Mycelium Bitcoin Wallet

[Jan]

The Mycelium Bitcoin Wallet is a Bitcoin wallet for Android and the successor of BitcoinSpinner.
It was initially announced in the BitcoinSpinner forum thread as an early beta.

We have received a lot of great feedback over the months, which has allowed us to dramatically improve the wallet. It is now deployed on more than 2000 devices.

Overview:

• Sources available for review: https://github.com/mycelium-com/wallet
• 100% control over your private keys, they never leave your device unless you export them.
• No block chain download, installs and runs in seconds.
• Ultra fast connection to the Bitcoin network through our redundant super nodes.
• Designed for simplicity, but with unique advanced features in expert mode.

Features:

• Cold storage spending: Spend directly from paper (demo)
• Import private keys using SIPA and mini private key format (Casascius private keys) from QR-codes or clipboard
• Export private keys as QR-codes, on clipboard, and directly to printer using external SD card (demo).
• Watch-only addresses
• Key control using Active and Archive key set.
• PIN protection
• Multiple Bitcoin denominations: BTC, mBTC, and uBTC
• View your balance in 164 fiat currencies
• Switch between Bitstamp, MtGox, or weighted average when getting BTC/fiat exchange rates
• Switch between BTC/fiat when sending coins
• Switch between BTC/fiat when making a payment request
• Address book for commonly used addresses
• Transaction history with full transaction details.
• Tor connections using Orbot with SOCKS proxy
• Integrated QR-code scanner
• Share your bitcoin address using Twitter, Facebook, email ...

...and more.

apetersson and I have been working full time since April developing this wallet. We hope you like it and leave a 5 star review on Google Play.

If you want to get early access to new releases please join the Google+ group Mycelium Beta Testers

TL;DR
Try out the Mycelium Bitcoin Wallet: Google Play or direct download
The sources are published here: https://github.com/mycelium-com/wallet
We hope you like it and leave a 5 star review 

EDIT: Release notes for version 1.3.3:

v1.3.3 was released to Google Play store, github, and our site.

The list of changes from last regular release include:

* Generic scan button in the main view - Use this to quickly scan QR codes to send bitcoins. In the future, this may be used to quickly log into websites with BitID.
* Improvements to barcode scanning with flashlight toggle and autofocus setting
* Email notifications for LocalTrader - Google Push Notifications system is still kind of unreliable, and we can't fix it because it's Google servers that are having issues, so this is a fix until we figure out something better.
* Fixes and connectivity fallback for dns issues - A few days ago we had an issue where our domain name, which is pointing to our servers, was temporarily turned off by our provider while they verified that we are who we say we are. Should this happen again, wallets will switch to contacting our servers with their IP numbers directly (this is also likely temporary, until we move everything to Tor)
* Various crash fixes

We think that this will be the last feature update for the non-HD version. Stay tuned for an upcoming Mycelium HD release.

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[Jan]

Version 0.8.1 is out. Get it on Google Play or direct download

• Adding 140 fiat currencies, 164 supported fiat currencies in total
• Choice of which exchange to use (Bitstamp/MtGox/weighted average)
• Expert Mode: This allows us to hide some of the more advanced stuff to make the wallet even easier to use for newcomers.
• Smooth and snappy swiping between balance and transaction history
• Got rid of one step/screen in the send wizard
• Transaction details now linking directly to blockchain.info
• Improved functionality for pasting amounts when sending coins

Enjoy

[evoorhees]

This has become my preferred android wallet. Been very happy with it so far. Hopefully it'll look a little prettier some day, but in terms of function and reliability I have no complaints at all

[apetersson]

Thanks for your support

Don't worry about the UI falling behind. We do have grand plans to overhaul it.
If you have any specific suggestions or something is bugging you, please don't hesitate to post here or write to developers@mycelium.com


if you want to see the early beta builds you need to join the google group AND activate beta builds at https://play.google.com/apps/testing/com.mycelium.wallet

[westkybitcoins]

Version 0.8.1 is out. Get it on Google Play or direct download

• Adding 140 fiat currencies, 164 supported fiat currencies in total
• Choice of which exchange to use (Bitstamp/MtGox/weighted average)
• Expert Mode: This allows us to hide some of the more advanced stuff to make the wallet even easier to use for newcomers.
• Smooth and snappy swiping between balance and transaction history
• Got rid of one step/screen in the send wizard
• Transaction details now linking directly to blockchain.info
• Improved functionality for pasting amounts when sending coins

Enjoy

Nice!

Moving the advanced features to an Expert Mode should really help in drawing in new users.

[jim618]

I was copying an address to Mycelium yesterday and accidentally copied a trailing space.

In Mycelium the 'add address from clipboard' was disabled - presumably as the clipboard content did not parse to a Bitcoin address. It would be worth trimming the whitespace as I ended up doing it manually.

[Stephen Gornick]

Incidentally, I'm still willing to test this when repackaged for Blackberry 10.

[Newar]

I had Mycelium initially installed from the website. Now however it shows as a Google store update too. Is this intended?

[Jan]

I was copying an address to Mycelium yesterday and accidentally copied a trailing space.

In Mycelium the 'add address from clipboard' was disabled - presumably as the clipboard content did not parse to a Bitcoin address. It would be worth trimming the whitespace as I ended up doing it manually.

Thanks Jim. All fixed. Going into the next release.

[Jan]

Incidentally, I'm still willing to test this when repackaged for Blackberry 10.

Incidentally, I think apetersen is still waiting for you to reply on whether you would like to help us test on Blackberry 

Please consider packaging it for BlackBerry10 too.

the plan is to have the application in beta for some time and then incrementally improving user experience.

we certainly consider creating a build for Blackberry 10, but we don't have a device for testing. would you like to help us running the tests on your device?

Blackberry has this online tool for converting and re-packaging Android APK files: https://bdsc.webapps.blackberry.com/android/bpaa/
I tried it out and the tool says that the Mycelium app is compatible. So far so good.
My problem: I don't have a device where I can test it

Stephen, would you like to try out the conversion and test it on BB? Here is the latest APK.

[Jan]

I had Mycelium initially installed from the website. Now however it shows as a Google store update too. Is this intended?

The APK in the play store and on the web-site is the same, and signed under the same certificate. I guess the play store app looks for installed packages on your device and sees whether the store has a newer version signed under the same certificate.

[Stephen Gornick]

I tried it out and the tool says that the Mycelium app is compatible. So far so good.
My problem: I don't have a device where I can test it

Doh!  Here's what I get:

Whoops, it looks like your system may not be supported. Currently the online packager only supports Windows and Mac OS.

- https://bdsc.webapps.blackberry.com/android/bpaa/applet-permissioning

I'll be giving it another try in a few days when I have access to a Windows system.

[Newar]

What is the red big fat X next to the send-to-address supposed to mean? Had me confused there for a bit as I thought it may indicate an incorrect BTC address.

[btc4ever]

Does mycelium use SPV to validate transactions, or relies on a central server, or....?   Perhaps you could add that to the description.  thanks.


Maybe also add mycelium to this page?
https://en.bitcoin.it/wiki/Thin_Client_Security

[Jan]

What is the red big fat X next to the send-to-address supposed to mean? Had me confused there for a bit as I thought it may indicate an incorrect BTC address.

Clicking the red X clears the address and allows you to specify another one. I agree that it looks a bit intimidating. I see two options:
1. make the red X smaller
2. remove it entirely - to enter another address you can click the back button to start over.
I am leaning towards 2. I don't think you are likely to change your mind on the receiving address, and if you really change your mind you just click back to start over.

[Jan]

Does mycelium use SPV to validate transactions, or relies on a central server, or....?   Perhaps you could add that to the description.  thanks.

Maybe also add mycelium to this page?
https://en.bitcoin.it/wiki/Thin_Client_Security

Mycelium connects to one of our super nodes to synchronize its transaction history and unspent outputs inventory. Whenever the client starts it connects to a random server, and automatically fails over to another server in case of downtime (client side loadbalancing). Communication is secured with HTTPS using a certificate that is pinned in the wallet software. There are currently 2 servers located in two different datacenters. They are are 100% redundant, and more servers can be added as required to improve scalability and redundancy. Each server connects to 500+ Bitcoin nodes, which make your transactions propagate swiftly across the network.

So to answer your question. Mycelium does not use SVP mode, but relies on a set of servers that are very well connected to the Bitcoin network.
The servers do not have your private keys and do not hold any usernames, passwords or any other secret stuff. They just work as s super optimized index on top of the Bitcoin network.

In case you are worried about anonymity you can use the SOCKS proxy feature and connect through Tor using Orbot.

Making an FAQ that addresses this and many other topics is on the list

[Newar]

What is the red big fat X next to the send-to-address supposed to mean? Had me confused there for a bit as I thought it may indicate an incorrect BTC address.

Clicking the red X clears the address and allows you to specify another one. I agree that it looks a bit intimidating. I see two options:
1. make the red X smaller
2. remove it entirely - to enter another address you can click the back button to start over.
I am leaning towards 2. I don't think you are likely to change your mind on the receiving address, and if you really change your mind you just click back to start over.

I would vote for removal too. I mean when I plan a tx I am _ready_ at this point, i.e. I got the address from a QR code or pasted from the clipboard. The decision which address to use happened way earlier, before I hit the send button.

[btc4ever]

Jan, thanks for the explanation.  Can you comment on why this method was chosen over SPV, which as I understand it would not need to rely on a trusted server?

Mycelium connects to one of our super nodes to synchronize its transaction history and unspent outputs inventory. Whenever the client starts it connects to a random server, and automatically fails over to another server in case of downtime (client side loadbalancing). Communication is secured with HTTPS using a certificate that is pinned in the wallet software. There are currently 2 servers located in two different datacenters. They are are 100% redundant, and more servers can be added as required to improve scalability and redundancy. Each server connects to 500+ Bitcoin nodes, which make your transactions propagate swiftly across the network.

So to answer your question. Mycelium does not use SVP mode, but relies on a set of servers that are very well connected to the Bitcoin network.
The servers do not have your private keys and do not hold any usernames, passwords or any other secret stuff. They just work as s super optimized index on top of the Bitcoin network.

In case you are worried about anonymity you can use the SOCKS proxy feature and connect through Tor using Orbot.

Making an FAQ that addresses this and many other topics is on the list

[Jan]

Jan, thanks for the explanation.  Can you comment on why this method was chosen over SPV, which as I understand it would not need to rely on a trusted server?

SVP clients have some shortcomings because of the way SVP mode works. With SVP you only observe transactions being sent-from/received-to your addresses from the point in time where you create the corresponding key in your wallet and start tracking the blockchain. Because of that you cannot import arbitrary keys and start spending from them, as you would have to scan the block chain back from the genesis block to determine which funds you have and what your transaction history is.
The Mycelium wallet has very strong key management features such as importing arbitrary private keys and cold storage spending. Those features are not feasible with a SVP client.

edit: spelling

[Michael_S]

Thanks for your support

Don't worry about the UI falling behind. We do have grand plans to overhaul it.
If you have any specific suggestions or something is bugging you, please don't hesitate to post here or write to developers@mycelium.com

Some illustrations how a comfortable GUI could look like after scanning the QR code, and also including comfortable tipping in "restaurant/pub" scenarios (in countries where tipping is common, like USA, central Europe, ...):

PDF file: http://de.scribd.com/doc/168360248/Bitcoin-App-Tip-Diagrams

Images:




(Note: One could make it even more comfortable by skipping the first (simple) "spend" screen and pre-occupying some fields with adequate values by enhancing BIP 0021 with a "tip" and "tipaddr" parameter, but it seems that such enhancements of BIP 0021 are not welcome by the bitcoin developers, even though "tipping" is a very frequent use case in daily life.)