Payment using both tumbled and un-tumbled coins?

[sol_bit]

Hi guys, I'm new to bitcoin and would just like some info on tumbling.

Say I've bought bitcoins on an exchange and transferred them to one of the addresses in my Electrum wallet. I then tumble those coins and have them returned to a new address in my wallet. Now say I realise that I actually need more bitcoin for a purchase. So I buy more and have them sent to another address in my wallet.

If I now want to use all the coins for a private purchase would it then be necessary to send ALL of the bitcoin into the tumbler (including those which have already been tumbled). This is of course assuming I want to be secure and do not want the coins linked back to me.

Any help will be appreciated!

[shorena]

What is your "attack scenario" or in other words what are you trying to defend against?

[achow101]

It would not be necessary to send all of the coins through the mixer, just the ones that you bought. Only those new ones are linked to your identity. After mixing them, then they would not be linked to you. However, this also means that the two addresses will be linked to each other, but they won't be linked back to you so it is ok.

[shorena]

It would not be necessary to send all of the coins through the mixer, just the ones that you bought. Only those new ones are linked to your identity. After mixing them, then they would not be linked to you. However, this also means that the two addresses will be linked to each other, but they won't be linked back to you so it is ok.

I thought of this, but I'm not sure how to send only the new (unmixed) coins? From what I can see (I'm using Electrum), I can't specify that when sending. Or would sending the exact amount of bitcoin that I bought use all of those coins which are still linked to me?

Thats correct. Electrum does not allow you to select which inputs[1] you use. The idea is that you mix or tumble all bitcoins that go into your electrum wallet and thus it does not matter if they are connected towards eachother as no address from your electrum wallet is connected to you as a person. Keep in mind that electrum servers can connect the addresses to your IP address if you dont use tor or an anonymous VPN.

[1] formerly received bitcoin

[unholycactus]

If you wish to have better privacy, you should use another wallet service.
Shorena clearly mentioned why (input selection and access to your IP).

A wallet like Armory should do the trick, although it requires you to download the whole blockchain.

[shorena]

If you wish to have better privacy, you should use another wallet service.
Shorena clearly mentioned why (input selection and access to your IP).

A wallet like Armory should do the trick, although it requires you to download the whole blockchain.

Electrum is fine for this case. They dont have to worry about connecting bitcoin addresses if all coins that come in have no connection to the exchange and the real IP can not be connected to the wallet.

To give a generic example: It would be an issue for someone that scammed bitcoin on a certain address and wants to try again or hide their tracks. Connected addresses are a common way to proof someone with an alt account scammed in the past. Thats why I asked what this is about. You can always go all out and run your own full node over tor, mix all TX etc, but for most people a few things are enough to achieve their goal. This is also allows options e.g. OP could also use Mycelium or most other wallets (and even some services) over Tor.

[odolvlobo]

In order to prevent all possibility of tracking your bitcoin addresses, you must mix bitcoins both entering and leaving the wallet.

If you don't mix bitcoins leaving the wallet, then your addresses and all your spending can potentially be tracked by anyone that you send bitcoins to.

If you don't mix bitcoins entering your wallet, then your addresses and all your income can potentially be tracked by anyone that sends you bitcoins.

Something else to consider: the mixer can track everything.

[shorena]

In order to prevent all possibility of tracking your bitcoin addresses, you must mix bitcoins both entering and leaving the wallet.

If you mix only bitcoins entering the wallet, then your addresses and all your spending can be tracked by anyone that you send bitcoins to.

If you mix only bitcoins leaving your wallet, then your addresses and all your income can be tracked by anyone that sends you bitcoins.

Something else you need to consider: the mixer can track everything.

This is an important issue, thanks for bringing that up. Mixers should be switched from time to time. It might be even a good idea to use high volume services as mixers, e.g. old long running casinos or exchanges. You can also go the extra mile and use an exchange that also trades in alts and switch currencies for mixing sake.

[Hallmader]

This is an important issue, thanks for bringing that up. Mixers should be switched from time to time. It might be even a good idea to use high volume services as mixers, e.g. old long running casinos or exchanges. You can also go the extra mile and use an exchange that also trades in alts and switch currencies for mixing sake.

Do you mean I can transfer bitcoin to one exchange and buy altcoin, then move the altcoin to another exchange, then sell the altcoin to buy bitcoin?

[shorena]

This is an important issue, thanks for bringing that up. Mixers should be switched from time to time. It might be even a good idea to use high volume services as mixers, e.g. old long running casinos or exchanges. You can also go the extra mile and use an exchange that also trades in alts and switch currencies for mixing sake.

Do you mean I can transfer bitcoin to one exchange and buy altcoin, then move the altcoin to another exchange, then sell the altcoin to buy bitcoin?

Yes, for best results use an alt that was created for privacy and has the needed volume on both exchanges. This would require a bit of research first - volume and features of the various alt coins - but it should result in very well mixed coins that are very difficult to track.

The way I can imagine someone being able to track this would be if they had compromised both exchanges, your method of masking your IP when you connect to them (e.g. Tor or a VPN) and(!) the alt does a poor job in hiding the origin and/or destiny of the transaction. If the exchanges lack volume it does not matter how good the alt coin is. If you are the only buying and selling 1 BTC while you only see 0.01 btc on a normal day, its pretty easy to draw a connection. If you are way over the volume you will also move the price of the coin around which would make this an expensive mix.

Disclaimer: Im theory crafting here, there might be gaping holes in this idea that I did not think about.

[Hallmader]

This is an important issue, thanks for bringing that up. Mixers should be switched from time to time. It might be even a good idea to use high volume services as mixers, e.g. old long running casinos or exchanges. You can also go the extra mile and use an exchange that also trades in alts and switch currencies for mixing sake.

Do you mean I can transfer bitcoin to one exchange and buy altcoin, then move the altcoin to another exchange, then sell the altcoin to buy bitcoin?

Yes, for best results use an alt that was created for privacy and has the needed volume on both exchanges. This would require a bit of research first - volume and features of the various alt coins - but it should result in very well mixed coins that are very difficult to track.

The way I can imagine someone being able to track this would be if they had compromised both exchanges, your method of masking your IP when you connect to them (e.g. Tor or a VPN) and(!) the alt does a poor job in hiding the origin and/or destiny of the transaction. If the exchanges lack volume it does not matter how good the alt coin is. If you are the only buying and selling 1 BTC while you only see 0.01 btc on a normal day, its pretty easy to draw a connection. If you are way over the volume you will also move the price of the coin around which would make this an expensive mix.

Disclaimer: Im theory crafting here, there might be gaping holes in this idea that I did not think about.

I know two anonymous coins, Dash and Monero. Will either of those do the trick you mentioned.