Topic: Blockchain.info - Bitcoin Block explorer & Currency Statistics - page 36. (Read 482544 times)

Cool. Thanks for going forward on this.

Do I understand correctly that the pool server still knows which inputs and outputs were provided by who? So you still trust the server regarding privacy, just not coins, right?

As the transactions are large and incur high network fees, paid by the operator, there is an advantage to the operator to have multiple participants in one transaction.

But for users themselves as long as the coins in the sharedcoin wallet are being consistently swapped with fresh coins (tainted by many sources) it doesn't necessarily matter if another user is directly involved in your transaction or not. In fact the server can provide better anonymity (see below).


Only if you are mixing with other users who want to send different amounts. When mixing with the sharedcoin pool the server doesn't desire any particular output size so can deliberately add input and output combinations which mimic your own. Then when you include randomised fees into the mix it makes it almost impossible to determine the inputs used from the value of one output.


Yes there will be a browser extension available which you can input a private key.

Cool! Does it allow other users not using blockchain.info to join a coinjoin transaction?

Is it important to use whole increments (like 0.1 BTC) when using this? If so, you should enforce that in the user interface.
(if you can send arbitrary amounts, that's cool, I don't know how this works)

Well duh, blockchain.info has no control whatsoever over what rate you're exchanging at with whatever exchange counterparty you agreed of your own free will.  So if blockchain were to claim you'd get 10 EUR and you got 9, I guess you'd blame them for that too?

Hopefully you can see the problem in your suggestion.  The best that could be done is that blockchain say the rate is indicative.  You should expect an indicative rate to be 5% or more wrong worst case.  Are you happy?  If so, you understand.  If not happy, you need to think more.

This would be really great, the feature of picking your price in your home currency is great, but unless you can chose which exchange to trust for the price, it isn't really useful.

Does this imply that you only "mix" your coin with people also trying to mix them in those 40 seconds?
i.e. it works much better within peak activity?

Sharedcoin trustless mixing now available for testing

Sharedcoin uses a technique known as coinjoin to provide coin mixing without needing to trust any third party with your funds. The service still relies on a centralised server but that server only co-ordinates transactions without any funds passing through it. The main advantages are significantly less risk for both the user and operator and no requirement to keep any logs.

Anyone interested in testing can login using the following link:

https://blockchain.info/wallet/login?enable_sharedcoin=true

Please test with small amounts only (0.5 BTC max). 0.1 BTC is the minimum send amount. If you experience any errors please record the output from the javascript console.

The current client stages are:

- The client will submit its "offer", which is the inputs it wants mixing and the desired outputs.
- The server waits a certain amount of time for other clients to submit their offers.
- The server combines everyone's offers and creates a "proposal".
- The clients check they are happy with the proposal and signs their inputs.
- The server submits the final transaction.

The entire process takes about 40 seconds.

Features currently supported:

- Variable number of inputs and outputs per client
- Variable input and output values.
- Randomised fees.
- Ability to draw upon reserve funds when no other participants are available for mixing.
- Taint analysis determines the appropriate inputs to mix.

Features planned:

- Multiple iterations using temporary addresses never saved inside wallets.
- Better randomisation of change outputs and splitting of outputs between multiple iterations.
- Better progress indication.
- Documented Client APIs and SDK.

Example sharedcoin transaction:
 https://blockchain.info/tx/72316782bf48d0cd232b888a7b9ea03f88ba79fac28273cd2aa1804683235412?show_adv=true

The amount currently available in the reserve pool is low, this will be gradually increased over time but during the testing phase if anyone manages to manipulate the client to withdraw excess funds from the pool they can keep that amount.

Client source available at: https://github.com/blockchain/My-Wallet/blob/master/sharedcoin.js
Server status can be viewed while testing at: https://api.sharedcoin.com/

Great work piuk, keep it up 

This should be fixed now.


This will be available next update. Btw you should get a warning if trying to send with a fee above 1 BTC, perhaps the warning should be lowered to 0.1 BTC.


Will be fixed next update as well.


I'm having trouble getting it re-approved into the extension store. For now it can be downloaded directly from here https://github.com/blockchain/My-Wallet-Firefox-Extension/raw/master/blockchain.xpi.


The electricity cost on the existing chart could either be changed a certain date when the first ASICs became available (1st Feb 2013?) or a new chart started for only ASICs . Not sure which would be better.


It is only set on wallet pages e.g. https://blockchain.info/wallet


The out of date iPhone app doesn't support compressed public keys which is preventing them from being made default. When the app is finally updated  this can change.

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Update for the Mac OSX client available in the app store https://itunes.apple.com/gb/app/blockchain/id688882038?mt=12

I totally agree they should do compressed keys, but for those of you that want to use them now, you can import private keys made from other clients, so you can make a compressed key with another client then import it into blockchain.info. And no I'm not saying they shouldn't add the ability to create them, but you can technically do it now with some hassle.

You can tell if a key is compressed if it starts with an L or a K. Uncompressed keys start with a 5.

I'm keeping track of all these suggestions, because we're constantly trying to improve the site. Thanks so much for the feedback so far!

You could even get fancy and give us the option to pick our exchange (for price) and give the option to enter a % premium or % discount.

This!

Feature suggestion - using compressed public keys by default

As far as I was able to check, the blockchain wallet uses uncompressed public keys by default. Since it is very popular, a lot of people are using uncompressed keys. If you were to switch over to compressed public keys, each transaction sent from the wallets using those keys would be smaller, meaning the future blocks could accommodate more transactions. Just a way to be forward thinking and "greener" .

More info on compressed public key - http://bitcoin.stackexchange.com/questions/3059/what-is-a-compressed-bitcoin-key .

I've been using this site for about a year.
Works great  when you don't want to set up a client (and download the whole chain ).

Yeah it definitely doesn't log off after inactivity.
Also, after typing in the secondary password to make a transaction, it will never prompt again till next session.
Because of these two factors, a user's chrome app wallet left minimized and computer left unattended, all coins can be subject to theft.

IMO, the secondary password should function like a PIN, and needs to be entered for each transaction.   The secondary password should only expose the private keys to the system just for signing the transaction.

Yes, please print a text version of the key, it would be very convenient for users with older phones for which there are alternative Gauth implementations but none of them can scan QR codes. Other QR scanning apps are also problematic to work with.

App manager says 3.6 - Play Store website says that's the latest version too. Here's how I get to it: Open app, choose a transaction to open "Transaction Summary" popup, press the underlined Hash value to open the link. I'm opening the link in the default Internet app (Android 4.1.2) which throws me to Google as the URL isn't recognised. Maybe other apps auto-convert https:/ into https:// ?


Great - good to know there's a workaround in the meantime. Cheers.

I'll add these to the suggestion box.


I'm checking into why this isn't on the Firefox app page. If what you are reporting about 1.98 was widespread, then it may have been removed until this can be resolved.

Thanks for adding, it was working fine but it seems that there is not working right now.

Inspecting with http://web-sniffer.net/ you can see that no "strict-transport-security:" is set when you type https://blockchain.info.