You can do better than 8, as mark-r said. Do as I mentioned, but batch requests. For example, if you generate 89 numbers from 0-128 inclusive at once, you'll

You can do better than 8, as mark-r said. Do as I mentioned, but batch requests. For example, if you generate 89 numbers from 0-128 inclusive at once, you'll need, on average, 624.3 bits of entropy to generate them, whereas the optimal is 624.0 bits. That's an average of 7.0 bits of entropy per number generated. (It works out to something like 1.00054 x optimal.) So, generate a number from 0 to 128^k-1, and split it base 129, for some value of k, returning the k random numbers generated this way. For sufficiently large k you will be able to use arbitrarily close to the optimal number of bits of entropy per request. Unfortunately, this requires you know in advance what the range of the random numbers to generate will be.