I'm starting to get my head around Bitcoin, Blockchain etc. but I want to learn more about private keys, their generation, and use.
As I understand any 128-bit sequence can be a private key which can, in turn, be used to generate a 32-bit address using a one-way function.
1. Is there a set of rules that narrow down what is a good private key?
2. Is there anything in place to avoid collisions (multiple private keys to one address) other than statistics?
Also, roughly how many public addresses are currently storing bitcoin?
Some mistakes in your text. Any
256bit number works as a private key, and addresses are
160bit.
1. There are no set of rules that narrow private keys, but my own opinion is that there should be. While it is unlikely that your private key would be really small, or close to 1/2 or 3/4 of the search space (psychological values, where humans could start searching for your key) You still would not want your private key to be there.
2. Nothing to avoid collisions, except the huge amount of possible keys, which makes a collision extremely improbable.
About 2 months ago there were:
~21600000 addresses containing some balance and
~661000 addresses containing > 1
BTC