Reusing deposit address / I still don't understand.

[cmbconcretefire]

I pretty much gave up on my safety concerns with creating my own wallet and bought a Trezor last night. (this is a big issue for BTC going forward imho)

Anyway, I hear over and over and over again to NEVER reuse any address.....and frankly, that just seems completely stupid to me.

Let's assume by some miracle of God that I was able to generate a 100% secure public address and private key pair. Assume the private key is never used to move the btc except for a SINGLE TIME at some point in the far future. Why would it not be completely safe to deposit btc to that public address on multiple occasions?

Essentially, that public address would be a "savings account." Deposits only. Coins (all of them) moved at once a single time in the future to perhaps two or three new public "savings accounts." For safety concerns or whatever.

There is a complete contradiction in the BTC world. "NEVER USE THE SAME ADDRESS MORE THAN ONCE." Yet at the same time "GIVE OUT YOUR PUBLIC ADDRESS TO ANYONE YOU LIKE." -----WTF???

[Velkro]

Let's assume by some miracle of God that I was able to generate a 100% secure public address and private key pair.

Every created address is safe as long as you using not compromised RNG (random number generator).
There were very rare cases when there was faulty/compromised RNG, so dont be afraid of that.

Not reusing addresses was guide to more anonymity in your transactions, nothing more, so don't be afraid to reuse addresses.

[achow101]

Not reusing addresses has two parts, a security and a privacy part. It is primarily for privacy. If you use only one or a few addresses, then everyone that you send money to will know exactly how much money you have. Anyone who sends money to you will know exactly how much money you have. This is not necessarily something that you would want. Additionally, everyone who knows of your address(es) would be able to see exactly how much money you are spending and who you are spending to. This is not necessarily something that you would want people to know.

Regarding security, if ECDSA were to be broken in such a way that a private key could be derived from the public key, then reusing addresses means that attackers could steal all of your Bitcoin. You can receive as much Bitcoin as you want, so long as you don't spend. As soon as you spend, you must move all of the Bitcoin out of that address and to another one. This is because addresses are actually hashes of the public key. The public key is only revealed once you spend the Bitcoin. If you were to reuse addresses, then it is potentially possible for someone to reverse the public key in order to recover the private key and steal all of your money.

[DannyHamilton]

Let's assume by some miracle of God that I was able to generate a 100% secure public address and private key pair. Assume the private key is never used to move the btc except for a SINGLE TIME at some point in the far future. Why would it not be completely safe to deposit btc to that public address on multiple occasions?

It would be completely secure.

It would not be completely private, and because it is not completely private, you are not completely safe (from anyone that might want to use knowledge of your finances against you).

Essentially, that public address would be a "savings account."
- snip -
in the future to perhaps two or three new public "savings accounts."
- snip -

It's this habit of thinking of bitcoin addresses as account numbers that seems to cause a lot of confusion for people.  A bitcoin address is more like an invoice number.  It is a way to track who paid you, when they paid you, and what they paid you for.  You certain *can* re-use an invoice number, but why would you?  It just leads to confusion.  Instead, pretty much everyone that uses invoice numbers, generates a brand new invoice number for each and every invoice they are expecting payment on.

There is a complete contradiction in the BTC world. "NEVER USE THE SAME ADDRESS MORE THAN ONCE." Yet at the same time "GIVE OUT YOUR PUBLIC ADDRESS TO ANYONE YOU LIKE." -----WTF???

Anyone that is telling you to "give out your public address to anyone you like" doesn't understand bitcoin and is giving you bad advice.  The contradiction is because knowledgeable people keep telling you not to use the same address more than once, and unknowledgeable people are telling you to generate a single address and re-use it.  You are treating both of these sources of information as a single "BTC world", when in reality they are two very different groups.

The very small convenience that you get by re-using an address is generally not worth it given the amount of privacy, security, safety, and information that you gain by using each address only once.

[Qartersa]

I pretty much gave up on my safety concerns with creating my own wallet and bought a Trezor last night. (this is a big issue for BTC going forward imho)

Anyway, I hear over and over and over again to NEVER reuse any address.....and frankly, that just seems completely stupid to me.

Let's assume by some miracle of God that I was able to generate a 100% secure public address and private key pair. Assume the private key is never used to move the btc except for a SINGLE TIME at some point in the far future. Why would it not be completely safe to deposit btc to that public address on multiple occasions?

Essentially, that public address would be a "savings account." Deposits only. Coins (all of them) moved at once a single time in the future to perhaps two or three new public "savings accounts." For safety concerns or whatever.

There is a complete contradiction in the BTC world. "NEVER USE THE SAME ADDRESS MORE THAN ONCE." Yet at the same time "GIVE OUT YOUR PUBLIC ADDRESS TO ANYONE YOU LIKE." -----WTF???

I use the same addresses over and over again. So far I haven't had any problems with it. If you secure your private key, there would be no problem with it. No one can steal your coins if you secure your private key very well.

[Mastsetad]

Reusing the same address multiple times even after the deposit address gets changed after every transaction is probably not a problem as long as you don't care that people see what happened in that address in past, because if you keep receiving bitcoins in the same address anyone would know if when and how many transactions has been done to that address, so for more secure and anonymous transactions people use different deposit address, there is no other reason behind that.

[John3D]

By keeping every transaction on the same address , you're giving up privacy , by accessing a single address anyone will be able to see every transaction you've made.

Take a donation address for example, many keep the same address for donations to ease the donation process, but that also make you able to see how much donations were giving and the average donation value. if you are the mananger of such organization that may work against you on a fund raising....

Your public information more often than not is working against you, so be very careful about what people can find about you and how easy they can gather information about you. 

[Seansky]

Reusing address is ok if it is just for personal use like payment etc and receiving coins but reusing address in some instances are not ok but most of the time it is safe to reuse your btc address. The only thing I can say is that get a bitcoin address where you'll just store bitcoins and get another addresses that you will use for transactions to maximize your anonymity. Just remember to use bitcoin mixers and the likes for full anonymity if you want it.

[Chris!]

If you don't care about privacy you should still care about security. Here's a quote from Bitcoin Wiki

Multiple situations have been found where more than one digital signature can be used to calculate the private key needed to spend bitcoins.

It's less secure to use an address over and over again.