Andy wrote:
4. Use the current seed as the random numbers directly. Will this solution provide 'good' uuids? That is, is this source of random numbers good enough?
You'll need to perform statistical tests to be sure, but: 1. On POSIX systems where /dev/urandom is available, it should be close to the best, at least in theory; 2. Under a typical use case where the application only generates one UUID, it should be as good as any other RNG seeded with its entire state, and should be better than a RNG seeded with a 32 bit seed; 3. In the multiple UUIDs case, I expect it to be competitive with any RNG, even though it only keeps 160 bits of state (another 160 bits - the old value of 'rd' - can also contribute, depending on the compiler and the use pattern).