8 ms·

> prevent anyone from hiding from the tax collectors and police Only if you use chains with traceable transactions.

by klntsky 3y ago

v-erne 3y ago
I did not know this is possible - can You give an example of blockchain with this property?
- dmarcos 3y ago
  zcash is one. https://en.m.wikipedia.org/wiki/Zcash https://en.m.wikipedia.org/wiki/Zcash
- klntsky 3y ago
  Monero, and zero-knowledge ones: zcash and more recent Mina which supports smart contracts.
acdha 3y ago
You also have to only buy things available purely on that system from people you are certain don’t collaborate with the government. If all of those assumptions aren’t true, your activity can be tracked with increasing precision and the authorities will see local transactions which you can’t explain otherwise and demand explanations. The schemes Zcash and Monero use have never been tested at scale with a sophisticated adversary. The statistical methods used are probably fine for keeping your friends from knowing what you buy but it’s less clear that a government which can observe network traffic and receive KYC data from compliant merchants or compromised devices won’t be able to rule out some of the decoys over time, and since it’s a blockchain you’re gambling that this will hold true forever.
- BitwiseFool 3y ago
  I like to think the government has a unique and sophisticated rubber-hose attack, just auditing you.
  - acdha 3y ago
    That’s one of the big questions here: if repressive governments are in your threat model, does a given system mean a normal person is likely to leave too much data on their devices? It’s really easy to imagine checks on all of the phones seized from protesters, anyone suspected of spending beyond their reported income, etc. so something which doesn’t make it really easy to purge old history is pretty risky - not least because if they catch you hiring anything there’s a nasty problem of convincing them that there’s nothing more still hidden.
- klntsky 3y ago
  > The schemes Zcash and Monero use have never been tested at scale with a sophisticated adversary Monero's ring signatures are not the same as ZCash's zero-knowledge crypto. Monero obfuscates, but ZCash hides completely, cryptographically. https://z.cash/learn/is-zcash-traceable/ https://z.cash/learn/is-zcash-traceable/
  - acdha 3y ago
    That’s the hope anyway - even if the cryptography is perfect against all future attacks (remember they’ve already had at least one flaw in earlier versions) there are still things like timing attacks: https://crypto.stanford.edu/timings/ https://crypto.stanford.edu/timings/ Nation states are some of hardest attackers since they can do things like monitoring network traffic to correlate with chain activity or compel some fraction of the participants to surrender data. I know some smart people work on Zcash but there’s no safety net when all of the transactions are public and immutable.
soco 3y ago
It's incredible how often we must refer to this classic xkcd when talking about crypto "security": https://xkcd.com/538/ https://xkcd.com/538/

> prevent anyone from hiding from the tax collectors and police Only if you use chains with traceable transactions.

v-erne 3y ago

I did not know this is possible - can You give an example of blockchain with this property?

dmarcos 3y ago
zcash is one. https://en.m.wikipedia.org/wiki/Zcash https://en.m.wikipedia.org/wiki/Zcash
klntsky 3y ago
Monero, and zero-knowledge ones: zcash and more recent Mina which supports smart contracts.

acdha 3y ago

You also have to only buy things available purely on that system from people you are certain don’t collaborate with the government. If all of those assumptions aren’t true, your activity can be tracked with increasing precision and the authorities will see local transactions which you can’t explain otherwise and demand explanations. The schemes Zcash and Monero use have never been tested at scale with a sophisticated adversary. The statistical methods used are probably fine for keeping your friends from knowing what you buy but it’s less clear that a government which can observe network traffic and receive KYC data from compliant merchants or compromised devices won’t be able to rule out some of the decoys over time, and since it’s a blockchain you’re gambling that this will hold true forever.

BitwiseFool 3y ago
I like to think the government has a unique and sophisticated rubber-hose attack, just auditing you.
- acdha 3y ago
  That’s one of the big questions here: if repressive governments are in your threat model, does a given system mean a normal person is likely to leave too much data on their devices? It’s really easy to imagine checks on all of the phones seized from protesters, anyone suspected of spending beyond their reported income, etc. so something which doesn’t make it really easy to purge old history is pretty risky - not least because if they catch you hiring anything there’s a nasty problem of convincing them that there’s nothing more still hidden.
klntsky 3y ago
> The schemes Zcash and Monero use have never been tested at scale with a sophisticated adversary Monero's ring signatures are not the same as ZCash's zero-knowledge crypto. Monero obfuscates, but ZCash hides completely, cryptographically. https://z.cash/learn/is-zcash-traceable/ https://z.cash/learn/is-zcash-traceable/
- acdha 3y ago
  That’s the hope anyway - even if the cryptography is perfect against all future attacks (remember they’ve already had at least one flaw in earlier versions) there are still things like timing attacks: https://crypto.stanford.edu/timings/ https://crypto.stanford.edu/timings/ Nation states are some of hardest attackers since they can do things like monitoring network traffic to correlate with chain activity or compel some fraction of the participants to surrender data. I know some smart people work on Zcash but there’s no safety net when all of the transactions are public and immutable.

soco 3y ago

It's incredible how often we must refer to this classic xkcd when talking about crypto "security": https://xkcd.com/538/ https://xkcd.com/538/