Newbie All-Day - Ask All Your Bitcoin Questions Here! - page 3.

btchris

hero member

Activity: 672

Merit: 504

a.k.a. gurnec on GitHub

Quote from: Loophole on October 12, 2014, 05:43:25 AM

Quote from: 888coin on October 12, 2014, 05:24:26 AM

Any step-by-step guide how to double spend bitcoin?

I know I can't do this with my little hashpower but I'm just interested in understanding the theory behind this.

Thanks.

You don't really need any hashing power to attempt double spending. You just need to create two different transactions that both spend a particular tx output, and you broadcast both the two transactions to the network. Eventually one will get confirmed, and one will never get confirmed.

But if you are talking about reverting a confirmed transaction and replacing it with another one, it will be a different story.

There exist tools (such as the one here, although it's not intended for newbies: https://github.com/petertodd/replace-by-fee-tools) that will create double-spend transactions which may work some of the time. By "work", I only mean that it can "fool" recipients who choose not to wait for confirmations.

(FYI many people don't consider the term "double-spend" to ever apply to 0-conf transactions...)

Loophole

hero member

Activity: 619

Merit: 500

Quote from: 888coin on October 12, 2014, 05:24:26 AM

Any step-by-step guide how to double spend bitcoin?

I know I can't do this with my little hashpower but I'm just interested in understanding the theory behind this.

Thanks.

You don't really need any hashing power to attempt double spending. You just need to create two different transactions that both spend a particular tx output, and you broadcast both the two transactions to the network. Eventually one will get confirmed, and one will never get confirmed.

But if you are talking about reverting a confirmed transaction and replacing it with another one, it will be a different story.

888coin

member

Activity: 63

Merit: 10

Any step-by-step guide how to double spend bitcoin?

I know I can't do this with my little hashpower but I'm just interested in understanding the theory behind this.

Thanks.

LiteCoinGuy

legendary

Activity: 1148

Merit: 1014

In Satoshi I Trust

Where is satoshi now?

marcotheminer

legendary

Activity: 2072

Merit: 1049

┴puoʎǝq ʞool┴

Ask all your questions!

Hellcat

newbie

Activity: 44

Merit: 0

Quote from: shorena on September 18, 2014, 12:16:58 PM

Quote from: marcotheminer on September 18, 2014, 11:44:23 AM

Quote from: Hellcat on September 16, 2014, 09:49:56 AM

Does the stratum proxy work ok on a 3g connection? I need to move my equipment and the new place doesn't have any wired internet.

Im not sure. Can anyone help out?

Nope sorry. It probably dependa on the hashingpower behind the proxy anyway. This might be interesting though.

https://github.com/pooler/rollproxy

A proxy to reduce getwork requests and thus bandwidth usage.

Thanks. Will try to get it working

DannyHamilton

legendary

Activity: 3472

Merit: 4801

Quote from: BillyBobZorton on September 24, 2014, 09:10:31 AM

On a scale of 1 to 10, what are the chances Bitcoin goes to 10, and what are the chances Bitcoin goes to 10K?

50/50

BillyBobZorton

legendary

Activity: 1204

Merit: 1028

On a scale of 1 to 10, what are the chances Bitcoin goes to 10, and what are the chances Bitcoin goes to 10K?

Bernard Lerring

sr. member

Activity: 294

Merit: 250

An update on the Dymo LetraTag:

Bought one after reading a lot of good reviews on Amazon. Bought it from a high street shop.

Put brand new Duracell (4 x AA Ultra Plus, or something) in and every time I went to make a print the "battery low" warning would come on. I perservered and printed out my keys, even trying some other brand new Duracell AA standard batteries and still the "battery low" warning.

I wasn't happy with this and took it back for an exchange, thinking that the unit I had was dodgy. The replacement did exactly the same.

So, I've given up on the LetraTag, got my money back, and will stick to hand writing BTC keys in future. I considered a Brother P-Touch model but they are too expensive and the cartridges are also pricey.

Farmer17

hero member

Activity: 674

Merit: 500

Very true. With the BIP38 encryption (available on bitaddress), even if someone pick up your paper wallet, your bitcoin is still safe as long as they have no knowledge of your password.

btchris

hero member

Activity: 672

Merit: 504

a.k.a. gurnec on GitHub

Quote from: shorena on September 20, 2014, 09:53:23 AM

If you worry about the printers cache, AFAIK this is usually only a problem with the big office machines that have actual harddrives in them. Most home use printers have no long term storrage.

True, but most printers run close-source software that do things many don't know about and may not want, even home printers. For example it's known that many (most?) printers will refuse to print counterfeit money using various technologies[1], and some printers surreptitiously include nearly-invisible identifiers to link the printed document to the individual printer which printed it[2]. If they can do this, who knows what could be next (I know this does sound a bit tin-foil-hattish...)

Printers can also be theoretically infected by malware remotely, although I don't think there are any documented cases of this outside a research setting[3] (not yet, anyways).

Some paper wallets / BIP32 backups (e.g. Armory) allow you to encrypt before printing. If you write down the encryption password on the printout, you'll have everything you need to restore the wallet in one place, and you'll remain safe from such printers.

[1] http://en.wikipedia.org/wiki/EURion_constellation
[2] https://www.eff.org/issues/printers
[3] http://www.bbc.com/news/technology-29203776

Farmer17

hero member

Activity: 674

Merit: 500

Quote from: eenaccountant on September 20, 2014, 06:18:18 AM

What's the best thing to start as a beginner? I was planning to buy 0.1/2/3 BTC. I'm not mining by the way.

The best thing to start to understand bitcoin, is to read the bitcoin wiki (https://bitcoin.it/), the Coindesk guide (http://www.coindesk.com/information/) and the whitepaper (https://bitcoin.org/bitcoin.pdf).

The best thing to start to invest in bitcoin, is to buy it directly with fiat money.

The best thing to start to earn some bitcoin, is to sell your products or services with bitcoin.

shorena

copper member

Activity: 1498

Merit: 1528

No I dont escrow anymore.

Quote from: Bernard Lerring on September 20, 2014, 09:58:54 AM

I bought a LetraTag yesterday for this very purpose. I guess I'll check on the print every year to see if it's starting to fade and reprint if it is.

Better than my handwriting, anyway.

I think it greatly depends on what you print on. I dont know why, but when I saw that machine I had these supermarket printers in mind. They print on very thin thermopaper and some even have a warning on the back. The warning reads: no sunlight, no chemicals, no oil, no fats, no pressure, no heat, nothing that contains softeners (so maybe my wraps are a bad idea). You basically cant even touch them. Anyway now that I looked at the machine again I think its printing on thick plastic. Dont some of them even "engrave" the print? That should work for ~10 years Wink

Bernard Lerring

sr. member

Activity: 294

Merit: 250

I bought a LetraTag yesterday for this very purpose. I guess I'll check on the print every year to see if it's starting to fade and reprint if it is.

Better than my handwriting, anyway.

shorena

copper member

Activity: 1498

Merit: 1528

No I dont escrow anymore.

Quote from: eenaccountant on September 20, 2014, 06:18:18 AM

What's the best thing to start as a beginner? I was planning to buy 0.1/2/3 BTC. I'm not mining by the way.

Reading the whitepaper [1] was the best I did in the beginning. Also reading it after 3 and 6 months did help to understand bitcoin better. Don expect to understand it fully while reading first just take in as much as you can.

Quote from: ?? on ??

I don't understand what is bitcoin, how can i invest?where can i get bitcoin?I want to understand hope you can help me.

Bitcoin is a forum of currency, but no bank or state is behind it. Investing in bitcoin is as simple as buying bitcoin when the price is low. E.g. today Wink

Well yesterday was better, but that easy to say in hindsight. How to buy. Well you could register with one of the exchanges like kraken or bitstamp, transfer money to their bank account and buy bitcoin. Or you could meet with someone in person using local bitcoins. You could also try the currency exchange section here. If you just want to learn how to use it, just buy a little to play around with. Idk like a pizza worth Wink

Quote from: Bernard Lerring on September 20, 2014, 09:41:08 AM

Is a Dymo LetraTag a good idea for printing out private cold storage keys and then sticking them into an envelope? Once the batteries are removed the printer memory is wiped, right?

I've asked this question before but no-one answered.

Do you think the thermal print will fade within, say 10 years, if enclosed in an envelope and away from heat/light?

Dont use thermal print for something that has to last long. I have old (3 years old) receipts that I can no longer read. I kept them in a Leitz folder in saran wrap (*) and they are usualy in the dark. If you worry about the printers cache, AFAIK this is usually only a problem with the big office machines that have actual harddrives in them. Most home use printers have no long term storrage.

[1] https://bitcoin.org/bitcoin.pdf
(*) not sure if thats the correct translation, these:

Bernard Lerring

sr. member

Activity: 294

Merit: 250

Is a Dymo LetraTag a good idea for printing out private cold storage keys and then sticking them into an envelope? Once the batteries are removed the printer memory is wiped, right?

I've asked this question before but no-one answered.

Do you think the thermal print will fade within, say 10 years, if enclosed in an envelope and away from heat/light?

eenaccountant

newbie

Activity: 1

Merit: 0

What's the best thing to start as a beginner? I was planning to buy 0.1/2/3 BTC. I'm not mining by the way.

shorena

copper member

Activity: 1498

Merit: 1528

No I dont escrow anymore.

Quote from: marcotheminer on September 18, 2014, 11:44:23 AM

Quote from: Hellcat on September 16, 2014, 09:49:56 AM

Does the stratum proxy work ok on a 3g connection? I need to move my equipment and the new place doesn't have any wired internet.

Im not sure. Can anyone help out?

Nope sorry. It probably dependa on the hashingpower behind the proxy anyway. This might be interesting though.

https://github.com/pooler/rollproxy

A proxy to reduce getwork requests and thus bandwidth usage.

shorena

copper member

Activity: 1498

Merit: 1528

No I dont escrow anymore.

Quote from: BigBenny on September 18, 2014, 12:04:55 PM

How much bitcoin do you think i need to start mining?

I made a calculation earlier about how profitable cloudmining is. The same can be said for buying hardware with the additional problem that the hardware has to be shipped, set up and might be faulty (from time to time). If you just want to mine as a hobby and not to earn money you could buy some cheap 1st or 2nd gen ASICs or mine alts with your GPU/CPU.

BigBenny

newbie

Activity: 28

Merit: 0

How much bitcoin do you think i need to start mining?

Topic: Newbie All-Day - Ask All Your Bitcoin Questions Here! - page 3. (Read 7618 times)