anchor.diff:      let padding n = Utils.repeat (byte n) |> Seq.take (n-1) |> Seq.toArray
       let foundBytes =
           let f = Utils.xorArrs [ code.[s+offset+1..s+15]; padding (16-offset); found ]
  -        printfn "%s" (found |> Utils.bytesToStr)
  +        printfn "%A %s" found (found |> Utils.bytesToStr)
           f
       let genGuess i: byte [] =
           Array.concat [| code.[s..(s+offset-1)];
  
positive.code:                        else evalGuesses ind xs 
          | _         -> (0uy, [||])
  
  let genBlock (bs: byte []) n =
      Utils.xorArr [|for _ in [0..n] do yield byte n |] bs.[(16-n)..]
      |> Array.ofSeq
  
  let disambiguate (b: byte, bs: byte []) : byte [] =
      let rec check pairs =
          match pairs with
              | []       -> Utils.xorArr [|b|] [|1uy|]
              | (n,x)::_ -> if paddingOracle x = false then check (List.tail pairs)
                            else genBlock x n
      [ for i in [1..15] do
            yield (i+1, Array.concat [| bs.[0..(15-i-1)];
                                        Utils.xorArr [|bs.[(15-i)]|] [|1uy|] 
                                        bs.[(15-i+1)..15] |]) ]
      |> check
  
  let decryptLastByte code start : byte [] =
  
negative.code:     let rnd = Random()
      strings.[rnd.Next 9] |> Convert.FromBase64String |> Utils.CBCEncrypt key iv
  
  let paddingOracle (code: byte []) : bool =
      code |> Utils.CBCDecryptKeepPad key iv |> Utils.validPKCS7
      
  let testDecrypt = testEncrypt |> paddingOracle
  