Why do you have to download the whole history since genesis?

[terabit]

It takes hours to download the whole history! And as it gets closer to finished it starts taking longer.. why does it have to do the whole thing?

[hamdi]

to control all balances

[imsaguy]

It takes hours to download the whole history! And as it gets closer to finished it starts taking longer.. why does it have to do the whole thing?

Every block includes the previous block as a reference so your computer has to verify all the way back that everything is in order.  The reason that the later blocks/history take longer is that there are more transactions now than there were a year ago.

[drakahn]

It takes hours to download the whole history! And as it gets closer to finished it starts taking longer.. why does it have to do the whole thing?

There are thin clients and online wallets for now if the blockchain is too heavy.

[Gabi]

Because Bitcoin rely on ppl having the client with the full blockchain with all the transactions

[Stephen Gornick]

It takes hours to download the whole history! And as it gets closer to finished it starts taking longer.. why does it have to do the whole thing?

To verify that transactions have not been previously spent, Bitcoin uses a chain of data blocks.  This is called the blockchain.



 - http://en.bitcoin.it/wiki/Blockchain

So to verify a transaction, there needs to be a chain with integrity, all the way back to block #0.

The reason it starts to take longer with more recent blocks has to do with Bitcoin's growth as a payment network.  In the past few months, half or more of those transactions are wagers from a single online gambling service,  SatoshiDICE, incidentally

If you are finding this to be too slow, make sure you are using the most recent release of the software (v0.6.3) as that has performance improvements.  Also, if you are running on an encrypted filesystem, that will really bog things down.  At some point in the future, the Bitcoin.org client will be getting a couple of improvements -- LevelDB (instead of BDB) for storage and Ultraprune, which will help make it so less storage will be necessary.

Not all users need to run the full bitcoin.org client.  Some would be just fine running Simplified Payment Verification (SPV) clients.  Electrum is an example of a thin client that uses a server for transactions yet remains secure where the private key(s) are stored locally.  There is no blockchain download required.

[Glacio]

Judging by the average weight of a single one of these days datablocks, I'm pretty sure that the "thin" wallets are the future of the Bitcoin economy.
Clearly I'm not saying the classic type wallets will totally disappear...

[stoneyjonez]

If you don't want to have to download the blockchain all the time (or at all), check out Electrum. I first tried it about a week ago and haven't used another wallet since!

[JompinDox]

If you don't want to have to download the blockchain all the time (or at all), check out Electrum. I first tried it about a week ago and haven't used another wallet since!

Are you using it on Windows or Linux?
I'm trying to get it installed on Slacko 5.3.3 but am having trouble with the dependencies.

[stoneyjonez]

Are you using it on Windows or Linux?
I'm trying to get it installed on Slacko 5.3.3 but am having trouble with the dependencies.

So far, I've used it on Windows and Mac. The Windows one is far better than its Mac counterpart. If you can't get it working, try to run the Windows version in Wine.

[deus-ex-machina]

Downloading it now. Thanks in advance for removing the only bad part of Bitcoin.

No, that wasn't sarcasm.

[JompinDox]

Are you using it on Windows or Linux?
I'm trying to get it installed on Slacko 5.3.3 but am having trouble with the dependencies.

So far, I've used it on Windows and Mac. The Windows one is far better than its Mac counterpart. If you can't get it working, try to run the Windows version in Wine.

Why? I thought they had the same codebase?

[kaii]

Here is a relevant article on the Bitcoin wiki about clients that don't download the entire blockchain (i.e. thin clients).

https://en.bitcoin.it/wiki/Thin_Client_Security

There are added security risks because there is no way for a thin client to verify a transaction independently of contacting other nodes or servers. This makes thin clients susceptible to a greater variety of attacks, especially on untrusted networks.

[Gabi]

Downloading it now. Thanks in advance for removing the only bad part of Bitcoin.

No, that wasn't sarcasm.

Please note that having people running the full client with the full blockchain help making bitcoin safe.

[muyuu]

In all fairness not all the blockchain is necessary to operate, just the latest N blocks would suffice (for N no smaller than 10). But that's the way the "official" client works right now.

Needless to say, this will need changing sometime soon. Especially after satoshidice started crapping the blockchain.

On the bright side, you have locally in your computer all balances and all transactions in bitcoin ever. That's cool if you know how to use it.

[chaosman]

Just out of curiosity, if you haven't logged on your BTC client 3 months in and received a payment a week after you stopped using the client.
Wouldn't it be possible that if we didnt download the full blockchain the client's wallet wouldnt be updated properly?

[muyuu]

Just out of curiosity, if you haven't logged on your BTC client 3 months in and received a payment a week after you stopped using the client.
Wouldn't it be possible that if we didnt download the full blockchain the client's wallet wouldnt be updated properly?

Sure. The wallet will be updated when it reaches that part of the blockchain. However that doesn't change that your balance is there, even if your wallet doesn't reflect it. You just need to give it time. You would still be able to check your balance with blockexplorer.com , for instance.

[kaii]

Just out of curiosity, if you haven't logged on your BTC client 3 months in and received a payment a week after you stopped using the client.
Wouldn't it be possible that if we didnt download the full blockchain the client's wallet wouldnt be updated properly?

To calculate wallet balances, the client just needs to know of any transactions where one of its addresses is an in/out of a transaction. In a client that downloads the entire blockchain, the balance is updated when the blockchain update reaches a relevant transaction. If the client relies on a server (like Electrum) then it would be easy for the server to send the right data when you open the wallet.

[chaosman]

Just out of curiosity, if you haven't logged on your BTC client 3 months in and received a payment a week after you stopped using the client.
Wouldn't it be possible that if we didnt download the full blockchain the client's wallet wouldnt be updated properly?

Sure. The wallet will be updated when it reaches that part of the blockchain. However that doesn't change that your balance is there, even if your wallet doesn't reflect it. You just need to give it time. You would still be able to check your balance with blockexplorer.com , for instance.

I think I mistook your post. I thought you meant that if the client were to download the latest N blocks, and lets say where N == 200. That the wallet.dat would update even if the transaction was 1000 blocks back. I know that the wallet balance should be a certain amount -- if you look at block explorer -- but if the client were never to download that part of the blockchain how would they be able to spend it?

[chaosman]

Just out of curiosity, if you haven't logged on your BTC client 3 months in and received a payment a week after you stopped using the client.
Wouldn't it be possible that if we didnt download the full blockchain the client's wallet wouldnt be updated properly?

To calculate wallet balances, the client just needs to know of any transactions where one of its addresses is an in/out of a transaction. In a client that downloads the entire blockchain, the balance is updated when the blockchain update reaches a relevant transaction. If the client relies on a server (like Electrum) then it would be easy for the server to send the right data when you open the wallet.

Ohh alright that makes a lot of sense now. I would assume the server downloads the blockchain and notifies the client of the transaction etc?