Must I always generate a new public address/key every time for both sending and

[crypto_jedi_ninja]

Hello. I just recently learned the importance of generating a new public address for every tx for BTC and ETH. It's supposedly not just for privacy but for security.

So my questions are:

Is it really possible for someone to deduce your private key if you use the same public key more than once?
If so, does this go for both sending and receiving txs?

You would think this would be the first thing someone would explain to people new to crypto. It took awhile before I even new I should have these Qs. I wonder why there isn't more clear explanations of this on the internet.

Thnx a lot for any help!

[Rath_]

Is it really possible for someone to deduce your private key if you use the same public key more than once?
If so, does this go for both sending and receiving txs?

No, that would be a catastrophe. You can reuse the same address as much as you want. If you are really concerned about your privacy then you should consider using a wallet which allows you to control your coins as well (e.g. Electrum which is also a light-client). Since Bitcoin transactions are basically inputs and outputs, you should worry more about not mixing specific addresses together.

Here you can learn a bit more about coin control.

[achow101]

Is it really possible for someone to deduce your private key if you use the same public key more than once?

Not with today's technology. A public key is supposed to be public. It helps in the future if quantum computers have enough qubits, but that's a long ways off. The main benefit of not reusing addresses is privacy.

You would think this would be the first thing someone would explain to people new to crypto. It took awhile before I even new I should have these Qs. I wonder why there isn't more clear explanations of this on the internet.

You must not be looking very hard because there are clear explanations of this. It is one of the most commonly asked questions. https://en.bitcoin.it/wiki/Address_reuse explains this.

[crypto_jedi_ninja]

Thanks for the answers.  That's a huge relief.  A couple threads on reddit seemed to say the opposite.

I will say it's not cool to assume someone's not looking that hard when I actually spent a couple hours searching trying to google different things. 

Thanks though!  Glad to hear it.

[Abdussamad]

Hello. I just recently learned the importance of generating a new public address for every tx for BTC and ETH. It's supposedly not just for privacy but for security.

Re: ETH I believe it doesn't use addresses but accounts and you're supposed to reuse them not make new ones but I'm not sure. You can probably ask in the altcoins section of this forum or on /r/ethereum.

With regard to BTC there are no sending addresses. You  give out a unique address each time you want to receive money. This makes it easy for you to track who sent you what and it makes it harder for others to track how much money you have. In your wallet when you go to the receive option it'll give you a new unused address each time so learn to use that.

Don't fixate too much on addresses. Your wallet has unlimited addresses and consider them as disposable lock boxes that people can deposit money into for you. Best to use a different address per transaction and label your addresses before you hand them out so that when you receive money you can tell who sent you how much.

[TheArchaeologist]

This is general information about not only bitcoin but all other cryptocurrencies as well, I think you should generate your private keys per every address you generate as well.

Uhm, ofcourse you need private keys for every address. The address is just another representation of the public key and there always is a 1:1 relationship from private key to public key.