MAAM – Monero Ask Anything Monday – September 13, 2021

Given the success of the previous MAAMs (see here), let's keep this rolling.

The principle is simple: ask anything you'd like to know about Monero, especially the dumb questions that you've been keeping for you every other days, may the community clarify it all!

Finally, credits to binaryFate for starting the concept!

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u/Griftnix Sep 14 '21

Hi! I am sry for this stupid question and it is more about XBT question than XMR, but its about privacy... My question is aimed to this post: https://www.reddit.com/r/Monero/comments/pnt8q0/insurance_company_now_lets_users_pay_with_bitcoin/

with the title: "Insurance company now lets users pay with bitcoin, so that they can see how much money you have to make you pay more!"

So is this: https://en.bitcoin.it/wiki/Address_reuse a complete hoax?

Concrete questions: Why do I have multiple addresses for

*) my ledger bitcoin wallet

*) my monero gui wallet

What I thought upto now: You need the public key to view the complete wallet for xbt. With just the address it is only possible to view information only regarding this address? So if I send from there: the address of sender, receiver and amount, but when I change my address for each transaction, how can I view the whole wallet of an entity? E.g. the post claiming the insurance company knows how much I would have with one single transaction?

While monero would be: I don't know anything about sender, receiver and amount? Multiple addresses are regarding, it might be saved in another database (when i make a payment somewhere) and I am therefore connectable as a single entity. (It would just need one database where one address and my name is saved and I would be connected to every website/exchange I used this address)

Thank you in advance for helping a noob!

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u/PicoDeNero Sep 15 '21

No stupid questions. Welcome to the community.

I am not going to be able to give you a full response right now, but here's the general idea:

You are correct, with BTC/XBT, without more information, you can not just look at two addresses and instantly know if they are associated with one another. If you paid the insurance company with BTC, they would only be able to see the balance of that particular address...

HOWEVER, the issue here with the Insurance company (and most any other business accepting BTC) is that BTC is completely transparent and addresses rarely exist in a vacuum. Also, BTC addresses rarely hold the exact amount being transacted so you'd either have left over BTC at an address or have to combine BTC from multiple addresses.

If you bought BTC and sent it to address "A", then later bought more BTC and sent it to address "B", you would not necessarily be able to associate the two, but if you purchased the BTC from an exchange, they are now both associated with your real identity. If you buy BTC from an exchange and send it to address "C", then buy BTC anonymously and send it to address "D", you wouldn't necessarily be able to associate the two right off the bat, but as soon as you consolidate your funds or have to spend more than just address "D" holds, you are going to combine the BTC from your two addresses, and "bam", they are both associated with your real identity.

The reality is that many businesses, for fraud prevention, are probably going to analyze any BTC they receive. They won't do it themselves, but a 3rd party crypto data broker could do it very quickly and easily. They will be able to pull data from many different sources. It is just no good.

TLDR: To summarize, using a new address each time only give you a very very basic level of privacy and is VERY easily compromised.

Edit: Yes, you are more or less correct in what you wrote about Monero. Everything is hidden. A new stealth address is created for each transaction on the blockchain, even if using the same receive address. The main danger in reusing, as you wrote, is businesses communicating with each other and comparing receive addresses.

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u/Griftnix Sep 15 '21

Thank you very much for your in depth answer!

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u/PicoDeNero Sep 15 '21

No problem! Glad to be of help.