# The randomness of vanitygen is secure enough?

If two people running `vanitygen 1abcdefg` What is the chance that both of the person will get the same public key & private key?

I hope that the answer is less than `0.0000001`. But for this `vanigygen` need to use random algorithm (not simple `while(true){ i++; test()}`).

My question is: Usually when I create wallet, using http://bitaddress.org I need to Move your mouse around to add some extra randomness, but vanitgygen do not do this method.

By inspecting the code of `vanitygen` in GitHub I see that they use random functions. Can I trust it? Is it really random? How it can be secure? Is it use the machine time or what?

If two people running vanitygen 1abcdefg What is the chance that both of the person will get the same public key & private key?

If a billion supercomputers each tried a billion keys per second for a billion years, the odds of a key collision would still be less than one in a billion.

I hope that the answer is less than 0.0000001.

Yes, much less.

But for this vanigygen need to use random algorithm (not simple while(true){ i++; test()}).

It just needs a random starting place. You can increment from there if you want to. The number of possible starting places has 77 digits when expressed in decimal notation.

• How computer can get genreate random starting place, that have 77 digits...? If it is just `new Date().valueOf()` it is not real random – Aminadav Glickshtein Jul 27 '16 at 13:01
• @Aminadav: You may want to read about cryptographically secure pseudorandom number generators. – Nate Eldredge Jul 27 '16 at 15:27
• @Aminadav This is a very well understood problem! Getting randomness right is hard and extremely important and the developers or crypto-currency software (at least, the competent ones) are very careful to get it right. Often sources of real physical randomness are used such as shot noise, microscopic zone temperature variations, and turbulent shear forces. (Real computers are not theoretically perfect machines, they meet the analog physical world in measurable ways.) – David Schwartz Jul 27 '16 at 16:12
• That my question if I can trust this open source software vanitygen. How the choose a random problem? What is it based on? – Aminadav Glickshtein Jul 27 '16 at 18:09
• @nate. I have read the wiki. It tally about security. It doesn't explain how machine computer can Behar the forest initial state random number – Aminadav Glickshtein Jul 27 '16 at 18:12