prime.fs

 let getPrimes  (str:string)=
    let one=BigInteger.One
    let two=new BigInteger(2)
    let zero=BigInteger.Zero
    
    let  decomposePq(n: BigInteger): (BigInteger* BigInteger) =
      let f(x: BigInteger, c: BigInteger):BigInteger = ((x * x) % n + c) % n
      let rec rho(x: BigInteger, y: BigInteger, g: BigInteger, c: BigInteger): BigInteger =
       if (g.Equals(one)) then 
        let xx = f(x, c)
        let yy = f(f(y, c), c)
        let gg = BigInteger.GreatestCommonDivisor(n,BigInteger.Abs(xx - yy))
        rho(xx, yy, gg, c)
       else g

      let p =
       if (n % two = zero) then two
       else
        let count=n.GetByteCount()
      
        let c = BigInteger.Abs(rndBigInt count)
        let x = BigInteger.Abs(rndBigInt count)
        rho(x, x, one, c)
     
      let q = n / p
      if (q > p) then (p, q) else (q, p)
    decomposePq (BigInteger.Abs(BigInteger(Encoding.UTF8.GetBytes(str))))