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941  Other / Meta / Re: Using offsite images instead of posting as text. on: May 24, 2014, 03:24:46 PM
Interesting indeed. I don't like to ban nor censor things but I'd have to be neutral on this. If anything but malicious comes out, I don't see a problem.

Well the malicious use would be to delete or alter post history in a way that removes any record.   Once it is used maliciously it is too late.  It is kinda like saying I don't mind drinking and driving as long as the driver doesn't get into an accident.  We should only ban drinking and driving accidents not drinking and driving.
942  Economy / Economics / Re: Why controlling BTC supply is possible on: May 24, 2014, 03:22:06 PM
Well I didn't mean blockchain volume is a "problem" but at some point in the future tx will either be off blockchain or the tx volume demand will be so high that either tx fees are incredibly high (bitcoin becomes more of a high value fund transfer network like interbank wire transfers) and/or the requirements to run a node become so high that the network is run by a handful of nodes.

For example 7 billion people aren't going to be able to pay for their morning coffee with bitcoins, at least not as on blockchain transactions.
943  Other / Meta / Using offsite images instead of posting as text. on: May 24, 2014, 03:18:37 PM
Should this activity be banned?

https://bitcointalk.org/index.php?topic=621411.msg6913184#msg6913184

I can't see a purpose for doing this other than it would allow someone to instantly delete any or all of their posts in the future.   I doubt bitcointalk maintains archives of all linked images so post "history" would be useless for verifying or restoring "deleted" posts.

As a side note it makes quoting a pain in the ass, is just generally disruptive, and makes the contents unsearchable but I am more concerned with the malicious use.
944  Economy / Economics / Re: Why controlling BTC supply is possible on: May 24, 2014, 03:05:01 PM
Bitcoin makes provable reserves possible.  I don't know of any online wallets that use reserve proofs but it can be done.   Some exchanges use this (became a selling point after it turned out MtGox didn't have a full reserve and probably hadn't for years).  There is no reason online wallets can't as well.   Of course provable reserves require users (at least some) to verify the proof is correct (by locating their balance in the reserve tree).  If users don't then it is possible for online wallets (and exchanges) to still cheat.  There are no material difference between an online wallet (that uses a shared wallet) and an exchange when it comes to proving reserves, but I guess users of online wallets have so far not demanded them.  Services like blockchain.info are more like a desktop client in the sense that keys are not shared with the wallet service and users have unique sets of keys.  FRB wouldn't be possible on a wallet like blockchain.info without fraud and that fraud would be very easy to detect.

Another option is multisig where the eWallet has one key and the user has a second key (on say a smartphone) spending coins requires using both keys.  This is more secure than provable reserves as it doesn't require validation and it has the added benefit that the exchange can't get "hacked" or hacked and disappear with all the funds.   However this does mean that all transactions are on blockchain so any benefits of off blockchain transactions are lost (reduced/no fees, instant confirmations, reduced blockchain volume, etc).

945  Bitcoin / Development & Technical Discussion / Re: Early bitcoin mining and unique addresses on: May 24, 2014, 02:45:06 PM
Bitcoin was designed generally assuming addresses would never be reused. A number of the assumptions in the design are broken by reuse— but users are ignorant and lazy and now adays reuse addresses frequently. The reference software does it right generally, so you don't see so much reuse earlier in Bitcoin's history.

What is the benefit of not reusing addresses?

Privacy is one.  Address reuse makes it easier to track transactions on the blockchain.   Also in the unlikely event that ECDSA is compromised or a client has a bug which allows funds to be stolen if the PubKey is unknown not reusing addresses keeps that information hidden until a transaction is made.  An address is an encoded PubKeyHash to spend the coins requires providing the corresponding PubKey.  So even if one could steal coins of all known PubKeys if an address has only been used once the PubKey is still unknown to the attacker.  It is a secondary line of defense and would give the keyholder options for safely transfering funds to a more secure address.

This is more than just academic.  ECDSA signatures require a unique "k" value to be used.  If the k value is repeated for the same PubKey then the private key can be computed and funds stolen.  This happened on android wallets due to a flawed RNG however funds could only be stolen from users who reused the same address.  The flaw existed for all users but those who didn't reuse addresses were safe as the exploit required the PubKey to be known and there to be at least two "spends" from the same address.
946  Bitcoin / Development & Technical Discussion / Re: Early bitcoin mining and unique addresses on: May 24, 2014, 02:39:12 PM
Bitcoin was designed generally assuming addresses would never be reused. A number of the assumptions in the design are broken by reuse— but users are ignorant and lazy and now adays reuse addresses frequently. The reference software does it right generally, so you don't see so much reuse earlier in Bitcoin's history.
why cant they force to use that design in QT ?

An address is just a string of letters there is nothing you can do to prevent someone from using it more than once.  The client does try to discourage that but many people insist and some probably would use command line to dump the keys if that is what it took to ensure they can reuse the address.   
947  Economy / Economics / Re: Why controlling BTC supply is possible on: May 24, 2014, 02:25:36 PM
Control is probably the wrong word, influence is a better choice.  Still the purchasing power of a unit of currency is based on the effective money supply.  If FRB raises the effective money supply by 20% then the purchasing power of each currency unit is likewise reduced.  It doesn't matter if you hold "real BTC" or "fake BTC" the purchasing power is devalued.  This is no different than the fact that you can not use a bank and do all your transactions in cash (dollars) but it doesn't change the fact that inflation will affect prices.  It isn't like merchants value "cash" dollars more than "bank" dollars.

Quote
If you use online wallets, you get promises of bitcoins. Use your own wallet, however, and suddenly those are YOUR bitcoins, no questions asked.

This is true but it deals with counterparty risk. There is no counterparty risk if you hold the private key.  This is something I always recommend and the more people that hold their own private keys the less of an effect a FRB system would have on the money supply.  However we are all in this together.  If some users allow their coins (either for the promise of interest or through apathy/ignorance) to be used in a fractional reserve then it affects everyone.
948  Other / Beginners & Help / Re: bitcoin transfer fees? on: May 24, 2014, 02:20:53 PM
he default transaction fee is 0.0001 BTC
Well the default transaction fee is not 0.0001btc, its just an amount that is generally sufficient for making tx, but sometimes to prioritize your tx the blockchain.info sometimes automatically cuts 0.0002btc or more as a tx fee.

No the min fee to relay for low priority transactions is 100 bits (0.1 mBTC) per KB.  This is being reduced to 10 bits (0.01 mBTC) per KB.  Transactions can be larger than 1000 bytes.  Tx size is rounded up to the next KB for the purpose of computing the required fee.
949  Economy / Trading Discussion / Re: Is it safe to exchange BTC to Amazon Gift card on localbitcoins? on: May 24, 2014, 03:37:14 AM
Anything purchased with a credit card can be charged back because the chargeback is done via the credit card.   So if someone is offering xyz for BTC and you can purchased xyz with a credit card it really is no different than accepting a credit card.  Usually gift cards can also be reported stolen directly to the issuer as well, the funds frozen and the balance transferred to a new card.  In a dispute the issuer will want proof of purchase and the seller is the one who will have that. 
950  Bitcoin / Bitcoin Discussion / Re: [POLL] End the 'bit' controversy: What to (nick)name 100 Satoshi / 1 µXBT on: May 23, 2014, 09:22:06 PM
Feel free to sell your coins. I am more informed now than I was two years ago and hopefully will be more informed two years from now.  I also believed standardizing pricing mBTC was preferable but I now see that as a temporary measure which would probably need to be repeated again.  My opinions change based on new information and observations, most people call that learning.

wow, are you sure? Since if bitcoin becomes worth as much as $1,000,000 per coin than 1 satoshi would be worth exactly $0.01 and 1µBTC would be exactly $1

Do you really think we need to move even more decimal spaces? What do you think bitcoin will be worth then, a billion?

I have no idea how you got that from what I wrote and I suspect you don't either.
951  Alternate cryptocurrencies / Altcoin Discussion / Re: [PoS] Economic Clustering on: May 23, 2014, 08:57:02 PM
Quote
If a new user joins Nxt and there are several blockchains he should just ask friends, who brought him there, what blockchain to download (hash of a recent block is enough).

If this worked you wouldn't need mining/forging/minting you would just ask your trusted friends and know which tx are right.  So why are you using PoS to begin with if you can just ask your trusted authority which chain to use.  However what if you have two trusted friends and one says chain A is the "best" and one says chain B is the "best".  Or what if you friends are wrong, they all think "A" is the best chain but they are minority of users?   Or what if someone had no trusted friends (pretty dubious concept for a trustless network to need trusted oracles)?

Taken to the logical extreme you wouldn't ask just one or two or a dozen nodes you would connect to all of them (or as many as you possibly could) hundreds or thousands of nodes and poll them to find the best chain.   The problem with this is it is vulnerable to a sybil attack and preventing that in a decentralized pseudo anonymous network is an unsolved problem.  PoX systems acts as a PROXY for consensus bypassing the sybil attack by not attempting to restrict nodes and instead relying on the proxy (which should be harder to spoof than identity) rather than the opinion of individual nodes.  Of course we now have just made a full circle.  The very fact that a network is using PoX means that the opinion of nodes trusted or otherwise is insufficient to achieve a consensus.  If you could achieve consensus by checking with your friends then why are you using PoS to begin with.

Also when talking about attacks and vulnerabilities will simplify the scenario that the attacker makes a chain of double spends and the "good guys" make a chain of legit spends.  The reality is an attack can very easily include legitimate payments in the "attack" chain, and then add double spends of those in the "legit" chain.  So as a practical example say BTC-E and Bitstamp were both double spent however one was paid in chain A and double spent in chain B and the other was reversed.   How exactly are they going to decide on a consensus?  Which one is going to fall on the swords and potentially low millions of dollars by accepting the chain where they were double spent?

Note: this isn't an analysis of the "EC" as the key elements are still magical secret sauce to be revealed at a later date but your interpretation of how it would work doesn't.
952  Bitcoin / Bitcoin Discussion / Re: [POLL] End the 'bit' controversy: What to (nick)name 100 Satoshi / 1 µXBT on: May 23, 2014, 08:39:20 PM
Feel free to sell your coins.

I am seriously considering selling a portion. If popularity rather than correctness is what is important, then it would be silly not to invest in the Alt with the highest transaction volume.

Dogecoin does not have this problem because the unit in common usage (1 doge) is worth such a small amount of money (ignoring financial software integration concerns -- that would be an implementation detail: a correctness thing.)

Sounds like a super investing strategy.  Obviously the nominal units not the actual value being transacted is what matters.
953  Bitcoin / Bitcoin Discussion / Re: [POLL] End the 'bit' controversy: What to (nick)name 100 Satoshi / 1 µXBT on: May 23, 2014, 08:13:06 PM
Feel free to sell your coins. I am more informed now than I was two years ago and hopefully will be more informed two years from now.  I also believed standardizing pricing mBTC was preferable but I now see that as a temporary measure which would probably need to be repeated again.  My opinions change based on new information and observations, most people call that learning.
954  Bitcoin / Bitcoin Discussion / Re: [POLL] End the 'bit' controversy: What to (nick)name 100 Satoshi / 1 µXBT on: May 23, 2014, 05:31:42 PM
So since you felt the need to quote me from 2 years ago here is a new quote.

Millies, mBTC, mikes, uBTC have been proven to be horrible.  They are cludgy and nerdy and the chance of mainstream adoption is essentially zil.  Nothing has really happened after a couple years of pushing it. 

Bits is the only thing which has shown any momentum at all.  If BitPay starts using it, we will as well, hopefully others will and I have faith humans who can conceptualize a decentralized peer to peer currency system will be able to figure out bits.  "Bits" is a good colloquial for uBTC.  The idea that people won't be able to figure it out is just silly.  "That will be 22 bits please", short, simple, easy.  It still provides two decimal places which means easy integration into legacy accounting software.  We use uBTC internally for this exact reason.  Many accounting software packages can't handle the exchange rates or precision required to use either BTC or satoshis.  
955  Economy / Economics / Re: Why controlling BTC supply is possible on: May 23, 2014, 05:06:43 PM
Borrowing, lending, and credit doesn't require fractional reserve banking.  Now if you are a banker there is nothing better than lending someone elses money and keeping all (or almost all) the profits but it isn't a requirement.

If I have 1 BTC and I lend it to you that was done without fractional reserve banking.  If someday Bitpay floats a 20,000 BTC, 10 year bond @ 3.5% interest that would be another form of lending that doesn't involve fractional reserve banking.
956  Bitcoin / Bitcoin Discussion / Re: Double Spending for BTC businesses - Best practice Solutions BIP 70 ? on: May 23, 2014, 03:47:39 PM
I can't believe there is no service or software available to check duplicate(/multiple) transaction requests. Obviously, our system would then invalidate the transaction.

It is probably good there is no such service.  It would be rather trivial to make a service like that however double spend detection alone can't guarantee a tx won't be double spent (technically neither can confirmations).  Double spend detection can provide a reasonable assurance that your transaction has "won the race" (propagated the network) and ensure that no honest miner is working against you.  However a Finney attack can't be detected until after it has occurred by monitoring the network.  Likewise a thief could defraud you by working directly with a malicious pool.  There is no requirement that transactions have to be sent over the network (and no way to enforce that requirement if there was).  So a thief conspiring with a miner/pool doesn't have to broadcast the double spend, and this means there is nothing to detect.  Your first indication would be when the dishonest miner broadcasts a block with the double spend and your 0-confirm payment becomes invalid.

All of these factors depend heavily on what you are selling, how anonymous it is, how convertable it is to a thief, how much it is worth, etc.  There is no magic or simple "oh if you do this you will be safe".  It would not be difficult for a competent developer to code up a detection network but it should be part of a larger risk analysis.  Some services will simply always need confirmations or a way to secure alternate payment.  One example of this would be a grocery store.  Grocery store already accepts credit cards (and the associated risk).  If the store wanted to accept 0-confirm transactions for fast checkout line payment they could have users register a credit card and sign an agreement that if their bitcoin payment doesn't confirm the backup card will be charged.  The store is not taking any more risk.  If a thief has a stolen credit card and willingness to use it in person they would simply pay with the stolen credit card rather than try to perform a double spend.  So there are a lot of potential solutions but it will be very business specific.  What works for one business will not necessarily work for another.  Having a cookie cutter solution almost guarantees that naive businesses will be defrauded.
957  Bitcoin / Bitcoin Discussion / Re: Double Spending for BTC businesses - Best practice Solutions BIP 70 ? on: May 23, 2014, 03:18:21 PM
I see, thanks mate - wondering if Double Spending problem can be negated with 0 Confirmations?

No.  If it could then we wouldn't need confirmations, blocks, mining, and the massive expenditure of hardware and energy that goes along with it.   "Mining" is forcing a consensus on the network as to the ordering of transactions.  You "may" be able to accept 0-confirm txs with no or an acceptable rate of fraud but everything will depend on what you are selling, how much a theft is worth, if it is repeatable, how convertable would it be for a thief, how traceable, etc.

Nobody can say "in 100% of scenarios you must use X confirmations".  Well they can say it but they would be wrong.

To give you an example at one time Tangible Cryptography sold mobile phone reloads for Bitcoins.  For phone codes (which could be used to recharge any phone) we required 1 confirmation (sometimes 2 if we experienced a large amount of volume).  For direct reloads (where the user supplies a phone number and the time/value is directly added to their account) we didn't require any confirmations*.  Since the purchase was linked to a phone account the risk of a double spend was reduced and the repeatability of the attack was also reduced.  For BitSimple (a direct broker/dealer in Bitcoins) we require 3 confirmations as some of the withdraw methods as irreversible.

It all comes down to risk management.



*It is important to understand how you can detect double spends on the network using multiple nodes (listening nodes).  This doesn't guarantee a double spend (the thief could have a secret deal with one or more miners) but it does ensure you will not lose a "race" which ensures honest miners won't be working against you simply because they encountered the double spend first.  You should not accept 0-confirm transactions unless you understand the risks involved.  This means understanding how tx are relayed, what can prevent tx from being relayed, how an attacker could work directly with a miner, how a "Finney Attack" works and why it can't be detected. 
958  Bitcoin / Bitcoin Discussion / Re: Double Spending for BTC businesses - Best practice Solutions BIP 70 ? on: May 23, 2014, 03:04:50 PM
No BIP 70 doesn't solve the problem of double spending.  That is the point of confirmations.   How many confirmations you should wait for will depend on exactly what you are selling, what it is worth, how likely someone is to try and steal it.

Even 1 confirmation will require significant computing power at significant cost to reverse.  If that is sufficient for your service will depend on what the service is and how valuable a reversal would be.   Is 1-confirm sufficient for selling a digital game service which you can revoke later if needed? Yes and 0 confirms is probably good enough as well.   Is 1-confirm sufficient for a service that converts BTC to USD and instantly sends it to any bank in the world? No, not even close.
959  Other / Beginners & Help / Re: bitcoin transfer fees? on: May 23, 2014, 02:55:22 PM
First of all I'm no computer wizz so maybe its something I'm doing wrong but I always read articles that say it only costs a tiny percentage to send bitcoins, today I sent $0.05 from my blockchain wallet to a different wallet I have just as a test and it cost me $0.11 in fees, WTF, and I thought banks were ripping me off.


read up on http://bitcoinfees.com/

the default transaction fee is 0.0001 BTC (0.1 mBTC) so that's about 5 cents. if there are a lot of small inputs from many addresses, the size of the transaction will be larger, thus requiring a higher fee than usual.

yes this is a problem with bitcoin, it becomes difficult to send microtransactions.



The min fee to relay (there is no such thing as default fee) is 0.01 mBTC in v0.9 (that is 0.5 cents) for LOW PRIORITY TXS.  The min fee to relay high priority txs is zero.   The size of the transaction is what matters.   The OP most likely has a bunch of worthless dust spam he got from "free bitcoin" sites.
960  Alternate cryptocurrencies / Altcoin Discussion / Re: Founder of Ripple is announcing he is dumping his XRP. Ripple crashes 35% and st on: May 23, 2014, 08:55:14 AM
I wouldn't say the worst is over.   Jed owns more XRP than the entire global float.   While you could make a comparison to Satoshi it would be like Satoshi dumping 15M "bonus" BTC on the market.   How low the price goes really depends on how it is sold off.  If dumped as a 9B XRP market order it could crush the price 99% from here.   On the other hand one way to "sell" it would be a massive 9B limit order just above the current market price.   While the price wouldn't go down (at least not directly) it certainly wouldn't be going up for a long time.
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