Single Cold Storage Address?

[ulhaq]

I am going to send my bitcoin from an exchange to a cold storage electrum wallet. I understand I can use a "receiving" address for it. Is it safe/recommended to send all my bitcoin to this one address? Or should I try to distribute the bitcoin among multiple addresses in my one electrum wallet? Eg, if someone gets lucky and by chance manages to brute-force the private key for that single address.

Initially I will probably make a small test transaction. If that works, is it ok to send the rest of the bitcoin to that same address, or should I get a new address from electrum (but in that case I have not tested that address)?

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[ranochigo]

I am going to send my bitcoin from an exchange to a cold storage electrum wallet. I understand I can use a "receiving" address for it. Is it safe/recommended to send all my bitcoin to this one address?

It is safe.

Or should I try to distribute the bitcoin among multiple addresses in my one electrum wallet? Eg, if someone gets lucky and by chance manages to brute-force the private key for that single address.

Initially I will probably make a small test transaction. If that works, is it ok to send the rest of the bitcoin to that same address, or should I get a new address from electrum (but in that case I have not tested that address)?

Honestly, the chances are so small that I would believe I can hit 5 blocks in a row on my 100GH/s USB miners solomining at the current difficulty before any of your addresses get compromised this way.

As long as your address hasn't had spend any of its input, it is not susceptible to quantum attacks so it won't affect you. Once you've sent a transaction, I would recommend sending them to a new change address, just in case it gets bruteforced (albeit with a relatively hard difficulty and little to no incentive for the attacker) in the far far future.

[pooya87]

the only reason why you'd want to split your coins among multiple keys is if you want more privacy. for example if you don't want the coins you spend be linked to your main stash which you are holding and not touching.

for example have 1 key containing 21BTC and never touch it but have another containing 1-3BTC which you use to spend from, trade, ...

as above poster said make sure to not reuse addresses. the reason is not brute force, it can not be brute forced that would mean bitcoin is dead
the reason is when you create a transaction you are revealing your public key and your public key (unlike your bitcoin address in base58) does not have the same hash function behind it.
it is like this:
your private key (if anyone has this, they have your money) ---- ECDSA ----> public key (this is irreversible but we don't know what will happen in 10 years. maybe someone found a flaw in it someday) --- RIPEMD160(SHA256) ----> bitcoin address in base58 (starting with 1 or 3) this is 2 times irreversible hash function which means a lot more security.
and this is one of the reasons they advise against address reuse.

[ulhaq]

the only reason why you'd want to split your coins among multiple keys is if you want more privacy. for example if you don't want the coins you spend be linked to your main stash which you are holding and not touching.

for example have 1 key containing 21BTC and never touch it but have another containing 1-3BTC which you use to spend from, trade, ...

as above poster said make sure to not reuse addresses. the reason is not brute force, it can not be brute forced that would mean bitcoin is dead
the reason is when you create a transaction you are revealing your public key and your public key (unlike your bitcoin address in base58) does not have the same hash function behind it.
it is like this:
your private key (if anyone has this, they have your money) ---- ECDSA ----> public key (this is irreversible but we don't know what will happen in 10 years. maybe someone found a flaw in it someday) --- RIPEMD160(SHA256) ----> bitcoin address in base58 (starting with 1 or 3) this is 2 times irreversible hash function which means a lot more security.
and this is one of the reasons they advise against address reuse.

So to clarify, the step that the non-reuse of a bitcoin address concerns is going backwards from the public key? The only reason not to re-use bitcoin addresses is that this step might be compromised at some future time?

When a bitcoin transaction occurs, does the public key become public to everyone, or just the recipient of the transaction?

[ranochigo]

So to clarify, the step that the non-reuse of a bitcoin address concerns is going backwards from the public key? The only reason not to re-use bitcoin addresses is that this step might be compromised at some future time?

No, the main issue lies with the privacy. Its fairly unlikely for your address to get compromised within the next decade, at least without significant difficulty.

When a bitcoin transaction occurs, does the public key become public to everyone, or just the recipient of the transaction?

Everyone. The public key is included in the transaction so as to verify that you have the rights to spend the inputs to another address.

[pooya87]

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and this is one of the reasons they advise against address reuse.

So to clarify, the step that the non-reuse of a bitcoin address concerns is going backwards from the public key? The only reason not to re-use bitcoin addresses is that this step might be compromised at some future time?

When a bitcoin transaction occurs, does the public key become public to everyone, or just the recipient of the transaction?

i said in the last line that it is one of the reasons, there are more which you can read about it here: https://en.bitcoin.it/wiki/Address_reuse and if ECDSA is compromised a lot of things will be harmed not just bitcoin.

as for your public key, everyone sees it because it is appended to the signature when you make a transaction. you can actually see it here: https://blockchain.info/q/pubkeyaddr/{your_btc_address_here}
replace {your_btc_address_here} with your bitcoin address and if you have ever made a transaction you can see your pubkey.

[ulhaq]

~
and this is one of the reasons they advise against address reuse.

So to clarify, the step that the non-reuse of a bitcoin address concerns is going backwards from the public key? The only reason not to re-use bitcoin addresses is that this step might be compromised at some future time?

When a bitcoin transaction occurs, does the public key become public to everyone, or just the recipient of the transaction?

i said in the last line that it is one of the reasons, there are more which you can read about it here: https://en.bitcoin.it/wiki/Address_reuse and if ECDSA is compromised a lot of things will be harmed not just bitcoin.

as for your public key, everyone sees it because it is appended to the signature when you make a transaction. you can actually see it here: https://blockchain.info/q/pubkeyaddr/{your_btc_address_here}
replace {your_btc_address_here} with your bitcoin address and if you have ever made a transaction you can see your pubkey.

Great, thanks, very useful link.

When I mentioned the "only reason", I meant the only security reason, because the privacy issue was already mentioned.

[Abdussamad]

Initially I will probably make a small test transaction. If that works, is it ok to send the rest of the bitcoin to that same address, or should I get a new address from electrum (but in that case I have not tested that address)?

Test transaction is unnecessary. Bitcoin addresses have checksums in them so electrum will refuse to send coins to an invalid address. OTOH addresses don't have to be registered with any central authority so there is never any check as to whether the address is controlled by anybody or not. Bottom line being that test transactions make no sense. Instead to confirm your control over the target address sign and then verify a message with its private key. Right click on the address in the seeded wallet (on the offline machine) and you will see the option to sign/verify messages with its private key.