Bitcoin Forum

Over the summer the Mycelium dev team has been working hard to make Mycelium 2.0 a reality. Our 200+ beta testers have given us great feedback and today, our biggest and most significant wallet update has finally been released for everyone.

Direct download: https://mycelium.com/bitcoinwallet
On Google Play we use staged rollout, where it is released gradually over the next few days: https://play.google.com/store/apps/details?id=com.mycelium.wallet



New Features:

* Added support for BIP32/BIP44 compliant HD accounts based on a single master seed
* A much simpler backup that uses a word list to backup all your HD accounts (BIP39)
* No more address reuse, which greatly increases privacy
* You can label transactions in transaction history
* Transactions can be created with poor or no internet connectivity, and be broadcast later
* You can now have unlimited number of watch-only addresses
* Cold Storage spending now let's you spend unconfirmed inputs


What does HD mean?

HD is short for Hierarchical Deterministic. Typically, bitcoin wallets generate each new bitcoin address from a unique random number, requiring a separate backup of each new address. To avoid losses from lack of backups, such wallets use a single bitcoin address for all your transactions. HD wallets instead use a “master seed” (a single large random number), to derive all future bitcoin addresses sequentially from that single seed. This means that you only need to make a backup once, and all the keys generated by an HD wallet can be restored at any time in the future just from that single master seed. HD wallets greatly improve your privacy by being able to keep generating new addresses. If you use the same address continuously all your transactions will be associated with a single address, and because all bitcoin transactions are public anyone can see what addresses you are sending funds to, and calculate your total balance. With an HD account new addresses are created whenever you send and receive funds, making your transaction activity and total balance very hard to track.


But I liked it the way it was! Will I have to change the way I use it?

All your keys, addresses and address book entries will be retained when you upgrade your app. The tab previously named “Keys” has been renamed to “Accounts.” Your old bitcoin addresses will become single address accounts, and you can continue to use them as before. We do advise that you switch to new HD accounts, though. You will also see your first empty HD account, which you can start using right away.


What about previous backups? Do my old ones still work?

Yes. You can still import keys and addresses you backed up with the previous version of Mycelium Wallet. However, we have removed the ability to create backups of single keys, or create new single addresses accounts. Instead, we advise you to backup your master seed and move your funds to the new HD wallet. As long as you keep your old backups, though, you will be able to recover your legacy accounts using Mycelium. To import a private key, switch to the “Accounts” tab, tap the icon with a key and plus symbol in the upper right corner, and select “Advanced”. Then scan your encrypted private key and enter the password.


Will I be able to continue to use my current Local Trader identity?

Yes. Your Local Trader identity will get carried over to the new version when upgrading along with your private keys.


How do I make a backup?

To create a backup, either tap the “Secure My Funds” button on the main page, or choose “backup” from the menu. You will be shown a list of words, one after the other. Write those words down with pen & paper. You then have to type in the words again, to make sure you got everything right. Store this word list in a safe place! Anybody who obtains this list can access current and future funds in your wallet!
Note: The backup procedure only backs up your HD accounts. Your classic single address accounts are not part of this backup procedure.


How do I restore a backup?

If your phone is lost or damaged you can make a fresh install of the mycelium wallet on a different device. Upon startup, choose “Restore Backup”. Choose 12 as the length of your word list, and let the “password” checkbox unchecked, and proceed to enter your word list. This recreates your master seed and automatically creates and synchronizes your first HD account. It might take some time until your first account is synchronized and the balance updates. If you had more than one account, navigate to the “Accounts” tab, tap the button with a key icon and plus on the upper right corner, and choose “Add HD Account” to re-create your second account, etc. Note: This procedure only restores your HD accounts. To restore your classic accounts you have to manually import each key/address by going to the Accounts tab, click the + button, select Advanced, and then Import. If your previous Mycelium installation had a Local Trader account you can recreate your trader account and data by clicking “Buy/Sell Bitcoins”, select the “My Info” tab, click “Create” and select the account that your local trader identity was associated with.


Can I restore a BIP44 wallet created with other software?

Yes. When you start a fresh install of the app you get the option to restore a backup. You can choose between word lists lengths of 12, 18, or 24 words, and also supply an optional password in accordance with BIP44. This way you can restore all HD accounts generated by other wallets compatible with BIP44 and BIP39. For instance, this allows you to import your TREZOR word list in case your device was lost or damaged so you can quickly move your funds to safety.

cool to see another wallet avaiable for hardware wallets like trezor!
I will test it

@Rassah Being such an old member of BitcoinTalk, dont u know where these kinda threads belong ? Why do u always post these under Bitcoin Discussion ? This belong to Service Announcement !!!

But it is not a service - it is an app

Well done guys on this release, love the new version.

Been testing it since it was rolled out on beta and thus far not a single problem. Definitely the number one wallet for my phone.

Being an old member, I know that a lot of people stick to their own favorite sections, and occasionally check the main thread, so I post there in the hopes that some people who may have never heard of Mycelium will see it before it's buried under an avalanche of new topics.

I love the way to autocomplete the seed verification to avoid some kind of keylogger, very nice.

Now it  is the BEST android wallet out there

i hope you were thinking about trezor ( host usb)  compatibility, coinshuffle or similar and BitID to become  the PERFECT wallet


Good work guys !

thanks for the todo list. Bitid is functional, but we need to do some finetuning on the way we derive the actual keypairs from the seed.

coinshuffle is the most complex task out of this list, but the motivation to do it is big.

hehe, you're welcome, and I'm glad to hear you  are working to improve it even more .

offtopic: Any ETA for the t-shirts shipping?  my freaky side is looking forward to wear it  ::)

Sounds like a great update.
As soon as it rolled out to my play store I'll give it a try.

Still Android only?  (Fantastic job tbw.)

There will eventually be an iOS version.
Planning is in progress.
No details available yet :)

Hmm looks great. I'm so used to android bitcoin wallet by andreas but this looks equally good as well. Nicely done

This has cold storage spending that let's you spend directly from a paper wallet (BIP38 encrypted private keys supported as well), and LocalTrader, which is like LocalBitcoin, but built right into your wallet, and much more secure and anonymous.

QR scan only, no text import (nudge, nudge.  You have no idea how this would make my life easier).

Any thoughts on expanding LocalTrader, so it could offer functionality similar to i.e. bitpay? https://bitcointalk.org/index.php?topic=293472.msg9177218#msg9177218

Lovin Mycelium 2.0

Has anyone tried taking the 12 word backup between Breadwallet(for iPhone) and Mycelium?

I can't seem to get it to work. I have a BIP32/BIP44 wallet on Breadwallet and I have the 12 word BIP39 backup. I downloaded a fresh Mycelium and asked it to restore from those 12 words. It shows as a zero balance wallet with a different receive address than the first one that was shown by Breadwallet.

Any ideas? compressed vs uncompressed? Anything else?

Does the HD wallet use compressed keys? As in, the private keys start with the letters L or K?

The transactions tab used to show the to/from address(es) and, more importantly, any custom labels. What happened or where do I need to look now?

For example, I get dividends from a particular BTC address, so it was always handy to look at the list of transactions and see "xyz div" under the relevant payments.

Breadwallet doesn't seem to expose the private keys, only the twelve word seed generator. My installation's current (public) address starts with 16E. This is the second address it generated. The first (which received some funds) started with 1PL.

The first address showing on Mycelium (using the same 12 word seed generator) starts with 1EJ.

breadwallet (http://breadwallet.com) isn't using the same BIP32 tree structure as mycelium, so the backups are not compatible. I have heard that hive is using the same structure as breadwallet, though I don't recommend typing your backup phrase into multiple wallets and devices. Security of your wallet seed is absolutely critical. Every wallet and device you use it with increases the chances that one of them has a security hole or is infected with malware. breadwallet is built to a very high standard of security. Your seed is only stored in the iPhone secure enclave which is hardware encrypted and even hardened against EM side-channel attacks. Other wallets decrypt your keys in the browser with javascript, and other platforms are far more susceptible to malware.

Ah.. Thanks for the clarification.

As for your other comments, I agree, but I absolutely need to know I CAN go to another platform if I have to. Preferably many platforms. With paper cold store I can, but with 12 word seeds I still can't.

There is nothing wrong with trying to restore backups on another platform when the wallet has trivial amounts in it. That way I know I can do it if I have to some day. For example, what if Breadwallet is pulled from the AppStore?

Fair enough. As I mentioned I've been told hive is using the same structure, but I haven't tried it personally. Apple hasn't ever removed apps from individuals phones even if the app is pulled from the app store, but it's always good to be sure. If anything like that ever happened I would quickly release a tool to get your funds out, and it's open source as well and using the default BIP32 tree described in the BIP32 examples, so any developer could do this.

I also plan to build an android version of breadwallet using the trusted platform module to attain a similar level of security as the iOS version.

All this confusion about incompatible wallets calls for a look at bip 39.  The process starts with finding 128 bits of entropy ("ENT") and builds from there.  The bip sets out some fairly simple steps for generating a wordlist from ENT.  So far so good.
Then instead of creating the wallet seed from ENT, the simplest and best course, it goes like this

To create a binary seed from the mnemonic, we use the PBKDF2 function with a mnemonic sentence (in UTF-8 NFKD) used as the password and the string "mnemonic" + passphrase (again in UTF-8 NFKD) used as the salt. The iteration count is set to 2048 and HMAC-SHA512 is used as the pseudo-random function. The length of the derived key is 512 bits (= 64 bytes).

These steps are unnecessary, create extra work, and may lead to complications.
Encrypting your wordlist is all for the best, but please don't interpose that encryption between the originating entropy pool and the master seed/private key of the HD wallet.  Basically you are encrypting entropy.  It doesn't work like that.  It works like this:

The entropy is the seed.  
Use it:  entropy --> seed
ENT --> sha256 hash --> master privkey

This was added so wallets could generate the seed even if they don't have or can't hold every word list, like trezor. I agree that it's less than ideal.

 
It would have worked about as well to encode the 128 bits of needed entropy in a string of 22 base64 or base58 characters.  There's your backup.  Easy to decode and get the entropy binary back, which can act as the seed for the wallet.  
And there's nothing to stop any wallet designer, who so wishes, from encoding the binary in a word list per bip39.  For interoperability among different wallets with different dictionaries, use the 22 character string... any wallet, even one as limited as trezor, is sure to have enough memory and processing power to decode its own word list!

Bip39 was kludged into the wallet architecture between the entropy and the master key -- where it isn't needed, and can only cause problems.  Will we be stuck with this contraption in every wallet from now on?

Just in case I'm not getting through:

Whoever came up that whole mess described in the section of the mediawiki titled "From mnemonic to seed" was wasting everybody's time.  The idea that you have to go to such lengths to avoid storing a library of bip39 dictionaries is an illusion.  Merely store your own dictionary; when you need the binary, decode the wordlist.  Simple as that!

HD wallet designers have followed bip39 without giving it a moment's thought or considering maybe the bip's badly designed. But it is the worst kind of bad design; it's a strategic error not a coding blunder, so people operating on autopilot don't see it. Then it gets coded into wallets, and you're stuck with it forever.  And we'll have all kinds of headaches making HD wallets compatible.

I'm staying with legacy accounts, for now.

Is there any easy way of scanning transactions (i.e. where you see the custom labels created for specific addresses)?

I have Mycelium Wallet 2.1.0

I can't figure out how to not reuse the receiving address... The same one always shows up...

If it's an HD account, the receiving address will change automatically once you receive coins to it.

I would also like to request that Mycelium add support for the Trezor hardware wallets with the use of an On-the-Go cable. I believe the Trezor team has already put some code on GitHub as an example of how to incorporate it into multiple wallets. Thanks for your consideration.

Sure, no problem.
Watch out for a beta release soon :)

Awesome! Thanks for being so quick and willing to implement support for the trezor :D

It's your lucky day. I received an email today (or was it yesterday) about the new beta version:

Just noticed the following in MyCelium, not sure whether it's a bug or not.

The total in the HD account section and the total for the other accounts show 0 BTC yet there is some dust in there. Total at the bottom displays correctly.

If I change it to display in USD then the total show up correctly in each section.

http://screencast.com/t/ee7PusqA2r

EDIT: See the image is not showing.

On the Account page of MyCelium I have my HD account and some other accounts. The total for each section shows up as 0 BTC even though there are balances on those addresses which are shown under each address. The total at the bottom shows up correctly as x.xxx BTC. When changed to USD all totals shows up correctly.

I'm moving from iOS to Android and looking at this wallet.

Does it support finger print readers in addition to Pins?

looks great, can we expect this coming out for iOS soon? as a iphone user im sad i wont get to experience this .

There is a Mycellium wallet in the App Store. Give it a try. Although, I heard some bad things about it (bugs) when it first came out so I stuck with Blockchain.info and Breadwallet on iOS.

It's still a bit cranky now by the sounds of it. Best to steer clear and stick the proven ones.

ya i tried using it, its really not for me. all it can do is send/receive and backup/recover. it doesnt have the goodies that the android version has like importing or exporting keys or importing hd wallets

I recently reset my phone to factory condition and forgot I had Mycelium with a small share of a bitcoin on it. Not too much, so it won't really harm me if it's lost, but enough to be annoying.

Went looking through my notes for a backup and found something in this form created in July 2014 with whatever version of Mycelium was current at the time:
xxx xxx xxx xxx xxx x
Every x is a seemingly random capital letter. After re-installing Mycelium, I can't find a way to enter this as a seed code, instead it asks for a word list of at least 12 English words.

Does anyone recognize what this backup code is and can tell me how to use it?

This code is for an old style paper (PDF) backup.  If you have it, look for the encrypted key QR code in it, scan it with Mycelium, and it will ask you for this code.  This code is useless without the printout or PDF.

If you can’t find the printout, chances are you may still have the PDF somewhere, as it was generated at the same time as this code.  The file name pattern is mycelium-backup-*.pdf, where * stands for the date and time.  It may even be somewhere on an SD card or some data partition which is not cleaned by a factory reset.

Thanks! Very helpful.

Hello guys and girls. I want to mine bitcoin with Hashflare. So i made a Mycelium bitcoin wallet. Now i have this little problem... This is so confusing to me; What address do i have to provide to the mining application when they ask for wallet address ? is it the mycelium public key in Account button or the key that is shown in Receive button ???

Thanks in advance guys/girls!! Your help is much appreciated.

Your receive address.  Keep in mind, it will change every time you receive bitcoin. But, all the addresses remain valid.

Might want to use a legacy (static) address for that, especially with fees so high now.

Why? I thought multiple addresses didn't increase the fee because multiple payments are always counted as a new input regardless of the number of different addresses?

Maybe I'm wrong about the fees.  I was thinking that sending from a single address would use a smaller transaction than sending from multiple addresses.

I'm pretty sure the inputs are the same size whether they come from one address or multiple addresses. So, the size of the transaction should be the same either way.

But, don't make the mistake I made by creating a new "Account" (derivation path) for your mining or small receives, because then when you spend from you main wallet account, it can't grab a small output from the other account to fill the tx if needed, and will have to break up a larger output you might have sitting in the main account.

Yes, you are wrong. The data size of the transaction has nothing to do with the addresses being used. It is all to do with the number of inputs and outputs. So, a transaction that uses 10 inputs from 1 address, will likely have the same data size as a transaction that uses 1 input from 10 addresses... they both have 10 inputs.

There will be some variation depending on compressed vs. uncompressed addresses and legacy vs. segwit, but in general it won't matter (from a data size perspective) if you used one address or 100 addresses.