Mycelium Bitcoin Wallet

[pm7]

I don't know how you'd sign transactions on a phone by way of an external device that stores your private key (e.g. how Armory does it), but it would be awesome to see.

https://bitcointalk.org/index.php?topic=610453.0 "Sigsafe: A NFC key tag for signing bitcoin transactions"
I think Newar wasn't writing about external device, rather something like paper wallet and existing read-only addresses in Mycelium.

Video in the description of Mycelium in Google Play is a bit outdated (e.g. backup generation and verification).

[lyth0s]

The new Mycelium HD works beautifully, thanks guys!

[Newar]

I don't know how you'd sign transactions on a phone by way of an external device that stores your private key (e.g. how Armory does it), but it would be awesome to see.

https://bitcointalk.org/index.php?topic=610453.0 "Sigsafe: A NFC key tag for signing bitcoin transactions"
I think Newar wasn't writing about external device, rather something like paper wallet and existing read-only addresses in Mycelium.

No, I was talking about two phones. One in the shop set up as watch-only. The cashier uses the "Receive" button, enters the amount in local currency and displays the QR code to the customer. The other phone (or "device") safe with me and with the full set of private keys. This was easily done pre-HD, looking forward to see it in HD too!

[...]
Synchronizing takes a bit longer the first time, because for HD some address discovery has to take place, but it should be fast for the next times.
[...]

Synchronising definitely takes noticeably longer "all the time" with the new release for me.

[Newar]

I look forward to such a feature. I don't know how you'd sign transactions on a phone by way of an external device that stores your private key (e.g. how Armory does it), but it would be awesome to see.

Apart from using NFC as linked, it also can be done via an "OTG" cable and Trezor for example. There is development under way for this. https://bitcointalk.org/index.php?topic=122438.msg8179813#msg8179813

[ZephramC]

Great!

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.

Just for the sake of symmetry... Can I also use word list generated by Mycelium during HD account backup as input for Trezor?

Yes, but have in mind that Trezor provides higher security than what you can get on an android device, and by having the same master seed on two platforms gives you the least common denominator... Security wise.
So, I would only do that if my phone was broken.

Of course. Having the same master seed on two platforms is not the intended application. But in the case your phone is stolen/compromised (or broken) it is faster to use Trezor (if you have one) to temporarily protect your BTC than to get another android phone and install Mycelium. I know you can use backuputil too
I have both Mycelium and Trezor and I intend to use them both :-).

[hgmichna]

For HD accounts, you get a new receiving address whenever you receive money.

When I tap the Receive button, Mycelium shows the same HD wallet address, the only one I have, not a new receiving address. The statement above does not seem to be true for my Mycelium installation.

[hgmichna]

All your keys, including local trader identity, will automatically get migrated when you upgrade.

No. None was migrated to the new HD account. They were just kept, not migrated.

If you want your local trader identity back, import the corresponding key, select it, and hit create in local trader my info tab.

I did not have to do that. The Local Trader wallet remained in place, as expected.

The question remains, how can I migrate the Local Trader wallet to the HD account?

The only way I can see is to delete my Local Trader status completely and create a new one. That, however, would lose everything, history and rating.

I guess there is currently no other way. Of course I can keep the old account, but that would mean not having any of the HD advantages.

No very big deal in my personal case, but I guess that a successful long-term trader might hate to lose all his credentials.

[Newar]

For HD accounts, you get a new receiving address whenever you receive money.

When I tap the Receive button, Mycelium shows the same HD wallet address, the only one I have, not a new receiving address. The statement above does not seem to be true for my Mycelium installation.

That confused me initially too, but after you have received for the first time, you will see a new address every time.

[...]
I guess there is currently no other way. Of course I can keep the old account, but that would mean not having any of the HD advantages. [...]

IIRC, the address for Local Trader only works as a sort of identifier. You can send / receive BTC to any address you please.

[trasla]

You cannot migrate keys into an HD account.
And HD account has a defined structure with a deterministic set of keys being created.
You can keep your keys - when I wrote they get migrated, I was referring to the fact that Single Address Accounts are created from them, so you get to keep them in your wallet.

You cannot migrate a local trader identity to another key.
This is due to the fact that your local trader chats are encrypted based on that key.
You can create a new identity based on an HD account.
But there is no downside to just keeping your local trader key and identity, you can even archive the account holding it. Trading is not tied to your local trader account, you can send and receive via local trader using whichever account you have selected in your accounts tab at the time you trade. The local trader key is only used and needed to identify you against our servers and encrypt your private data.

As for the HD accounts: You will not get a new receiving address every time you show the address, but every time you actually receive funds. This is to prevent big gaps of unused addresses, which could cause problems upon later import. We will, however, in the future probably provide the ability to create multiple receiving addresses in an account in advance.

[trasla]

Synchronising definitely takes noticeably longer "all the time" with the new release for me.

How long doe sit approx take?
Do you have a very big amount of accounts and large number of keys in accounts?
We tested with accounts which had hundreds of keys and transactions.

What can really take some time is monitoring an address with very large numbers of unspent outputs.
Usually, an address just has few unspent outputs, but if you for example monitor some crowd-funding or donation address, which has hundreds or thousands of unspent outputs, it takes some time, since we verify all parent transactions for those in the app to make sure our servers can not trick our users.

[trasla]

Short update:
Version 2.02 re-introduces the old way to back up single keys, as per frequent demands.
Its within the settings, at the very bottom, and does only show if there actually is at least one single private key in the wallet.
Note that this does not back up the master seed and is by no means a substitution for making a proper wordlist backup.
We still advice people to move funds to hd accounts.

[Newar]

Synchronising definitely takes noticeably longer "all the time" with the new release for me.

How long doe sit approx take?
Do you have a very big amount of accounts and large number of keys in accounts?
We tested with accounts which had hundreds of keys and transactions.

What can really take some time is monitoring an address with very large numbers of unspent outputs.
Usually, an address just has few unspent outputs, but if you for example monitor some crowd-funding or donation address, which has hundreds or thousands of unspent outputs, it takes some time, since we verify all parent transactions for those in the app to make sure our servers can not trick our users.

17 seconds on the initial start from the home screen, 10 seconds when the black screen was on, but the app was "open" behind it. Previously it was maybe 2 or 3 seconds.

I don't think I have anything spectacular. 7 Keys in the new HD account and a single address from before, but that one has the few outputs it ever had completely spent.

Samsung GT-I9082 Android 4.2.2

[hgmichna]

You cannot migrate a local trader identity to another key.
This is due to the fact that your local trader chats are encrypted based on that key.
You can create a new identity based on an HD account.
But there is no downside to just keeping your local trader key and identity, you can even archive the account holding it. Trading is not tied to your local trader account, you can send and receive via local trader using whichever account you have selected in your accounts tab at the time you trade. The local trader key is only used and needed to identify you against our servers and encrypt your private data. …

Thanks, Newar and trasla, for the good information. All clear now.

Keeping the old Local Trader non-HD account is just a tad unpleasant, as it requires an old-style backup in addition to the HD backup, and that is just what we wanted to get rid of. But I see the point—there is no other good way. Local Trader migration would probably require an unreasonably high programming effort, not worth the trouble.

Perhaps a way could be devised to delete a Local Trader account completely, allowing to keep only the name or allowing to create a new Local Trader account with the same name, so the trader is still recognized by peers. That does not sound overly difficult. Anyway, no big deal.

[trasla]

Yes, deleting local trader accounts is on our list!

[Mitchell]

Is there anyway to export a private key of an address with the HD wallet? I cannot find it and it bothers me quite a lot. Sometimes I need an address on my phone somewhere else as well.

[trasla]

Is there anyway to export a private key of an address with the HD wallet? I cannot find it and it bothers me quite a lot. Sometimes I need an address on my phone somewhere else as well.

You can export the private keys of single address accounts by selecting them and then choosing export from the menu. You cannot do this with HD accounts, they hold a lot keys. What's your use case here?

[birr]

If you want to enter your own word list, you need to choose import backup on a fresh import (after wiping app data - make sure to backup the seed you currently use).

How do you wipe app data, do you mean uninstall it?
I have the HD wordlist generated by mycelium, only because the update to hd didn't give me the option of inputting my own.  But that's not how I would have done it given a choice.  So I would like to know how to wipe it and enter my own wordlist.

[trasla]

If you want to enter your own word list, you need to choose import backup on a fresh import (after wiping app data - make sure to backup the seed you currently use).

How do you wipe app data, do you mean uninstall it?
I have the HD wordlist generated by mycelium, only because the update to hd didn't give me the option of inputting my own.  But that's not how I would have done it given a choice.  So I would like to know how to wipe it and enter my own wordlist.

Uninstalling also wipes the data, but in the app management you usually get an option to just wipe data without uninstalling. Make sure to have backed up everything.
When you then start the app, choose import backup.

We don't give a choice on upgrade cause we feel it's a bad idea to use an own word list. We advise you to not use the same seed in two devices. And we strongly recommend not trying to pick ones own words. Humans are absolutely terrible at providing randomness with their brain. (also, the last word is a checksum - so picking own words is not that easy)

[KLmoney]

Just got around to organizing my Mycelium 2.0. Thanks for a great HD wallet app. I am looking forward to “growing” with this wallet as the Mycelium team continue to add features as I’m sure they will going by their track record.

BTW, Item 3 in the online Help needs editing now that single address accounts can be backed up. It would be nice if transaction and Account labels could also be backed up.

[GIANNAT]

Once I verified the seed with the future provided am I 100% sure that I can restore all of my address with that seed? Is there any way I can double check the seed? (I'm being a little paranoid an it's my first "swim" in the HD wallet)