How exchanges make wallet adresses?

[wsxdrfv]

See the following link to learn how to compute an address from a public key:
https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses

Thanks much!
So, ./bitcoind (now ./bitcoin-cli ?)  does not provide simple one function to make Address?

[ranochigo]

Thanks much!
So, ./bitcoind (now ./bitcoin-cli ?)  does not provide simple one function to make Address?

It does. The command is getnewaddress.

[DannyHamilton]

See the following link to learn how to compute an address from a public key:
https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses

Thanks much!
So, ./bitcoind (now ./bitcoin-cli ?)  does not provide simple one function to make Address?

As ranchigo explained, you can just make a request to the client if you prefer, but it is not necessary to install and run a full client just to create addresses if you don't want to.

Some people use the client.  Some people prefer to write their own software that is faster and less complicated.

[Kakmakr]

Where are these private keys kept? If they are created on the fly, it must be generated online and the keys stored online? This in my opinion is very risky.

The other alternative of generating it offline and storing only the public address in a online database, makes more sense. I know my local exchange does not allow for the signing of any address, so they are maintaining a high level of security with these private keys. < I still prefer to manage my own private keys, but if you have to use exchanges, you then have no choice>

It must be a massive and risky endeavour to extract all the forked coins from these millions of private keys for the bigger exchanges?

[wsxdrfv]

See the following link to learn how to compute an address from a public key:
https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses

Thanks much!
So, ./bitcoind (now ./bitcoin-cli ?)  does not provide simple one function to make Address?

As ranchigo explained, you can just make a request to the client if you prefer, but it is not necessary to install and run a full client just to create addresses if you don't want to.

Some people use the client.  Some people prefer to write their own software that is faster and less complicated.

How to write own software? So just use same algo that some coin uses, and just make address from that algo? Are there any example code?

[wsxdrfv]

Where are these private keys kept? If they are created on the fly, it must be generated online and the keys stored online? This in my opinion is very risky.

Why this is risky?

So if daemon is running on exchange's server, then it means that daemon's private key is also exist in daemon? So you means it is risky?

If hacker come in server, then he can know that daemon's private key?

[wsxdrfv]

Why this is risky? (bump)

So user can try http injection attack to know wallet's secret key?
When user click that [generate address] button?

[hushan]

For online bitcoin wallets, most exchanges will use HD(BIP32) wallets, it will generic the extended key offline, store the correspondent public key on the server, and it only needs to allocate an index number to each user, then new addresses can be generated on the fly whenever user requested a new address.
By using HD wallets, it is much easier to manager, because there is only one private key. Also it is much simple to operate, because each user can have as many new addresses as they want, technically 2³²-1 addresses, and no private key is needed to generate new addresses.

[wsxdrfv]

For online bitcoin wallets, most exchanges will use HD(BIP32) wallets, it will generic the extended key offline, store the correspondent public key on the server, and it only needs to allocate an index number to each user, then new addresses can be generated on the fly whenever user requested a new address.
By using HD wallets, it is much easier to manager, because there is only one private key. Also it is much simple to operate, because each user can have as many new addresses as they want, technically 2³²-1 addresses, and no private key is needed to generate new addresses.

Then what if the alt-coins that does not have HD wallet features?

And most exchange just give 1 address for each coin per 1 user. And user also does not need more than 1 address. And it(multiple addresses per coin per user) only confuses and make it complicated to manage from point of view of exchange.

Are there any actual reason for give more than 1 address?

So point is, you saying about make bunch of addresses before (like 1 million addresses) and store them in DB?

[wsxdrfv]

And how to make like 1 million bitcoin addresses? I am running bitcoind at my server.

so there I can use [ bitcoin-cli getnewaddress ]

then how to do it?

[bob123]

Why this is risky? (bump)

So user can try http injection attack to know wallet's secret key?
When user click that [generate address] button?

You don't have to store the private keys / seed on your online server just to create new addresses.
You could simply use the Master public key. Public keys (and therefore addresses) can be dervied from this key, without the risk of private keys getting exposed/compromised.

So point is, you saying about make bunch of addresses before (like 1 million addresses) and store them in DB?

This can definetely be done. It does not expose any private keys to theft.

[hushan]

For online bitcoin wallets, most exchanges will use HD(BIP32) wallets, it will generic the extended key offline, store the correspondent public key on the server, and it only needs to allocate an index number to each user, then new addresses can be generated on the fly whenever user requested a new address.
By using HD wallets, it is much easier to manager, because there is only one private key. Also it is much simple to operate, because each user can have as many new addresses as they want, technically 2³²-1 addresses, and no private key is needed to generate new addresses.

Then what if the alt-coins that does not have HD wallet features?

And most exchange just give 1 address for each coin per 1 user. And user also does not need more than 1 address. And it(multiple addresses per coin per user) only confuses and make it complicated to manage from point of view of exchange.

Are there any actual reason for give more than 1 address?

So point is, you saying about make bunch of addresses before (like 1 million addresses) and store them in DB?

If a coin does not have HD feature, then you will have to go to the old way, i.e. pre generate lots of keys and addresses, and assign them to customers.

Actually, uses DOES need multiple addresses, most exchanges let the use generate new addresses as they want.

The point of HD is, you don't make bunch of address beforehand, you can generate new addresses on demand, but you neither store multiple private keys(only one master key), nor do you need to store keys in db, you just need to store the hd key path. When transactions are needed, you can always generate keys from the key path.

[DannyHamilton]

And how to make like 1 million bitcoin addresses? I am running bitcoind at my server.

Are you creating an exchange?



Please let us know what the name of your exchange will be.

[wsxdrfv]

And how to make like 1 million bitcoin addresses? I am running bitcoind at my server.

Are you creating an exchange?



Please let us know what the name of your exchange will be.

Yes not myself alone, but making exchange is true.
Why?

[wsxdrfv]

If a coin does not have HD feature, then you will have to go to the old way, i.e. pre generate lots of keys and addresses, and assign them to customers.

Actually, uses DOES need multiple addresses, most exchanges let the use generate new addresses as they want.

The point of HD is, you don't make bunch of address beforehand, you can generate new addresses on demand, but you neither store multiple private keys(only one master key), nor do you need to store keys in db, you just need to store the hd key path. When transactions are needed, you can always generate keys from the key path.

Thanks.
So what is HD key path?
and are there any  bad things to use old wallet? There are coins not having HD wallet listed on some exchange right?

And how about none-HD coin and just realtime generate when user request with coin daemon on server? Why this is dangerous?

[hieu81]

So at exchanges, so many coins. For each of them, they provide deposit addresses.

If you are engineer, need to implement that, how to do?

Maybe using that coin's daemon?

How is specific procedure of it?

Thanks.

Depending on the specific currency, they will use different wallet and management methods. For example, with XMR coin, they use a Payment ID, with Bitcoin or other coin using the same algorithm they will use for Public key!

[wsxdrfv]

How do you think this article? This says HD wallet's flaw?

https://bitcoinmagazine.com/articles/deterministic-wallets-advantages-flaw-1385450276/

[bob123]

Are you creating an exchange?



Please let us know what the name of your exchange will be.

Yes not myself alone, but making exchange is true.
Why?

Probably because he wants to make sure to never use your exchange.
Without offending you, but if you have to ask such basic questions i highly suspect your 'exchange' will be vulnerable to any kind of attacks.

DannyHamilton is one of the nice guys who ask you this question to never use your exchange.
But there are also another kind of people.. those who will definetely make use of your weak exchange to get a quick buck.

If you really want to open an exchange, i'd suggest you hire a professional team.

[wsxdrfv]

Are you creating an exchange?



Please let us know what the name of your exchange will be.

Yes not myself alone, but making exchange is true.
Why?

Probably because he wants to make sure to never use your exchange.
Without offending you, but if you have to ask such basic questions i highly suspect your 'exchange' will be vulnerable to any kind of attacks.

DannyHamilton is one of the nice guys who ask you this question to never use your exchange.
But there are also another kind of people.. those who will definetely make use of your weak exchange to get a quick buck.

If you really want to open an exchange, i'd suggest you hire a professional team.

Of course I am not in charge about security, professional will involve soon.
This is just curiosity and learn.

[The best one]

How to apply this to alt-coin?

Depends of your altcoin (especially the address prefix, which is 0x00 for bitcoin). Change prefix, recompile, should work.

As for me how exchange make wallet address  This depends on what you're trying to do.  If you don't mind the multiple receiving addresses holding balances, then use some wallet software which will give you as many addresses as you need, and it will let you select which addresses you want to send from Online wallet: http://www.blockchain.info If you really actually want to sweep coins from the receiving addresses into wallet address (perhaps you keep the private key of the wallet address offline for security), then you will need to build a small bot to periodically check the balances of the receiving addresses, and then make a payment to the wallet address - I don't believe there is a strong wallet service that currently has this functionality at the moment, but I look forward to be corrected thank you.