kc3-lang/libtommath/bn_mp_dr_is_modulus.c

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• Hash : 079b0f65
  Author :
  Date : 2015-10-30T17:55:29
  

  Getting ready for v0.43.0 release Also updated my email address... Signed-off-by: Tom St Denis <tstdenis82@gmail.com>

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• bn_mp_dr_is_modulus.c

• #include <tommath.h>
  #ifdef BN_MP_DR_IS_MODULUS_C
  /* LibTomMath, multiple-precision integer library -- Tom St Denis
   *
   * LibTomMath is a library that provides multiple-precision
   * integer arithmetic as well as number theoretic functionality.
   *
   * The library was designed directly after the MPI library by
   * Michael Fromberger but has been written from scratch with
   * additional optimizations in place.
   *
   * The library is free for all purposes without any express
   * guarantee it works.
   *
   * Tom St Denis, tstdenis82@gmail.com, http://libtom.org
   */
  
  /* determines if a number is a valid DR modulus */
  int mp_dr_is_modulus(mp_int *a)
  {
     int ix;
  
     /* must be at least two digits */
     if (a->used < 2) {
        return 0;
     }
  
     /* must be of the form b**k - a [a <= b] so all
      * but the first digit must be equal to -1 (mod b).
      */
     for (ix = 1; ix < a->used; ix++) {
         if (a->dp[ix] != MP_MASK) {
            return 0;
         }
     }
     return 1;
  }
  
  #endif
  
  /* $Source$ */
  /* $Revision$ */
  /* $Date$ */
  

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