Generate random number ink!

Question

I am writing ink! contract to generate random number between min and max value. I found this article. Here we can generate random number between 0 to 99. Then I modified to generate random number between 0 to 14999. But I am testing for long time I never get value more than 252. Is there something wrong with this code? Someone please check this code. It is possible to generate random number between 0 to 14999 using this code or not?

Here is my code repo github

Answer 1

The Keccak256 hash algorithm produces a 256-bit (32-byte) hash, and its associated type Type is [u8; 32].

In your code you always take just output[0] of type u8 and your result is always less than u8::MAX, which is 255u8 as mentioned here. To use more bits from the generated hash you can change your code to something like:

let number_bytes = [output[0], output[1]];
let z = u16::from_be_bytes(number_bytes);
let number = z as u128 % (self.max_value + 1);