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Bitcoin Android Released (github.com/barmstrong)
82 points by barmstrong on July 6, 2011 | hide | past | favorite | 32 comments


While I can't speak to the legal or political implications of the product or supporting infrastructure, I'm thrilled with the idea of a mobile application that provides for the exchange of "currency" in an autonomous manner.

The exchange of value outside of the established models (Gov't issued currency / PayPal / Google Checkout / next iteration thereof) has the potential to provide a huge opportunity for those of us involved in the space of online media and web applications.

Mobile implementations to bring the utility of the Bitcoin project into the palm of the hand bridge an intimidating virtual-to-real gap for many potential users.

In my opinion, the development of this mobile application, as well as similar projects, is a first step towards the more widespread adoption of the Bitcoin currency, in whatever (hopefully at least semi-legal, and legitimate) form it may finally take.

I'll observe with great interest.


I like the server-client model more, for example BitPay which uses instawallet.org (http://forum.bitcoin.org/index.php?topic=24452.0).

There is also mtgox vouchers-app: http://forum.bitcoin.org/index.php?topic=25307.0

These apps use QR codes, but I think the way to go is NFC communication.

The benefit is instant transactions with server-client model, but on the downside you have to rely on 3rd party. I think it isn't that big downside, since you have always handed your money to 3rd party before bitcoin...


We went with QR codes for initial development because most phones still don't have NFC built in yet. I definitely agree, though. In the long term, NFC will take over. It's on the dock for future versions.

It's still early to push any cloud wallet solution for the mass market. Until any of these services build up trusted reputations, handling the transactions on the phone is the best way to go for the average user. Setting up personal servers works for nerds like us, but isn't a general enough solution.


The entire production blockchain is 14MB right now. We keep this on the SD card of the phone. Many smartphones today have 8GB SD cards or more, so 14MB is not a big deal.

I agree though, I think a thin-client or server-client model would be better long run. There just isn't a service I'd trust with it currently.


Where are you getting the 14MB figure? I see a blk00001.dat file on my PC which is already more than 300MB.

The latest compressed blockchain download available here at the time of writing is 280MB: http://bitcoin.bluematt.me/bitcoin-nightly/blockchain-nightl...

It is known that even PCs won't be able to handle the full blockchain eventually, let alone smartphones. Supernodes will be needed if bitcoin becomes popular. https://en.bitcoin.it/wiki/Scalability

edit: I see now that there is indeed a 14MB blockchain file in the source: https://github.com/barmstrong/bitcoin-android/blob/master/as.... I suppose this is not the full blockchain, but just the block headers. This is described as "Simplified Payment Verification" in Satoshi's paper.


It could very well be just block headers, to be honest I'm not sure (didn't realize the desktop version was that big). We're using the bitcoinj library and contributing back some patches along the way. Mike Hearn at Google wrote the blockstorage and deserves a ton of credit for it: http://code.google.com/p/bitcoinj/


"BitCoinJ implements the "simplified payment verification" mode of Satoshis paper. It does not store a full copy of the block chain, rather, it stores what it needs in order to verify transactions with the aid of an untrusted peer node."

one click * HN user base = global time saving :)


Am I the only one interested in mobile payment apps that let you buy real things with dollars? Are dollars suddenly that uncool?


Your comment is a bit like commenting "am I the only one who only likes Android?" on every Apple story. In other words, it does not seem to convey any useful information related to BitCoin.


Well, those will come maybe in couple of years I guess. Banks/Payment processors etc. are generally very slow to innovate on new technology, so I think we won't see dollar-based payment-app very soon.

I think the biggest reason why bitcoin is so fast to innovate is that there is no barrier to entry, which means that anyone can create bitcoin android client. But if you want to create dollar-based android payment software, you have to be either visa or mastercard, or some big bank.


Several already exist.

There are barriers to entry, such as laws; Bitcoin simply ignores them. Without real merchants, Bitcoin is useless to me no matter how fast it innovates. And even if it were useful, it's still [going to be] illegal.


This is much larger than the US only. Even when USD-nominated mobile payment would finally be introduced in the US, it will be a long time before it is accepted in other countries, especially emerging economies.

Also, merchants don't have to jump through any of the bank's hoops to accept Bitcoin.

A grassroots initiative like this can allow for global, low-cost, payments from your mobile phone, without needing to wait for slow banking innovation.

Right, it is still not a given that it will succeed, but it's much to early to dismiss it...


It's distributed so it's probably hard to kill. Unless your the NSA or CIA and have tons of computing power with which you can just flood the market with rendering everyone else's bitcoins useless...

Seriously though, it seems like Bitcoin is really vulnerable to this sort of attack, no matter what "hardening" features are builtin to make mining harder. NSA can spend a week and kill it all off. Is there a way to block whole hash blocks that the NSA or someone else who might have a large chunk of the bitcoin market?

Still I wouldn't write it off so quick, it's the branding/legitimacy question along with traction among merchants and usd<->bitcoin that's holding it back right now.


You're right, it's pretty theoretical at this point. But as Chris Dixon points out, most big ideas start out looking like toys: http://cdixon.org/2010/01/03/the-next-big-thing-will-start-o...


Don't be ridiculous. The USD isn't about to be disintermediated. The Euro, maybe...but then by the USD.


Bitcoin is unlikely to replace the dollar, but if I were Paypal I'd be worried..


I don't know why this got downvoted.

With the financial trouble in Portugal, Spain and Greece and the imbalance in monetary and fiscal health (Contrast those 3 with Germany) within the EU, the Euro looks very shaky indeed.


Thanks for that link... amazing how well bitcoin fits into that picture.


The dollar is so 2000's


Oh good, just what I needed. Less battery life on my phone.


I think this app is less about mining and more about payments on the go.


Word. I imagine it would take my old HTC Magic about 9 years to process the block chain. Also even though I wouldn't keep much BTC in this wallet, I don't like the idea of just storing it 'in the cloud' or whatever.


We actually prepackage a recent blockchain with the app when you download it. So it only needs to udpate the last bit the first time you run it (< 1 minute over wifi). After that future updates are near instant (a few seconds) over 3G or WiFi.


Brilliant software... have been waiting for this.

One obvious question: is there anything to prevent someone from repackaging this, as it's open source, and modifying it to rob folks?


No. Just like any other open source software. It's also possible that people who download the apk from the Android Market Place are getting a backdoored version of the software.

This relies on trust.

Does anyone remember Paypal updating their iPhone app last year to do SSL certificate verification because up until that point it was trivially MITM'able?


Thanks for explaining all of this in the comments. I was wondering all of these things...


"Wallet file backed up in the cloud (synced to your Google account) in case you lose your phone." Here's hoping that the wallet is encrypted.


We make no guarantees about the security of the backup. This is beta software :)


Can you tell us where exactly the wallet.dat file and the block chain are stored on the android? I sent 0.01BTC to my phone a while ago, and it has yet to show up (so I'd like to grab the wallet.dat for backup), and it's showing a swirling circle at the top, meaning it's still downloading, and I'd like to check if it's actually doing anything (file size increasing?)


Can anyone speak to how this app works? Does the phone store a local copy of the block chain?



crashed for me =(




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