[openssl-users] Certificate serialnumber?

[Salz, Rich]

> > the question: where does the serial number for this certificate come from?
> > is it random by default when nothing is said about it?

It will be random if (a) the serial file does not exist; and (b) you specify the -create_serial flag.  Otherwise it opens the file, reads the number (defaulting to zero if not exists) and increments it, updates the file, and uses that as the new serial number.