 15.4.2012 (23:59:59 GMT... Wink )

I will send you 10 Bitcoins to that address. If the guide is really well written and/or the task is really quickly fulfilled (like still today for example) and/or also takes care of potential risks for live deployment (something like "choose a good password here, this can be accessed via a web interface too!"), I also consider a bonus.

I reserve the right to first try out your solution, also please keep in mind that just writing "do this, that and then follow the main guide" is NOT enough for me. Basically I want to be able to put every command one after the other just in a shellscript and after that script is done, DSpace is running (except for some changes with vim/nano in config files or so - but I think you get the idea). As a rule of thumb, no "enter the basic config information and continue" - explicitly write what goes in which config file.

About the software to be used:
DSpace: http://www.dspace.org/
Amazon EC2: http://aws.amazon.com/en/ec2/
Besides setting up DSpace, you'll likely also need Apache Tomcat, Apache Maven, Apache Ant and a Postgres-SQL database set up with at least some basic settings, so it is possible to run/access the DSpace software package.

Some starting points:
DSpace Deployment on EC2:
https://wiki.duraspace.org/display/GSOC/Amazon+EC2+DSpace+Deployment (<-- an example for a "guide" that is NOT enough... Angry )
General DSpace installation guide:
https://wiki.duraspace.org/display/DSDOC18/Installation
Amazon Linux is by the way generally quite similar to RedHat/CentOS, in case you're wondering. Also if you don't have access to Amazon EC2 yet (but are a better Linux admin than me) and want to do this, there's a whole year of free operation included in Amazon's services, so you likely won't have any costs besides your own time doing this task.

Any questions? Feel free to ask, preferrably here in the thread.
35  Local / Biete / [Verkaufe] nVidia GTX260 on: August 24, 2011, 11:54:10 AM
Hallo zusammen!

Ich biete hier eine gebrauchte Palit nVidia GTX 260 mit 216 Shadern an.
Das Modell ist dieses hier: http://geizhals.at/eu/412935

Vorgestellt hätte ich mir einen Preis von etwa 75 EUR + Versand (aus AT) wobei ich aber auch für (sinnvolle) Gegenangebote hier im Thread offen bin.

Gebote bitte in EUR, Bezahlung in BTC; Umrechnung erfolgt dann laut dem bei Zusage aktuellen 24h gewichteten Mittelwert für EUR auf http://bitcoincharts.com/markets/
Solltet ihr auf Vorabversand bestehen, würde ich allerdings mehr Daten einfordern (z.B. Ausweis + Zettel mit "custom" Phrase) als wenn ich zuerst in BTC bezahlt werde. Generell bevorzuge ich Vorkasse.

Zum Mining ist die Karte jetzt nicht wirklich geeignet, aber es gibt ja angeblich auch noch andere Verwendungsmöglichkeiten für GPUs... Wink

Referenzen habe ich auf Anfrage mit einem (selten genutzten) eBay Account und auf Hardwareluxx.

Generell:
Privatverkauf, daher keine Gewährleistung meinerseits. Zwecks Garantie müsste man sich an den Hersteller wenden - ich werde versuchen noch die Originalrechnung aufzutreiben, kann da aber nichts versprechen, daher derzeit ohne Rechnung im Angebot.
36  Other / Off-topic / Efficacy of colloidal silver on: July 29, 2011, 03:36:48 AM
Edit:
I did NOT start this thread, it was ripped out of context and given a misleading title by theymos (https://bitcointalk.org/index.php?topic=33345.0), something I do not agree with, by the way.
Originally it was an answer to a thread by tecshare that was very similar to https://bitcointalk.org/index.php?topic=32199.0

***** end of edit *****


Just a few links to consider:

Possible side effect:
http://en.wikipedia.org/wiki/Argyria

Esowatch, German:
http://esowatch.com/ge/index.php?title=Kolloidales_Silber

On the other hand, sea water contains between 2-100 ppm silver, so this stuff might not be really that dangerous. To consume 12 ppm silver you might also just enjoy some nice freshwater fish, it has about the same concentration of silver... and probably tastes better.
37  Economy / Trading Discussion / Tradehil referrals: How much have you earned? on: July 26, 2011, 01:12:13 AM
I am just kinda curious, how much others have earned with their Tradehill referrals and what you do with them.

As I always hate threads that start like that without the thread starter also showing his earnings, here are my stats:

Number of Users Referred: 224

Your Earned Commissions
AUD   0.0013... AUD
EUR   0.05... EUR
LR   0.36... LR
USD   22.2... USD
(I'm still missing some INR and CLP... Wink )

I usually just convert my ref income everytime I hit ~1 USD to BTC and once I hit 1 BTC, I pull it over to my wallet.

Interestingly 1 ref'ed user is worth nearly exactly 10 US cents (until now, after 1 1/2 months) or a bit less than 1 Bitcent - do some of you have different experiences? Did it "pay off" yet, to pay some ppl to take your refcode (like some did in when TH started)?

Unfortuantely it seems like I can't turn off my signature here: I do NOT want to seem like one of these stupid refspammers who just open meaningless threads to show their reflinks - I am really interested in the topic!
38  Alternate cryptocurrencies / Altcoin Discussion / Hoarding NMC now? on: July 12, 2011, 10:18:16 PM
Namecoins will most likely drop in difficulty significantly in ~1 week. (http://dot-bit.org/tools/nextDifficulty.php)

Might it be useful to buy namecoins right now and speculate on a second NMC bubble or not?

/discuss
39  Bitcoin / Project Development / [Idea] Use mining shares instead of Bitcoins as micropayments on: June 20, 2011, 11:32:05 AM
First I wanted/started to write something about distributing Bandwidth via proof-of-work units (aka. difficulty 1 Bitcoin mining shares) and financing traffic with these, but I think this can be even more generalized:

A lot of people would like to do some micropayments (for buying farmville carrots or whatever), but Bitcoin is not exactly tailored for transactions this small. Also users would need a fully fledged Bitcoin installation + some way to get Bitcoins in the first place, which they might not want to do for whatever reason(s).

The worth of a single 1 difficulty share is [current average worth of 1 bitcoin block] / [current difficulty] which currently would mean a share equals 50.01/877226.66666667 = ~0.000057 BTC.
If difficulty goes up more, this value will go down further, as the reward per block goes down (I don't expect transaction fees to go up THAT much that a single block on average still will be worth more than 50 BTC like currently EVER), the value per share goes up again.

This means micropayments of very small sizes are easily possible using OpenSource tools (= Bitcoin mining programs) and can even be done via the browser (via WebCL miners like Kradminer or Java miners - Javascript mining is too slow though I fear) or any other miner they can think of.
Just enter your hostname, their account name (if there is one required, could be just tracked via IP as well, if it's a "live" setting for getting limited time access to content for example)

Imagine getting 1 Rapidshare credit for every 100 shares you submit instead of BTC or even a completely new one-click hoster that is 100% financed by mining - the more shares you submit, the more bandwidth you get. No ads or other restrictions needed!

Additionally, since you as operator use BTC anyways, you can even sell these "credits" for BTC below "market value" (example: 10 000 credits for 1 BTC which would give you credits "worth" 0.57 BTC) to make users not solely rely on mining (Laptop users...)


Using existing tools like the Bitcoin mining proxy, such a system could be done already today and to reduce variance, you could relay shares from many/all pools and just submit the (verified) results from your users as your own, like the mining proxy does. If the share is then also accepted by the pool, credit the user with 1 unit of whatever you use to track their contribution and there you have it.


Advantages:
* Can be extended with Bitcoin payments and "mining credits" can be sold to users for BTC as well
* No Bitcoin needed AT ALL if your Users don't want it - you can even code your own miner and rebrand it to whatever you want
* Users are keen to generate revenue for you, no way of cheating (proof of work!)
* Users get advantages too for working for you, benefitial for both parties
* no hassle with mining for you, but still income from mining instead of buying at exchanges with volatile rates
* More users, more costs, more income
* Ads and other stuff STILL possible

Disadvantages:
* Users at least are required to run a web applet, if not even a full Bitcoin miner
* Mistrust what "these calculations" really are, as nearly everywhere where I've seen people advertising mining
* If you remain hidden about what you're really doing (see compute4cash who let you mine and pay out ~50% of the USD generated), this can hurt your reputation
* If you rely on income from BTC, potential tax regulation issues (talk to a professional!)?
* Laptop users/users with weak GPUs (nVidia is kinda okay if you don't charge HUGE prices, many still generate 1 or more shares per minute) are either not in your target group or a bit excluded/forced to pay - expect some hate from them
40  Economy / Trading Discussion / ...and BÄM! we have hit the 17 USD mark again on: June 17, 2011, 12:04:57 AM
Interestingly this time it's exactly the other way round: difficulty increases (by quite a bit I have to say!) but price breaks down with panic sales as I post down to 16.60!

What's your prediction?

Will people now invest in Namecoins?
Will the price rebound? (16-17 per BTC is quite attractive to buy imho, gets close to the 10EUR mark!)
Were people preparing (selling @20 in advance to buy cheap now? - It seems like a clear "no" to me...
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