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Bitcoins the hard way: Using the raw Bitcoin protocol

229 points by kens 13y ago

bluesign 13y ago
One of the best articles I've ever read about bitcoin.
- kidgorgeous 13y ago
  Came in here just to say that. Thank you for whoever posted this and more importantly, whoever wrote it.
  - timmclean 13y ago
    It looks like they're one and the same, so the karma is going to the right place :)
- kzahel 13y ago
  Agreed, this is a great reference and high level low level overview. Having though of doing the exact same thing, it's nice to have a guide in case I ever decide to do so. Thanks!
wmf 13y ago
Be careful if you try this at home; a lot of people have lost money this way. (Not sending change is a common mistake.)
- M4v3R 13y ago
  To elaborate on that. If not very careful, you can end up sending a big fee, since the fee is calculated in the following way: sum of all inputs values - sum of all outputs values "Change" is an output that you control to which you will send the remaining amount. Failing to do so will end up sending all remaining value as transaction fee, which then goes to the miners. If you end up doing that (as I did few months ago) you still have a chance though - through blockchain.info you can get information about who mined the block in which your transaction was included. If you're lucky, it will be one of the big pools. You can then try to contact them and ask to send the amount back to the originating address. In my case BTC Guild was nice enough to do exactly this.
  - yetfeo 13y ago
    With pools moving towards paying miners the transaction fees it becomes more difficult to recover from mistakes like this. The pool would have to contact the miners that received the fees to recover them.
- nkuttler 13y ago
  Don't do anything experimental with real coins. That's what testnet is for: https://en.bitcoin.it/wiki/Testnet https://en.bitcoin.it/wiki/Testnet. If you need a coin or two to get started, I run a testnet faucet at http://kuttler.eu/bitcoin/faucet/ http://kuttler.eu/bitcoin/faucet/. Or check out https://github.com/freewil/bitcoin-testnet-box https://github.com/freewil/bitcoin-testnet-box.
- implr 13y ago
  There was a patch[1] some time ago that prevents sending fees larger than 1 BTC. Still a lot of money, but it won't let you lose thousands of dollars. 1: https://github.com/bitcoin/bitcoin/pull/2949 https://github.com/bitcoin/bitcoin/pull/2949
aaron-lebo 13y ago
If you want something in a similar vein, Khan Academy has some good videos describing the protocol and not just a high-level overview (though there is that, too). https://www.khanacademy.org/economics-finance-domain/core-finance/money-and-banking/bitcoin/v/bitcoin-overview https://www.khanacademy.org/economics-finance-domain/core-fi...
gwillen 13y ago
Do not, do not, DO NOT, try writing raw transactions at home. You will fail and you will lose a lot of money. If you must: - Use testnet! If you don't know what testnet is, you have no business writing live raw transactions. - ALWAYS validate your transaction first by having bitcoind pretty-print it, and checking the output carefully, before sending.
- timmclean 13y ago
  > Do not, do not, DO NOT, try writing raw transactions at home. You will fail and you will lose a lot of money. I don't see the harm in putting a dollar or two into a new wallet just to have some fun. Just be careful not to mix up the private key with your real wallet, if you have one.
  - throwaway894597 13y ago
    > I don't see the harm in putting a dollar or two into a new wallet just to have some fun I did this with "a dollar or two" in early 2011 before USD parity. You might eventually be happier if you use "a satoshi or two" instead.
- csomar 13y ago
  If I remember correctly there is a testing network for bitcoin. You shouldn't try on real money but you should definitively try.
  - nkuttler 13y ago
    Right, it's called testnet. I left more info in another comment.
- implr 13y ago
  Unfortunately, there is no way to spend a multisig (or any other nonstandard) transaction besides using the createrawtransaction API. It would be really nice if somebody implemented a better(safer) interface for them - n-of-m transactions could seriously increase security in many scenarios, but it's hard to get them right.
ck2 13y ago
I've always wanted to learn how to query a coin network for things like current difficulty and total hashrate without running a full blown wallet to get a console. Is this documented anywhere perhaps? I cannot seem to find. This helps a little https://en.bitcoin.it/wiki/Protocol_specification https://en.bitcoin.it/wiki/Protocol_specification but very low level and no mention of hashrate
- kens 13y ago
  Try https://blockchain.info/stats https://blockchain.info/stats for stats from the past 24 hours. That site also has a whole lot of historical charts.
35524532525 13y ago
Linking to a thread about a paranoid blog/rant, regarding: "Bitcoin is a cryptographic botnet" Bitcoin, I believe after reviewing the protocol description here is a US gov’t black op. https://news.ycombinator.com/item?id=7165893 https://news.ycombinator.com/item?id=7165893 Possibly worth discussing, since it's reactionary slant was directly provoked by OP's topic. Seems to have gotten buried. Possible deliberate forum sliding? http://lunaticoutpost.com/Topic-Technique-1-FORUM-SLIDING http://lunaticoutpost.com/Topic-Technique-1-FORUM-SLIDING The only reason I might suggest considering this botnet premise is due to hardware mining. ASICs are pretty much the norm for mining now, and near as I can tell, there hasn't been much discussion regarding all the custom hardware floating around lately.
- deleted 13y ago
  [deleted]
- wmf 13y ago
  Not familiar with the crackpot index, huh? BTW, the behavior of ASICs is well understood and has been audited by the authors of mining software (who are independent from the ASIC vendors).

229 points by kens 13y ago

bluesign 13y ago

One of the best articles I've ever read about bitcoin.

kidgorgeous 13y ago
Came in here just to say that. Thank you for whoever posted this and more importantly, whoever wrote it.
- timmclean 13y ago
  It looks like they're one and the same, so the karma is going to the right place :)
kzahel 13y ago
Agreed, this is a great reference and high level low level overview. Having though of doing the exact same thing, it's nice to have a guide in case I ever decide to do so. Thanks!

wmf 13y ago

Be careful if you try this at home; a lot of people have lost money this way. (Not sending change is a common mistake.)

M4v3R 13y ago
To elaborate on that. If not very careful, you can end up sending a big fee, since the fee is calculated in the following way: sum of all inputs values - sum of all outputs values "Change" is an output that you control to which you will send the remaining amount. Failing to do so will end up sending all remaining value as transaction fee, which then goes to the miners. If you end up doing that (as I did few months ago) you still have a chance though - through blockchain.info you can get information about who mined the block in which your transaction was included. If you're lucky, it will be one of the big pools. You can then try to contact them and ask to send the amount back to the originating address. In my case BTC Guild was nice enough to do exactly this.
- yetfeo 13y ago
  With pools moving towards paying miners the transaction fees it becomes more difficult to recover from mistakes like this. The pool would have to contact the miners that received the fees to recover them.
nkuttler 13y ago
Don't do anything experimental with real coins. That's what testnet is for: https://en.bitcoin.it/wiki/Testnet https://en.bitcoin.it/wiki/Testnet. If you need a coin or two to get started, I run a testnet faucet at http://kuttler.eu/bitcoin/faucet/ http://kuttler.eu/bitcoin/faucet/. Or check out https://github.com/freewil/bitcoin-testnet-box https://github.com/freewil/bitcoin-testnet-box.
implr 13y ago
There was a patch[1] some time ago that prevents sending fees larger than 1 BTC. Still a lot of money, but it won't let you lose thousands of dollars. 1: https://github.com/bitcoin/bitcoin/pull/2949 https://github.com/bitcoin/bitcoin/pull/2949

aaron-lebo 13y ago

If you want something in a similar vein, Khan Academy has some good videos describing the protocol and not just a high-level overview (though there is that, too). https://www.khanacademy.org/economics-finance-domain/core-finance/money-and-banking/bitcoin/v/bitcoin-overview https://www.khanacademy.org/economics-finance-domain/core-fi...

gwillen 13y ago

Do not, do not, DO NOT, try writing raw transactions at home. You will fail and you will lose a lot of money. If you must: - Use testnet! If you don't know what testnet is, you have no business writing live raw transactions. - ALWAYS validate your transaction first by having bitcoind pretty-print it, and checking the output carefully, before sending.

timmclean 13y ago
> Do not, do not, DO NOT, try writing raw transactions at home. You will fail and you will lose a lot of money. I don't see the harm in putting a dollar or two into a new wallet just to have some fun. Just be careful not to mix up the private key with your real wallet, if you have one.
- throwaway894597 13y ago
  > I don't see the harm in putting a dollar or two into a new wallet just to have some fun I did this with "a dollar or two" in early 2011 before USD parity. You might eventually be happier if you use "a satoshi or two" instead.
csomar 13y ago
If I remember correctly there is a testing network for bitcoin. You shouldn't try on real money but you should definitively try.
- nkuttler 13y ago
  Right, it's called testnet. I left more info in another comment.
implr 13y ago
Unfortunately, there is no way to spend a multisig (or any other nonstandard) transaction besides using the createrawtransaction API. It would be really nice if somebody implemented a better(safer) interface for them - n-of-m transactions could seriously increase security in many scenarios, but it's hard to get them right.

ck2 13y ago

I've always wanted to learn how to query a coin network for things like current difficulty and total hashrate without running a full blown wallet to get a console. Is this documented anywhere perhaps? I cannot seem to find. This helps a little https://en.bitcoin.it/wiki/Protocol_specification https://en.bitcoin.it/wiki/Protocol_specification but very low level and no mention of hashrate

kens 13y ago
Try https://blockchain.info/stats https://blockchain.info/stats for stats from the past 24 hours. That site also has a whole lot of historical charts.

35524532525 13y ago

Linking to a thread about a paranoid blog/rant, regarding: "Bitcoin is a cryptographic botnet" Bitcoin, I believe after reviewing the protocol description here is a US gov’t black op. https://news.ycombinator.com/item?id=7165893 https://news.ycombinator.com/item?id=7165893 Possibly worth discussing, since it's reactionary slant was directly provoked by OP's topic. Seems to have gotten buried. Possible deliberate forum sliding? http://lunaticoutpost.com/Topic-Technique-1-FORUM-SLIDING http://lunaticoutpost.com/Topic-Technique-1-FORUM-SLIDING The only reason I might suggest considering this botnet premise is due to hardware mining. ASICs are pretty much the norm for mining now, and near as I can tell, there hasn't been much discussion regarding all the custom hardware floating around lately.

deleted 13y ago
[deleted]
wmf 13y ago
Not familiar with the crackpot index, huh? BTW, the behavior of ASICs is well understood and has been audited by the authors of mining software (who are independent from the ASIC vendors).