File : fz_prime.ads

   1 ------------------------------------------------------------------------------
   2 ------------------------------------------------------------------------------
   3 -- This file is part of 'Finite Field Arithmetic', aka 'FFA'.               --
   4 --                                                                          --
   5 -- (C) 2019 Stanislav Datskovskiy ( www.loper-os.org )                      --
   6 -- http://wot.deedbot.org/17215D118B7239507FAFED98B98228A001ABFFC7.html     --
   7 --                                                                          --
   8 -- You do not have, nor can you ever acquire the right to use, copy or      --
   9 -- distribute this software ; Should you use this software for any purpose, --
  10 -- or copy and distribute it to anyone or in any manner, you are breaking   --
  11 -- the laws of whatever soi-disant jurisdiction, and you promise to         --
  12 -- continue doing so for the indefinite future. In any case, please         --
  13 -- always : read and understand any software ; verify any PGP signatures    --
  14 -- that you use - for any purpose.                                          --
  15 --                                                                          --
  16 -- See also http://trilema.com/2015/a-new-software-licensing-paradigm .     --
  17 ------------------------------------------------------------------------------
  18 ------------------------------------------------------------------------------
  19 
  20 with Words;   use Words;
  21 with FZ_Type; use FZ_Type;
  22 
  23 
  24 package FZ_Prime is
  25    
  26    pragma Pure;
  27    
  28    -- Constant-Time Miller-Rabin Test on N using the given Witness.
  29    -- Witness will be used as-is if it conforms to the valid bounds,
  30    -- i.e. 2 <= Witness <= N - 2; otherwise will be transformed into a
  31    -- valid Witness via modular arithmetic.
  32    -- Outputs ONE if N WAS FOUND composite; ZERO if NOT FOUND.
  33    -- Handles degenerate cases of N that M-R per se cannot eat:
  34    -- N=0, N=1: ALWAYS 'FOUND COMPOSITE'; 2, 3 - ALWAYS 'NOT FOUND'.
  35    -- If N is Even and not equal to 2, N is ALWAYS 'FOUND COMPOSITE.'
  36    -- For ALL other N, the output is equal to that of the M-R test.
  37    function FZ_MR_Composite_On_Witness(N       : in  FZ;
  38                                        Witness : in  FZ) return WBool
  39      with Pre => N'Length = Witness'Length;
  40    
  41 end FZ_Prime;