Bitcoin Forum

WARNING: If you are using Litecoin Wallet (on Android), be aware that a security vulnerability found in it may require that you send funds out from the wallet and reinstall it for it to be fixed. Unfortunately, there is still an issue with fee calculation in the client and it should only be used with caution.

This bounty was satisfied and awarded as of April 2nd, 2013.

Hello,

It's time to start a bounty for the first Litecoin wallet to be in the Google Play store for Android. The requirements are as follows:

1. Be able to send and receive Litecoins without requiring storage of a full copy of the blockchain on the device.
2. Litecoin private keys should either be stored on the mobile device or an encrypted copy of them be downloaded and only decrypted on the device (like blockchain.info's client and web app).
3. Provide a means to backup the private keys via QR code or to local storage.
4. Support litecoin: URIs like the current bitcoin: URI standard.
5. Get the current exchange rate from BTC-e for BTCLTC and BTCUSD so people can track their wallet's value against the currency they prefer.
6. The wallet needs to be releaesed under a free software license.

The easiest way to do this is probably to port de Schildbach's Bitcoin Wallet: https://play.google.com/store/apps/details?id=de.schildbach.wallet&hl=en

Bounty funds should be sent here: LTCmeAofhGojvv4Gahazxf4ZdKzdFgzuNj (http://litecoinscout.com/address/LTCmeAofhGojvv4Gahazxf4ZdKzdFgzuNj) or 1F2U53dMNhZrd2kr9zxg322GhcD2rGpHzS (http://blockchain.info/address/1F2U53dMNhZrd2kr9zxg322GhcD2rGpHzS)

I will update the bounty amount daily and will pay the bounty once I have been able to personally verify each of the requirements above have been met.

Feel free to tell developers and supporters alike about this bounty so we can get this done!

Thanks,

weex

WARNING: DO NOT USE THIS SOFTWARE

https://github.com/hank/litecoin-wallet
Source: Litecoin Wallet for Android

https://code.google.com/p/litecoinj/
Source: litecoinj

maybe ask the creator of the android wallet, mr schildbach, to integrate LTC.

Andreas Schildbach replied on March 20, 2013

So we need to suck up to those guys.

211.5 LTC added to the bounty so far.

I just ported bitcoinj into litecoinj (https://code.google.com/p/litecoinj/). I will try to merge it back into bitcoinj so both are available through it. After that, I will contact Mr Schildbach about it.

Amazing. Keep us posted!

If litecoinj gets done, I'd love to try my hand at re-coding a version of the android bitcoin client to use it.  I can release apps on Google Play currently.  Please keep me posted.

This is a great idea. i don't currently own ltc, is there a btc bounty address?

Added.

Awesome. I've put $6 for starters. Lets get this thing going! It would be even better if we can have an intergrated BTC/LTC client!

That's what I'm working towards. My litecoinj is essentially done, so now I'm trying to cleanly integrate it into bitcoinj, which would allow the current android bitcoin wallet to handle litecoin with very few changes.

I added 10 LTC to the bounty.  I personally will add more if the needed code becomes upstreamed in both bitcoinj and the Android wallet app.

This was found by Jasinlee on the devcoin wiki http://devtome.org


just thought you should know :) I don't have an android myself so can't test easily but this should be what you are after by initial browse of the page

I tested it on my Samsung Note 2, sent and received a ltc successfully.

This is a good step in making Litecoin transactions a bit easier on Android but it doesn't satisfy a very important part of the bounty.
Unfortunately, using an instawallet-style backend means the server has all of the private keys. From a security standpoint, t's ok to use these kinds of wallets for small amounts of LTC for short periods of time but they shouldn't be treated like a bank or checking account.

Adapting a version of Bitcoin Wallet that uses litecoinj rather than bitcoinj should be fairly easy, anyone can do that and collect the bounty.

However, my vision is a bit more sophisticated: Rather than having separate apps for each chain, I want to use only one app that integrates everything payment-related.

In order to get there, we need to

1. get litecoinj merged into bitcoinj
2. extend Bitcoin Wallet to support multiple wallets
3. extend Bitcoin Wallet to support multiple chains
4. get litecoin on the latest protocol

ad 1: I think it would be best if someone would speak up on the bitcoinj mailing list and explain the plans (Alex?). Usually Mike, the lead developer, has very valuable feedback. Be prepared to write a lot of unit tests, if you haven't done already.

ad 2: This is something that has to happen anyways. Its kind of a prerequisite for encrypted wallets and HD wallets, and of course also multiple chains. I plan to work on it as soon as Bitcoin Wallet version 3.0 is released (hopefully within a month).

ad 3: I had this already planned as well. Currently I'm already maintaining two apps (Prodnet and Testnet), and its a pita sometimes. The tricky part here will be memory consumption and resources in general. Its already stressful to download one chain, but multiple chains? It's safe to assume that you will need powerful (Jelly Bean class) hardware for this.

ad 4: Protocol version 70001 (Bitcoind/bitcoin-qt 0.8.x) contains a very important enhancement for SPV clients called Bloom Filters. It saves a huge amount of traffic, RAM and CPU cycles. Without these optimizations, mobile clients simply can't scale. What's the plan with litecoin for this?

Obviously one integrated app is best so I'd like to amend this bounty to add the below condition. If you contributed to this bounty or have been coding and object to this change, please post your concerns. If there are no objections within the week, we'll consider it amended.

Proposed amendment:


Thanks,

weex

In the meantime, I'd love to just get a litecoin-only version on the play store so people could start using it.  Do you think the current state of litecoinj is ready for that?  I'll start poking at that today and see if I can get it working on my phone, and if I can, I'll release it so other can try it.

Yes. In fact, no changes need to be made to the current wallet code, it just needs to be pointed to litecoinj instead of bitcoinj and it should work. (Do not put a bunch of litecoins in the wallet though, it hasn't been tested enough for me to guarantee nothing will get lost. Also the litecoin testnet seems to be dead.)

In other news, it the Bitcoinj devs are deliberating on whether they want to include support for litecoin, but they seem to be leaning towards no. If they decide against it, I may maintain a clone that has support for both.

Preliminary work done, now moving on to actual tests!

https://i.imgur.com/AMJPG5j.png

I'll add 77 LTC to the bounty. Let me know which address to send.

The address is in the first post.



I'll contribute as well. Just waiting for my BTC-e withdrawal to confirm...

/E; Contributed with 7.9 LTC

Sent 78.49 LTC  to LTCmeAofhGojvv4Gahazxf4ZdKzdFgzuNj

This is from my phone (not an emulator).  Looks like things are going well so far.  I'm going to let it sync with the blockchain for a bit now.  It's probably going to take an hour plus.

https://i.imgur.com/OuwMVQE.png

Ug syncing is going to take hours.  I guess that's the problem with having blocks solved at a higher rate.  Currently 1% done after 20 minutes or so.

First transaction worked on the phone!

https://i.imgur.com/52mOURx.png

In BlockchainServiceImpl.java, replace BoundedOverheadBlockStore with SPVBlockStore, it offers the same functionality, but faster.

Code is hosted here:

https://github.com/hank/litecoin-wallet

Feel free to fork, fix, and give me a pull request.

Ah yes that is much faster at syncing - 500 blocks in just a couple minutes.  NOW we should see the entire thing synced in around 2 hours I think.

https://play.google.com/store/apps/details?id=de.schildbach.wallet.litecoin

The app is live - feel free to try it out!  Let me know if anything's broken.  There shouldn't be too many bugs that don't also apply to Bitcoin Wallet for Android and/or bitcoinj since this app is completely derivative.

As far as bounty goes, I vote that msm595 gets half for litecoinj.  It was exactly what I've been waiting for in order to do this project!

I can't add a label to an address on my Galaxy S2. It crashes.

Other than that it seems to be working just fine. Successfully transferred a coin just now. The Bitcoin logo still shows when you receive a coin though.

Yeah that bitcoin logo svg needs fixing.  I'll get around to that soon.  Thanks for trying it.

As far as the label, I'll mess around with that.  Could you try filing a crash report?  I want to see if I actually receive it in the play developer console.  Or does it even give you the crash report popup when you restart it after a crash?

It did give me the popup, but I couldn't figure out how to send it. It gave me a bluetooth and a messenger option and I don't see how either would work.

OK weird.  I'm not familiar with how that's supposed to work.  I just tried adding an alias and it worked.  It might have something to do with the clipboard class being moved - I wonder if they removed android.text.ClipboardManager in your version.  If you could get me a logcat using adb with your phone in developer mode, that would help a lot.  If it's a ClassNotFoundException on that class, I'll try and convert the app to use it.

I just made another commit of a few things.  Mainly, I added exchange rates in BTC, RUR, and EUR to go with USD.  They're all fetched from BTC-E.  EUR took some work since there's no LTC/EUR pair on BTC-E, so I have to manually convert from BTC/EUR and LTC/BTC.  V1.01 should be pushed to the play store soon.

Thanks!

the adb drivers have gone completely haywire so I'll try re-installing those after I'm done watching Game of Thrones.

Fantastic - thanks!

We're giving this a shot. Hopefully it will be synced with the network by morning.
Great work!

I can't be bothered fixing the drivers today, so I'll do that tomorrow.

Meanwhile, I figured out how to send the report, it will however not send it to you but to schildbach.

Here's a snippet from the report:

Not sure if that helps at all.

I have been downloading the chain for a few hours and have triggered the label change bug on a Motorola Atrix but also didn't send a report. I'm a little confused as to how the app is named. Am I correct in assuming more than one app can exist with the same com.example.sub.app identifier?

[qulongweex link=topic=157932.msg1713123#msg1713123 date=1364794303]
I have been downloading the chain for a few hours and have triggered the label change bug on a Motorola Atrix but also didn't send a report. I'm a little confused as to how the app is named. Am I correct in assuming more than one app can exist with the same com.example.sub.app identifier?
[/quote]

As long as the the sub and app variables are different, there shouldn't be an issue.

Note that in the Bitcoin Wallet repo there is a bitcoinj-0.8 branch that will become version 3.0 soon. I'd cherry-pick some of the commits, like support for checkpoints.

Ah yes, and please replace my wallet@schildbach.de email address by something you own. I'm already starting to receive reports...

Got some reports of battery drain.... My copy isn't synching properly either.  http://www.reddit.com/r/litecoin/comments/1bfac2/android_wallet_for_ltc_so_that_you_might_buysell/

Awesome, and thank you very much ;)

Ah I think I know how I can fix that.  I'll try and do that some time this week, and I'll post here when it's fixed. Thanks!

Sorry about that - I'll get on that ASAP.

Syncing is definitely an issue - it takes a REALLY long time and heats up the phone (performing scrypt constantly is probably a great way to drain your battery!).  Solutions to this problem are welcome, and should probably be directed at litecoinj instead of the app.

msm595: Is there any way we can speed this up?

If everyone having trouble would file bugs here, I'd appreciate it:

https://github.com/hank/litecoin-wallet/issues

I added the ones I know about.

Thanks!

Also, I just changed the email in the Constants.java file to my own, and uploaded the APK to play, so in a while 1.02 will be available.  Please upgrade.

I've noticed the same problem, but unfortunately I don't see a way that could dramatically speed it up without skipping the scrypt (and therefore skipping the check to see if the block has valid proof of work). We could assume that every block has a valid proof of work up to a certain recent checkpoint, but I don't know what the fully ramifications of that could be. There is a checkpoint mechanism in place for SPVBlockStore, let me play around.

Skipping scrypt up to the last checkpoint seems entirely reasonable as you are already relying upon the client to be trustworthy?

Maybe it would be acceptable to users to allow faster blockchain syncing by downloading a signed (with my developer key) base block to start with, let's just say block 320,000.  That way, if I understand correctly, they could start from there and verify everything after it, still strengthening the network once they catch up.  The signed data could be distributed embedded in the app (which is also signed).  This feature could be defaulted to OFF to allow the user to elect this behavior.  Thoughts?

The trouble is off-by-default means the majority of users won't use it.  Off-by-default also means many users who try the app too easily give up because first sync is too slow, then proceed to leave an unwarranted nasty rating.  Also see Goonie's note (https://bitcointalk.org/index.php?topic=157932.msg1703864#msg1703864) that is important to this issue..


This SPV wallet will be a whole lot faster and more network efficient in syncing only after Litecoin upgrades to 0.8.  The team plans on making this a reality a few months from now.  There will be a separate fundraising effort for Litecoin-0.8.

Checkpointing is a decent idea to help with initial sync speed. For maximum safety, the checkpoint should be based on a block that is a few hundred blocks behind the current block.

Good point about off-by-default - I could have a first-time-use popup that asks "Would you like to use a checkpoint to speed up blockchain sync or verify the entire blockchain?"  Bloom filter optimization would be awesome, so I'm looking forward to that.  This app is just a simple first step that will get people using litecoins day to day, which I think was the entire point (or at least it was for me).  I'll look into implementing checkpointing soon.

The BuildCheckpoints tool from bitcoinj-tools does exactly that, although the threshold is based on time (currently one month).

There is no benefit in opting out of checkpointing - you already trust the app to do the right thing. If anything, a couple of developers should audit the checkpoints file that goes live with a release.

Well I've had a chance to test this wallet out and was able to receive and send funds out again.

I am ready to award the bounty so need an LTC and BTC address for both ralree and msm595 as I will split it evenly between you two.

Awesome. I was not able to see or verify if/where checkpoints are acknowledged in SPVBlockChain, even though this is mentioned in CheckpointManager.java: "Checkpoints are used by a {@link BlockChain} to initialize fresh {@link com.google.bitcoin.store.SPVBlockStore}s".

LTC: LQz2pJYaeqntA9BFB8rDX5AL2TTKGd5AuN
BTC: 1LSbhxShMmymNQ1Li5qd7pYUgrMUcVTokc
Thanks :)

LerikguvK4nTvhk5XUp8ofg2JgLqAGnBV3
1MANaTeEZoH4YkgMYz61E5y4s9BYhAuUjG

Thanks for putting this together!

If you figure that out, let me know what I have to do to implement it.  The blockchain fully synced and the app is working great for me now.

Download to my android , its. ... hot  ;)

Payments complete. Well deserved for you both!

http://litecoinscout.com/tx/c180780f9ef2ab2974a353bcf9eedfc1db6a6cb6b844c62f00f5a2bd8a73a175

https://blockchain.info/tx/640cac96ce7d4b90fe06709289d3db5cb8e5cab08e33bb07b43ebd8dc5b7f694

it turned out I had my wifi off,  now it's all in sync and feel really cool  8)

thank you and congratulations on the nice job.

Cheers!  Glad I could be of help.  With the massive value increase of Litecoin, it's pretty exciting to have another way to transmit and store it.

msm595, what will the litecoinj maintenance plan be?

TD mentioned that he's open to code changes in bitcoinj that would make it easier to maintain a fork.  Perhaps you folks could work out a way to parameterize most of what is needed for litecoinj into a tiny subclass?

what is the github address for litecoinj?

I'm not quite sure what the plan will be. Given I'm a student, I'm mainly free on weekends. The easiest change in bitcoinj would probably be the one that allows bitcoinj to offer multiple coins: making NetworkParameters abstract and giving litecoin and bitcoin a class off of that. That's the main change anyway, blocks would need to check if they should be hashed with scrypt or sha256, but that is a matter of a simple method call.

Litecoinj isn't on github (though in hindsight, it probably should be / it may be moved there). Currently it is located at https://code.google.com/p/litecoinj/.

Ah, I see bitcoinj is at code.google.com too. It's fine to be hosted there if it's easier for you.

Great work to you and ralree.

Github does make quite a few things easier.  Forking and pull requests, mainly.  Issue tracking is nice too.  I hope the changes are made in bitcoinj to support other cryptocoins in a good way.  I'd love to have a BTC/LTC/PPC/NMC/TRC/FRC/NVC/BBQC wallet! :D

Really? Access to my camera and microphone.  Will not use.

Camera to take a picture of QR codes, as that's the safest and quickest way to copy someone else's address if you are paying them.  You *really* don't want to typo an address as is likely still a valid address and the money could disappear forever.

Not sure about microphone.  You can look in the source code yourself to figure out why it is there.  Might be an accident.

(I didn't run it myself yet.  I want to do a lot of tests on testnet personally before relying on it for larger amounts of LTC.)

If you are so fantastic at knowing what is so wrong, can you figure out your own app and create it and stop trolling. You are not going to earn any friends starting out in this community talking crap to everyone since you think you know better. Where is your portfolio? Why shouldnt we all just ignore you since you are going around insulting the devs that are making progress on the apps you keep talking about.

All the permissions are listed in the manifest:

https://github.com/hank/litecoin-wallet/blob/master/wallet/AndroidManifest.xml

The definitions are here if you want to see what they do:

https://developer.android.com/reference/android/Manifest.permission.html

I have no idea why the CAMERA permission would give access to the microphone, but I didn't change the permissions when I ported from the bitcoin app, so it has exactly the same access.

Dear Litecoin Wallet Android dev, please check this thread for a problem I'm encountering with the update: https://bitcointalk.org/index.php?topic=172384.0

Thanks - sorry you're having trouble.  I'll look into it.

There was a bug in versions prior to 1.05 - the fee was set very low (0.0005 LTC) so transactions going out of the app were taking a long time.  The fee in 1.05 and up defaults to 0.01LTC.  I'm currently unable to scale it to the size of the transaction output, and I haven't found where in the code bitcoin wallet for android does that either (maybe it doesn't need to...).  Any assistance would be much appreciated!  Please send me a PM if you think you can help.

msm595: any idea if litecoinj can help here?

According to https://code.google.com/p/litecoinj/source/browse/core/src/main/java/com/google/bitcoin/core/Wallet.java#1737 Litecoinj will not calculate any fees for you. Your best reference would be https://github.com/litecoin-project/litecoin/blob/master/src/main.h#L545 which is where litecoind/litecoin-qt calculates its fees.

Since I doubt this is miners being picky, it's probably the minimum fee needed to have other litecoin nodes relay. In looking at this before, I found there's a limit of how many kb/s of low or no fee transactions that a node will relay. The CENT (0.01) also seems to be important for not triggering massive fees. As in, if the client doesn't send subcent outputs the 0.1 ltc fee shouldn't be required.

Bug Report:

Camera/QR code feature does not work with Samsung Galaxy S3.  Not seen that error before, but it happened. 

Just found this thread while searching for a ltc wallet for android. Any idea if this will be updated to support the new ltc qt?  I'm pretty new to all this, but I'm wondering if I set this wallet up, it will have a diff address than the wallet I have on my desktop right? Is there a way to clone the wallet so I can use both devices with the same wallet? (:

It's not a bug, it's a feature (-:

Rather than "cloning" a wallet just keep two wallets and move funds between them using standard transactions.

It's like with cash money: You either have it in your wallet with you, or stored at home in a cupboard, or stored in the safe at your local bank. It's not at all these places at the same time.

I can confirm that this wallet works for what I need but you should know that it doesn't calculate fees exactly like Litecoin-QT so you will probably want to err on the side of caution for fees. I generally do not have a problem if I include 0.01* as a fee but going with no fee is likely to cause a relaying problem that this wallet will not recover from gracefully.

*Edit: I see that this is likely not a safe fee amount to include and will likely add 0.02 at a minimum. It should be noted as well that this app is not currently being maintained so use it at your own risk!

Alright!  Installing now :D

The standard fee is 0.02 LTC per KB assuming they have no outputs smaller than 0.01 LTC.  Unfortunately, 0.02 LTC fee is no guarantee of it working, as this ancient version of Android Wallet has no way of knowing the mandatory fee based upon the transaction size and coin age.

WARNING: DO NOT USE THIS SOFTWARE

Generally, this wallet is the result of a weekend bounty back in March that never was complete (incapable of calculating minimum fees) and was not improved since.  Others intend on a long-term maintainable port of bitcoinj and the Android Wallet for the Litecoin protocol that pretty much is starting from scratch.  This current wallet owner on the Android market is invited to join them or to step aside.  Confusing users with a dangerous, unfinished and unmaintained product is not good.

This wallet is currently vulnerable to creating addresses with low entropy. This means any funds managed by this wallet are at risk of theft.

For more information, see the Android vulnerability thread: https://bitcointalk.org/index.php?topic=271831.0

Edit: This issue has since been fixed. There is another issue with fee calculation(causing transactions not to be verified by the network) that means this wallet should be used with caution.

What is the status of this project and the bounty?  I am finding it relatively easy to fork the bitcoinj and bitcoin-wallet projects and modify them for any proof of work coin.

The bounty was claimed in March.  The resulting wallet was incomplete and screwed many users with bugs.  We are in the process of rewriting the entire stack to be long-term maintainable.

what about this one? https://bitcoinstarter.com/projects/104

Any idea how to contact that person?  They are very late in delivery.