Why Bitcoin needs block filters

[Kruw]

A shocking amount of Bitcoin wallets are built such that they forfeit your privacy at step 1 by sharing your addresses with third party servers.  No matter how carefully you label your UTXOs and track your spending, common ownership clusters are revealed simply from the synchronization process.  This article covers the historical attempt to solve light wallet privacy (BIP37 bloom filters) that failed, and the prevailing solution (BIP157/158 compact block filters) for those who have hardware or bandwidth limitations that exclude usage of a full node: https://bitcoinmagazine.com/technical/why-bitcoin-wallets-need-block-filters

Combining compact block filtering with Tor and selectively disconnecting from peers after block download requests prevents any efforts to recombine this data into a traceable wallet history.

[DaveF]

I might get jumped on for this but I really see it as an answer in search of a question.

1st you need people who care about privacy, and as we see time and time again, it's a small, but very vocal segment of the BTC community. If you really want privacy for your crypto transactions then use one of the privacy alts.

2nd you need a bit more powerful HW and more bandwidth with BIP 157/158 then with a regular non private SPV wallet. Nor a big deal, but still worth a mention.

3rd Just on a personal level I am getting REALLY tired with the perpetual it's too expensive to run a node BS. Yes in many parts of the world $125 is more money then a lot of people will ever be able to spend on one.
These are not the people who care about privacy. For the most part, they want to quickest and simplest way to get a TX done. Privacy is way down on the list.

-Dave

[franky1]

heres a shower thought for you

because light wallets dont do all full node processes like for instance relay random peoples transactions around the network. they only broadcast transactions made by the wallet.

so each time you make a transaction.. the intercepting peer will know your utxo when you send out a tx.

so they will know about who has what addresses even with some utxoset/blockchain obfuscation request

enjoy that thought

[Kruw]

heres a shower thought for you

because light wallets dont do all full node processes like for instance relay random peoples transactions around the network. they only broadcast transactions made by the wallet.

so each time you make a transaction.. the intercepting peer will know your utxo when you send out a tx.

so they will know about who has what addresses even with some utxoset/blockchain obfuscation request

enjoy that thought

What do you mean by "the intercepting peer will know your UTXO when you send out a tx"? Did you mean they will know your IP address originated the transaction since you don't relay unowned transactions?

[franky1]

heres a shower thought for you

because light wallets dont do all full node processes like for instance relay random peoples transactions around the network. they only broadcast transactions made by the wallet.

so each time you make a transaction.. the intercepting peer will know your utxo when you send out a tx.

so they will know about who has what addresses even with some utxoset/blockchain obfuscation request

enjoy that thought

What do you mean by "the intercepting peer will know your UTXO when you send out a tx"? Did you mean they will know your IP address originated the transaction since you don't relay unowned transactions?

forfeit your privacy at step 1 by sharing your addresses with third party servers.

again if you are concerned with the "third party servers" (peers intercepting your data) they will learn what bitcoin addresses you control simply by waiting for you to spend your funds through their servers as they are the host server to your wallet app.

[Kruw]

heres a shower thought for you

because light wallets dont do all full node processes like for instance relay random peoples transactions around the network. they only broadcast transactions made by the wallet.

so each time you make a transaction.. the intercepting peer will know your utxo when you send out a tx.

so they will know about who has what addresses even with some utxoset/blockchain obfuscation request

enjoy that thought

What do you mean by "the intercepting peer will know your UTXO when you send out a tx"? Did you mean they will know your IP address originated the transaction since you don't relay unowned transactions?

forfeit your privacy at step 1 by sharing your addresses with third party servers.

again if you are concerned with the "third party servers" (peers intercepting your data) they will learn what bitcoin addresses you control simply by waiting for you to spend your funds through their servers as they are the host server to your wallet app.

You seem to misunderstand, BIP157/BIP158 supporting light clients do not share addresses with any third party servers.  They download blocks from the peer to peer network the same way full nodes do, the difference is that they don't download every block, just the ones they need (along with some false positives).

[franky1]

i do understand.. what you dont understand is you are narrowly thinking of the block-sync aspect.. i am talking about the later spending session
when you spend funds.. your wallet only sends out transactions made by YOU. so the only transactions a litewallet server host receives from you are your transactions you signed. meaning they can learn what bitcoin addresses you control via just waiting for you to spend funds, they then look at what the possible "change"(return remainder funds) address is, and other such things

[Kruw]

i do understand.. what you dont understand is you are narrowly thinking of the block-sync aspect.. i am talking about the later spending session
when you spend funds.. your wallet only sends out transactions made by YOU. so the only transactions a litewallet server host receives from you are your transactions you signed. meaning they can learn what bitcoin addresses you control via just waiting for you to spend funds, they then look at what the possible "change"(return remainder funds) address is, and other such things

Common input ownership and change is revealed when you spend coins using your full node too, what point are you trying to make exactly?

[franky1]

i do understand.. what you dont understand is you are narrowly thinking of the block-sync aspect.. i am talking about the later spending session
when you spend funds.. your wallet only sends out transactions made by YOU. so the only transactions a litewallet server host receives from you are your transactions you signed. meaning they can learn what bitcoin addresses you control via just waiting for you to spend funds, they then look at what the possible "change"(return remainder funds) address is, and other such things

Common input ownership and change is revealed when you spend coins using your full node too, what point are you trying to make exactly?

YOUR point is you think that syncing to a server via a lightwallet risks the server knowing your bitcoin addresses only via block-sync/utxoset.. where you think filters/random requests will give you privacy..
MY point is you are still not private because there are many other ways the server can learn of your addresses and i mentioned just one.. hint: there are many

extra point, light wallets are programmed to speak to specific servers and only send YOUR transactions to them.
full nodes send thousands of NOT-YOUR transactions every 10 minutes. thus peers wont know which one is yours. plus you can blacklist/disconnect peers and change your peers easily, thus not stuck to a certain monitoring peer all the time.. thus fullnodes are safer

[Kruw]

YOUR point is you think that syncing to a server via a lightwallet risks the server knowing your bitcoin addresses only via block-sync/utxoset.. where you think filters/random requests will give you privacy..
MY point is you are still not private because there are many other ways the server can learn of your addresses and i mentioned just one.. hint: there are many

extra point, light wallets are programmed to speak to specific servers and only send YOUR transactions to them.
full nodes send thousands of NOT-YOUR transactions every 10 minutes. thus peers wont know which one is yours. plus you can blacklist/disconnect peers and change your peers easily, thus not stuck to a certain monitoring peer all the time.. thus fullnodes are safer

You are still confused.  There is no "server" with BIP157/BIP158 light wallets and transactions are never sent anywhere.  BIP157/BIP158 filters are scanned locally to allow the wallet to distinguish which blocks to download (because they contain transactions to or from the wallet) and which blocks not to download (because they don't contain transactions to or from the wallet).

[franky1]

YOUR point is you think that syncing to a server via a lightwallet risks the server knowing your bitcoin addresses only via block-sync/utxoset.. where you think filters/random requests will give you privacy..
MY point is you are still not private because there are many other ways the server can learn of your addresses and i mentioned just one.. hint: there are many

extra point, light wallets are programmed to speak to specific servers and only send YOUR transactions to them.
full nodes send thousands of NOT-YOUR transactions every 10 minutes. thus peers wont know which one is yours. plus you can blacklist/disconnect peers and change your peers easily, thus not stuck to a certain monitoring peer all the time.. thus fullnodes are safer

You are still confused.  There is no "server" with BIP157/BIP158 light wallets and transactions are never sent anywhere.  BIP157/BIP158 filters are scanned locally to allow the wallet to distinguish which blocks to download (because they contain transactions to or from the wallet) and which blocks not to download (because they don't contain transactions to or from the wallet).

YOU were the one talking about all the wallets that dont use the bips, ill remind you

A shocking amount of Bitcoin wallets are built such that they forfeit your privacy at step 1 by sharing your addresses with third party servers.  

and i responded

the wallets which your first sentance of topic eludes to are the ones that would just send out a bitcoin address to a server/peer and in receipt grab utxo of the wallet keys.. which yes is privacy concern
for litewallets that do not download the entire blockchain(their main feature of being different to full nodes). if you were to send a request to any peer or server of 999 random addresses, the wallet cannot establish used random addresses to obfuscate away from the wallets true addresses.. thus any receiver of such request would get 999 addresses of empty unused addresses(because the wallet had to make them up) and then one valid used address which the peer or server would then know thats the significant/intended address trying to hide.

its the needle in haystack game in reverse.. say you have a needle but want to hide it. but you dont have access to the full utxoset to grab 999 other needles of other peoples funds to hide your needle. so you make up random 999 straws of unused addresses.. thus when parsing you the data peers see 999 hollow straws and one needle. they find the needle because its not a straw

..
the other thing was even without the address/utxo grabbing privacy leak whether via peers/servers... any intercepting node can just connect to you, knowing you are a litewallet that does not relay all pre-confirm payments of the network, but instead just your own. and just waits until you make a spend to know the addresses you have control over

there are many many many other ways to leak data whether a litewallet linked to a branded server of same brand as the wallet software.. or a litewallet that has some capability of random node connection

the thing is.. light wallets are light for a reason. they dont receive or send all blockchain data, nor all network transactions.. so by default of their feature of being light there are many ways connected peers can learn more about a litewallet user than a full node user.

litewallet users sacrifice privacy for convenience

[Kruw]

YOUR point is you think that syncing to a server via a lightwallet risks the server knowing your bitcoin addresses only via block-sync/utxoset.. where you think filters/random requests will give you privacy..
MY point is you are still not private because there are many other ways the server can learn of your addresses and i mentioned just one.. hint: there are many

extra point, light wallets are programmed to speak to specific servers and only send YOUR transactions to them.
full nodes send thousands of NOT-YOUR transactions every 10 minutes. thus peers wont know which one is yours. plus you can blacklist/disconnect peers and change your peers easily, thus not stuck to a certain monitoring peer all the time.. thus fullnodes are safer

You are still confused.  There is no "server" with BIP157/BIP158 light wallets and transactions are never sent anywhere.  BIP157/BIP158 filters are scanned locally to allow the wallet to distinguish which blocks to download (because they contain transactions to or from the wallet) and which blocks not to download (because they don't contain transactions to or from the wallet).

YOU were the one talking about all the wallets that dont use the bips, ill remind you

A shocking amount of Bitcoin wallets are built such that they forfeit your privacy at step 1 by sharing your addresses with third party servers.  

and i responded: even if you change those wallets to add in alot of noise data. of random other addresses. , problems still remain

the wallets which your first sentance of topic eludes to are the ones that would just send out a bitcoin address to a server/peer and in receipt grab utxo of the wallet keys.. which yes is privacy concern
for litewallets that do not download the entire blockchain(their main feature of being different to full nodes). if you were to send a request to any peer or server of 999 random addresses, the wallet cannot establish used random addresses to obfuscate away from the wallets true addresses.. thus any receiver of such request would get 999 addresses of empty unused addresses(because the wallet had to make them up) and then one valid used address which the peer or server would then know thats the significant/intended address trying to hide.

its the needle in haystack game in reverse.. say you have a needle but want to hide it. but you dont have access to the full utxoset to grab 999 other needles of other peoples funds to hide your needle. so you make up random 999 straws of unused addresses.. thus when parsing you the data peers see 999 hollow straws and one needle. they find the needle because its not a straw

..
the other thing was even without the address/utxo grabbing privacy leak whether via peers/servers... any intercepting node can just connect to you, knowing you are a litewallet that does not relay all pre-confirm payments of the network, but instead just your own. and just waits until you make a spend to know the addresses you have control over

there are many many many other ways to leak data whether a litewallet linked to a branded server of same brand as the wallet software.. or a litewallet that has some capability of random node connection

the thing is.. light wallets are light for a reason. they dont receive or send all blockchain data, nor all network transactions.. so by default of their feature of being light there are many ways connected peers can learn more about a litewallet user than a full node user.

litewallet users sacrifice privacy for convenience
becasue

You still don't understand.  Here's what your node sees when I use my BIP157/BIP158 light wallet:

Peer from random Tor IP connects
Peer requests a single block
Peer from random Tor IP disconnects

No addresses are shared.  No transactions are shared.  Can you explain to me how you can hurt my privacy from my wallet's syncing based on the behavior you observed using your node?

[franky1]

you start a topic about how risky NON bip 157 litewallets are

and while i state about them you cry, whinge moan about the privacy leaks at the block/utxo sync, you are ignoring there are other privacy leaks
it seems you are not thinking about privacy leaks but just trying to promote that you think bip157 is the be-all end-all solution to litewallet privacy leaks

you obsess about IP addresses yet the topic post was about bitcoin address associations
tor is tor so yes tor users dont have to think about IP issues. thus not part of the conversation..

but when it comes to details of what wallet has what keys. there are many many leakages of using a lite wallet. which 157 does not solve

so how about formulate your problem again. if its about bitcoin address associations.. talk about that
if its about privacy leaks of bitcoin address associations: dont just think about one narrow use case but realise litewallets have far more leaks

your meandering to now talk about IP addresses has nothing to do with the UTXO stuff you were talking in the topic post. so why keep thinking that people are not understanding it if they are not talking about IP addresses..

i am and was not talking about IP. neither was your topic post. so take the meander of IP out of the conversation and realise i and you were talking about privacy leakage of bitcoin address associations

there are many. realise that litewallets sacrifice privacy for convenience and even with the bips you mention a lite wallet still has many leaks

[Kruw]

you start a topic about how risky NON bip 157 litewallets are

and while i state about them you cry, whinge moan about the privacy leaks at the block/utxo sync, you are ignoring there are other privacy leaks
it seems you are not thinking about privacy leaks but just trying to promote that you think bip157 is the be-all end-all solution to litewallet privacy leaks

but when it comes to details of what wallet has what keys. there are many many leakages of using a lite wallet. which 157 does not solve

so how about formulate your problem again. if its about bitcoin address associations.. talk about that
if its about privacy leaks of bitcoin address associations: dont just think about one narrow use case but realise litewallets have far more leaks

there are many. realise that litewallets sacrifice privacy for convenience and even with the bips you mention a lite wallet still has many leaks

It is the be-all end-all solution for light wallet privacy.  BIP157 light wallets have the same privacy as full nodes since they download blocks instead of sharing addresses, and you have yet to prove otherwise. I'd suggest reading the BIPs, or at the very least, read the article mentioned in the OP:

https://bips.xyz/157
https://bips.xyz/158
https://bitcoinmagazine.com/technical/why-bitcoin-wallets-need-block-filters

[Kruw]

Visual explainer of block filters: https://www.youtube.com/watch?v=QCl7BIbjGc8

[Synchronice]

A shocking amount of Bitcoin wallets are built such that they forfeit your privacy at step 1 by sharing your addresses with third party servers.

I can't believe my eyes, is Kruw saying that? Kidding

3rd Just on a personal level I am getting REALLY tired with the perpetual it's too expensive to run a node BS. Yes in many parts of the world $125 is more money then a lot of people will ever be able to spend on one.

Yes, that's bullshit. No offence but if person doesn't have enough income to buy a basic computer, probably that person doesn't know about Bitcoin or doesn't have access to internet or won't be able to invest in bitcoin and it's probably out of that person's plans.

Many of you probably know that I love travelling and I love it especially in Eastern Europe. Even in many poor countries I have seen lots of people with iPhones while they were struggling to have a dinner in a restaurant. It all comes down to priorities.

[BlackHatCoiner]

I'm curious though, to which extent do they provide the same levels of privacy as with running a full node? I'm skeptic when it come to privacy-friendly lightweight solutions, privacy and convenience are usually sort of a tradeoff in my mind. Nonetheless, I have understood how compact block filters work, and it's pretty smart.

I'm just thinking, is it less effective the more the blocks the user requests?

[philipma1957]

I might get jumped on for this but I really see it as an answer in search of a question.

1st you need people who care about privacy, and as we see time and time again, it's a small, but very vocal segment of the BTC community. If you really want privacy for your crypto transactions then use one of the privacy alts.

2nd you need a bit more powerful HW and more bandwidth with BIP 157/158 then with a regular non private SPV wallet. Nor a big deal, but still worth a mention.

3rd Just on a personal level I am getting REALLY tired with the perpetual it's too expensive to run a node BS. Yes in many parts of the world $125 is more money then a lot of people will ever be able to spend on one.
These are not the people who care about privacy. For the most part, they want to quickest and simplest way to get a TX done. Privacy is way down on the list.

-Dave

See the reply above by davef . 

fuck btc privacy it does not exist.

Furthermore if you are for btc privacy you are against btc adaptation as the governments of the world are not going to want that.

If you want to be sneaky the alt  m....o is what you need.

As for running full nodes.

it is cheap to run one. I did a thread on a linux laptop  my cost was zero an office was tossing it. I put in a 2tb ssd ($85) I downloaded the whole chain in about 16 hours. This should be good for around 3-5 years.

[Kruw]

I'm curious though, to which extent do they provide the same levels of privacy as with running a full node? I'm skeptic when it come to privacy-friendly lightweight solutions, privacy and convenience are usually sort of a tradeoff in my mind. Nonetheless, I have understood how compact block filters work, and it's pretty smart.

I'm just thinking, is it less effective the more the blocks the user requests?

It's more effective if the user requests more blocks, hence, a full node that downloads every block has zero chance of revealing anything by omission.  The false positive block downloads from filters contribute to privacy in this way since a peer cannot know for certain that a block you requested actually contained any of your transactions.