This uses the OS and the Seed(s).

CRandHex returns a hex encoded string that's floor(numDigits/2) * 2 long.

Returns a crand.Reader mixed with user-supplied entropy.

Mix additional bytes of randomness, e.g.

An address is a []byte, but hex-encoded even in JSON.

The main purpose of HexBytes is to enable HEX-encoding for json/encoding.