How to have custom BTC address

[Lionel]

I've seen around some custom-made btc addresses, for example

1Payday1y58nDwp1t......

notice the "Payday", some pools have that word in the address from which they send you the withdrawal

how did they choose that?
i'm not savvy to the inner workings of btc, but when you generate a new address i thought it's choosen at random by the network.

maybe you can "ask the network" if a specific address is already in use, and if not you can create it

[DannyHamilton]

I've seen around some custom-made btc addresses, for example

1Payday1y58nDwp1t......

notice the "Payday", some pools have that word in the address from which they send you the withdrawal

how did they choose that?
i'm not savvy to the inner workings of btc, but when you generate a new address i thought it's choosen at random by the network.

maybe you can "ask the network" if a specific address is already in use, and if not you can create it

They generate a random address. Then they look to see if that random address starts with the letters they want.  If it doesn't, then they throw out the address and repeat the process.  They run a computer program that does this as fast as possible and try millions or billions of random addresses until they stumble across one that starts the way they want it to.

For more information, search for VanityGen

[mintodev]

There is a computer program which will generate vanity address. Try vanitygen.

[jimhsu]

As far as "in use" ... I wouldn't worry about that. There are about (33-13)^58 = 2.9 * 10^75 addresses potentially out there that start with "1Payday". To get an idea of how that big that number is: If every single star in the universe had an earth-like planet, and you counted every single grain of sand on these planets .. that wouldn't come even close to that number.

[jparsley]

Use vanitygen

[Bobsurplus]

You can use vanitygen. I got a few cool EMC2 addresses thanks to vanitygen.

[fbueller]

Clients don't actually check if an address has been used before - its that unlikely.

[Light]

Use vanitygen

Just out of reference, @OP if you're planning to create a vanity address and you have a decent GPU - look into using oclvanitygen rather than just vanitygen as your GPU will be a lot faster at brute-forcing keys than your CPU in most cases.