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1  Bitcoin / Technical Support / Re: Best way to keep my Bitcoins safe? on: March 31, 2014, 05:10:44 AM
One thing I've done is move a small amount of bitcoin to my new offline wallets and wait a month. This is a honeypot and if anyone has somehow compromised my wallet generation process they would be tempted to drain the wallets.

After a while, with my wallets securely offline the whole time, if no one has touched my wallets I move the bulk of what I want to store to them.

Just another take on the process.
2  Bitcoin / Alternative clients / Re: Mycelium Bitcoin Wallet on: March 27, 2014, 04:31:16 PM
My question is, if I ever lose my phone, it's stolen, or anything else happens where I need to use the backup PDF document I created in a fresh installation of Mycelium, will the restore procedure always restore the most current amount of bitcoin associated with that address, or is the backup a snapshot of whatever the balance is when the backup is made?

You only need to backup once. Restoring to a new phone with a new install of Mycelium will show the full _current_ balance of your coins. (It goes to the p-p ledger/blockchain to look up your balance.)
3  Economy / Service Announcements / Re: [ANN] bitaddress.org Safe JavaScript Bitcoin address/private key on: March 09, 2014, 04:50:33 PM
Could you possibly make a wallet using a deck of cards? There are an insane amount of combinations possible, and you could at least just make a brainwallet by putting in the cards in order. Then you can just keep the deck in that order to save it.

Yes. Just shuffle a deck well and deal a few cards then enter them, using a code for each card, as the password in a brain wallet generator. Something like 1H for ace of hearts and KS for king of spades.

You need to pick the entropy you want, which will give you how many cards are needed in the deal. The whole deck gives you 52! combinations or 226 bits of entropy. You probably don't need much more than 100 bits though - so, fewer cards.

Number   Bits of
of cards   Entropy
15               82
16               87
17               93
18               98
19               103
20               108
21               113
22               118
23               123
24               128
25               132

4  Bitcoin / Alternative clients / Re: Mycelium Bitcoin Wallet on: March 09, 2014, 04:17:49 PM
Thanks for the clarification. Much appreciated!
5  Bitcoin / Alternative clients / Re: Mycelium Bitcoin Wallet on: March 08, 2014, 09:08:16 PM
I've run into a situation where Mycelium was monitoring two public keys - one the compressed version of the other. It showed a positive balance for the the compressed public key and a zero balance for the normal public key.

I loaded the private key to see if it was required for Mycelium to recognize that the two public keys are for the same private key, but it simply attached it to the compressed public key. The uncompressed one remained observer only (no private key associated) and still with a zero balance.

Questions:
- Is it mathematically possible to calculate the compressed public key from the uncompressed one (and visa-versa) in the absence of the private key? (I assume if you have the private key they can theoretically be associated since you can calculate each from the private key.)

- Is it possible to make one of the two forms the canonical form internally so that loading either into Mycelium causes the correct private key's balance to be tracked?


Background: I ended up with a compressed version of the public key when I loaded a BIP38 protected key into the app on a dedicated device separate from my phone. I then transferred some coin to it.
I had been monitoring the full public key on my regular phone and it failed to show the new balance. I then loaded the compressed key to my phone and ended up with the situation described.
6  Bitcoin / Bitcoin Discussion / Re: Client-Side Scrypt Based Brain Wallet Generator BIP38 Protected on: March 08, 2014, 08:26:33 PM
Also, added a button to let you select whether to display the full or compressed version of the Bitcoin Address when generating a BIP38 key.
7  Other / Beginners & Help / Re: Offline Cold Wallet on: March 08, 2014, 06:49:48 AM
You could roll one yourself.
Download the Bitaddress web page to your local machine and have it generate a cold storage wallet for you.

Also, see
I modified the Bitaddress Bitcoin Wallet Generator to allow the generation of Scrypt driven brain wallets that are BIP38 protected.

           http://goo.gl/ELvg7S

I modified the original brain wallet tab to use Scrypt and made it easy to copy the resulting Private Key to the BIP38 tab to protect it with a password.  (Incidentally, I also tore out some things I didn't want and changed the randomness pool mixer to make it more thorough.)

The usual caveats about never ever using brain wallets with less than 70 bits of entropy applies. Don't play with fire if you don't know how to estimate the entropy of the passphrase you use!
Download it to your machine, examine the code, run it offline and print your BIP38 protected cold wallets.

I use paper wallets with the Mycelium android client, which can decode BIP38 wallets and spend from cold storage. Mycelium is really nice about destroying the private key after spending from cold storage. Also, I can now keep the paper wallets in my pocket without worrying about losing them since they're encrypted.
8  Bitcoin / Bitcoin Discussion / Client-Side Scrypt Based Brain Wallet Generator BIP38 Protected on: March 08, 2014, 06:35:46 AM
I modified the Bitaddress Bitcoin Wallet Generator to allow the generation of Scrypt driven brain wallets that are BIP38 protected.

           http://goo.gl/ELvg7S

I modified the original brain wallet tab to use Scrypt and made it easy to copy the resulting Private Key to the BIP38 tab to protect it with a password.  (Incidentally, I also tore out some things I didn't want and changed the randomness pool mixer to make it more thorough.)

The usual caveats about never ever using brain wallets with less than 70 bits of entropy applies. Don't play with fire if you don't know how to estimate the entropy of the passphrase you use!
Download it to your machine, examine the code, run it offline and print your BIP38 protected cold wallets.

I use paper wallets with the Mycelium android client, which can decode BIP38 wallets and spend from cold storage. Mycelium is really nice about destroying the private key after spending from cold storage. Also, I can now keep the paper wallets in my pocket without worrying about losing them since they're encrypted.
9  Bitcoin / Alternative clients / Re: Mycelium Bitcoin Wallet on: March 02, 2014, 08:31:33 PM
at worst can break and make your wallet stop working

Well, to play devil's advocate, at WORST it can be maliciously made to misreport balances.  That's where the trust comes in, that the blockchain reporting to mycelium is the same blockchain everyone else is working with.



Yes of course, but in the same breath you should mention that the moment you suspect something you can check your public keys on https://blockchain.info and get a correct balance from them. In no way can the Mycelium server modify your balance on the block chain.

The real trust is that the code on your phone is honest since that holds your private keys and momentarily sees your paper wallet keys. That, however is verifiable since the code is published.
10  Bitcoin / Alternative clients / Re: Mycelium Bitcoin Wallet on: January 16, 2014, 05:05:58 AM
Hi

Need help please

I just flashed my phone and installing mycelium. I have the private key but unfortunately I lost my pass protected private key.
Is there any way to have access again to this address?
The problem is I just funded this address and need to pay something using this address.
Any help is appreciated


Best Regards

Do you mean you just have the public key?

If you have the private key it should load into your wallet normally, and you can then spend. If all you have is the public key then stop funding it. You cannot recover the private key from the public key.
11  Bitcoin / Alternative clients / Re: Mycelium Bitcoin Wallet on: January 14, 2014, 08:42:36 PM
Just want to say I love your apps making cold wallet spending super easy. =)

This wallet has a centralized API that goes against what bitcoin stands for. If a million people were doing some serious business with the wallet and someone wanted tos crew them over they coudl attack the server and poof your wallet doesn't work.

Hence your wallet's fate is always in the hands of a centralized person(s)... and you will always get this what happened in this post: https://bitcointalk.org/index.php?topic=293472.msg4473315#msg4473315

I tried to contact these people so I can make another "super node" using Devcoin but to no avail. I liked the interface and ported it over to Devcoin only to learn that all communications are happening via  a central API that this company has control over (so its not really open source after all), alas I moved onto using bitcoinj which is totally decentralized and doesn't have a big problem with downloading block data since it is using checkpoints and only downloading last 5 weeks of data.

You would simply backup your wallet and if you re-install a new version of the wallet you can import your keys again later. The whole "not having to download the blockchain" is actually a bad thing not a good one.

So your claim of open source does not stand, unless you open up the source to your API which I can then use to port my application.

The claim here: https://bitcointalk.org/index.php?topic=293472.msg3160266#msg3160266 as to why SPV store's are not good because you can't import arbritraty private keys without redownloading the entire blockchain from the genesis block node is a mute point and doesn't defeat the notion of SPV store being better than this proprietary private API. When someone wants to use the android wallet they simply transfer coins over to it without importing your QT wallet private key. Infact it is dangerous to even dump your private key so to encourage this behaviour is bad anyways.

The bitcoinj wallet will allow you to create a new key where you would send coins from your other wallet(s) to it and then you go from there. The SPV store will remember all transactions related to its own wallet from the time you installed the application. If you reinstall the application it will redownload from the last checkpoint which is the earliest time that you could have sent any coins for the wallet to care anyways.

Even if we update the checkpoints so the user would only ever have to download 5 weeks of data, by importing an older key from an older bitcoinj install, I believe since the hash of the blocks are saved relating to the transactions which the wallet would care about it would reimport these blocks when you import your old wallet.

Still, it does make cold wallet spending super easy.
12  Bitcoin / Development & Technical Discussion / Re: Alternative payment scheme on: January 05, 2014, 06:49:34 AM
Its a really thin abstraction layer and doesn't require any protocol changes

It does require the payee to publish his full public key. That is not common practice today. Bitcoin receive addresses are hashes of public keys and can't be used to derive related keys.

Nice idea, though. See this related topic:

This added note is to show how Alice allows a server fronting her business to verify that she owns a blinded transaction without requiring the server to have her secret key thus protecting her wallet if the server is hacked.

It’s done this way:

Alice generates a secondary key used to verify blinded transactions from her master key. Her private key is “a”. She generates a verifier private part “b” by hashing “a”,  b = Hash(a). Let the public part of “a” be “A” and the public part of “b” be “B”.   A = aQ and B = bQ. The doublet “A,B” is published as the blind transaction enabling public key. “A,B” and the private verifier “b” are given to the server she is using to manage monitoring the block chain for her. With “b” the server can verify transaction ownership but not spend. Hacking the server does not give you “a”.

A sender would recognize “A,B” as a blindable key. The sender then generates "X" as follows:  s = Hash(m,yB);  X = sA. The sender sends coin to “X”.

A server holding verifier "b" can check every new transaction for the property that s = Hash(m,bY) and X = sA to know to add the coins to the balance in Alice’s wallet. (Note yB = bY). Notice that the server does not need “a” to verify the transaction. The server can verify “X” but cannot generate the private part of “X”.

Alice later generates "x", the private part of "X", as follows:  She is given m and Y from the transaction; then  s = Hash(m,bY);  x = sa (modulo a large prime determined by the ECC);  She can check that X = xQ. Alice can now sign a prepared transaction using “x” and publish the signed transaction when spending.
13  Economy / Speculation / Re: My last prediction of the year! This is a good one, I promise! on: December 30, 2013, 09:31:24 PM
mining becomes less and less relevant as bitcoin grows

Sorry if I have misunderstood something but mining is actually necessary to keep the blockchain updated with payments. It is therefore important to factor this into the argument for the future. When Bitcoin takes off as a payments system (both Bitcoin transactions and Fiat > Bitcoin > Fiat [think Bitpay] transactions) then miners are powering the engine that keeps this system going. It will be necessary that they remain profitable in order that they stay in business to power the system - the price of Bitcoins must be satisfactory to the miners - but you should also remember that they will take a share of transaction fees within the system, which should count for more, a lot more, in the future.

No one is guaranteeing miners anything, least of all profitability. If they are necessary and useful, transaction fees will go up to replace the reward Bitcoins lost per block. Note this requires that users must feel _some_ pain if they want timely transactions.
14  Bitcoin / Alternative clients / Re: BitcoinSpinner on: December 19, 2013, 02:37:23 AM
The App is dead....    Long live the App

Goodbye to a great Bitcoin wallet. Well done Jan.
15  Bitcoin / Bitcoin Discussion / Re: Best Bitcoin Android apps and widgets on: December 12, 2013, 11:18:07 PM
ZeroBlock


the fact that you missed this is quite sad.

best app ever.

I think so, this is hands down the best app for iphone and soon to be the best for android (once some additional features are added). Time to update the list.

Does it hold the secret keys in the app or are they held by the ZeroBlock servers? Does any one know?
16  Bitcoin / Bitcoin Discussion / Re: Best Bitcoin Android apps and widgets on: December 11, 2013, 05:53:19 AM
How about Mycelium? https://play.google.com/store/apps/details?id=com.mycelium.wallet&hl=en

Hands down the best wallet, IMHO!! Love the cold storage feature, and the ability to do partial spends of paper wallets!

Yes!
17  Bitcoin / Development & Technical Discussion / Re: New paper: Accelerating Bitcoin's Trasaction Processing on: December 07, 2013, 06:00:59 AM
... it's really hard for two people (or more) who want to make a transaction to find a blockchain that they have in common where the transaction can be made.  You have to have both of them going up the tree to the lowest tree node that they have in common, which would concentrate fully a quarter of the traffic on the root blockchain, split another quarter between its two subchains, split an eighth of the traffic between their four second-level subnchains, etc.  That won't scale past about four times what Bitcoin can handle now, because the root blockchain of the tree scheme would become a bottleneck.

This assumes no locality to the transactions. If transactions aggregate (by geography for example or by business type) then people will often find blockchains in common near the leaves without needing to go to the root (less often than the 25% of the time you indicate one hopes.)

Very interesting. Reminds me of banks and clearing transactions between banks within a country vs. transactions that require a transfer between banks in different countries.
18  Bitcoin / Alternative clients / Re: Mycelium Bitcoin Wallet on: December 06, 2013, 10:04:23 PM
BIP38 works perfectly on my DROID BIONIC (Android 4.1.2) taking less than a minute.
Works as well on an older HTC INCREDIBLE (Android 2.3.4) taking about 3 minutes.
The BIP38 is compatible with BitAddress generated BIP38 keys. Does Mycelium generate BIP38 protected exports?

Thanks again for a great wallet.

19  Bitcoin / Alternative clients / Re: Mycelium Bitcoin Wallet on: November 23, 2013, 07:57:08 PM
New version (1.0.5 I think) works perfectly on my DROID BIONIC (Android 4.1.2) and on an older HTC INCREDIBLE (Android 2.3.4)

Nice work. I like the new backup scheme.

One request - a Cold Store capability using an encrypted private key. (Maybe the plan is this will come with BIP38, but if that takes a long time to load on a phone maybe a version with a faster set of SCRYPT parameters could be considered?)

The format used by the encrypted PDF backup already works with the Cold Storage Spending feature.  Smiley


Oh. I hadn't tried it. I hate carrying the password in my pocked with the encrypted key but I guess I could write down 10 of the characters of the password and memorize five of them.

Thanks Jan.
20  Bitcoin / Alternative clients / Re: Mycelium Bitcoin Wallet on: November 23, 2013, 08:45:47 AM
New version (1.0.5 I think) works perfectly on my DROID BIONIC (Android 4.1.2) and on an older HTC INCREDIBLE (Android 2.3.4)

Nice work. I like the new backup scheme.

One request - a Cold Store capability using an encrypted private key. (Maybe the plan is this will come with BIP38, but if that takes a long time to load on a phone maybe a version with a faster set of SCRYPT parameters could be considered?)
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