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lightning-sunbird  0.9+nobinonly
Defines | Functions
ecp_521.c File Reference
#include "ecp.h"
#include "mpi.h"
#include "mplogic.h"
#include "mpi-priv.h"
#include <stdlib.h>

Go to the source code of this file.

Defines

#define ECP521_DIGITS   ECL_CURVE_DIGITS(521)
#define FIRST_DIGIT   (ECP521_DIGITS-1)

Functions

mp_err ec_GFp_nistp521_mod (const mp_int *a, mp_int *r, const GFMethod *meth)
mp_err ec_GFp_nistp521_sqr (const mp_int *a, mp_int *r, const GFMethod *meth)
mp_err ec_GFp_nistp521_mul (const mp_int *a, const mp_int *b, mp_int *r, const GFMethod *meth)
mp_err ec_GFp_nistp521_div (const mp_int *a, const mp_int *b, mp_int *r, const GFMethod *meth)
mp_err ec_group_set_gfp521 (ECGroup *group, ECCurveName name)

Define Documentation

Definition at line 45 of file ecp_521.c.


Function Documentation

mp_err ec_GFp_nistp521_div ( const mp_int a,
const mp_int b,
mp_int r,
const GFMethod *  meth 
)

Definition at line 136 of file ecp_521.c.

{
       mp_err res = MP_OKAY;
       mp_int t;

       /* If a is NULL, then return the inverse of b, otherwise return a/b. */
       if (a == NULL) {
              return mp_invmod(b, &meth->irr, r);
       } else {
              /* MPI doesn't support divmod, so we implement it using invmod and 
               * mulmod. */
              MP_CHECKOK(mp_init(&t));
              MP_CHECKOK(mp_invmod(b, &meth->irr, &t));
              MP_CHECKOK(mp_mul(a, &t, r));
              MP_CHECKOK(ec_GFp_nistp521_mod(r, r, meth));
         CLEANUP:
              mp_clear(&t);
              return res;
       }
}

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mp_err ec_GFp_nistp521_mod ( const mp_int a,
mp_int r,
const GFMethod *  meth 
)

Definition at line 51 of file ecp_521.c.

{
       mp_err res = MP_OKAY;
       int a_bits = mpl_significant_bits(a);
       int i;

       /* m1, m2 are statically-allocated mp_int of exactly the size we need */
       mp_int m1;

       mp_digit s1[ECP521_DIGITS] = { 0 };

       MP_SIGN(&m1) = MP_ZPOS;
       MP_ALLOC(&m1) = ECP521_DIGITS;
       MP_USED(&m1) = ECP521_DIGITS;
       MP_DIGITS(&m1) = s1;

       if (a_bits < 521) {
              if (a==r) return MP_OKAY;
              return mp_copy(a, r);
       }
       /* for polynomials larger than twice the field size or polynomials 
        * not using all words, use regular reduction */
       if (a_bits > (521*2)) {
              MP_CHECKOK(mp_mod(a, &meth->irr, r));
       } else {
#define FIRST_DIGIT (ECP521_DIGITS-1)
              for (i = FIRST_DIGIT; i < MP_USED(a)-1; i++) {
                     s1[i-FIRST_DIGIT] = (MP_DIGIT(a, i) >> 9) 
                            | (MP_DIGIT(a, 1+i) << (MP_DIGIT_BIT-9));
              }
              s1[i-FIRST_DIGIT] = MP_DIGIT(a, i) >> 9;

              if ( a != r ) {
                     MP_CHECKOK(s_mp_pad(r,ECP521_DIGITS));
                     for (i = 0; i < ECP521_DIGITS; i++) {
                            MP_DIGIT(r,i) = MP_DIGIT(a, i);
                     }
              }
              MP_USED(r) = ECP521_DIGITS;
              MP_DIGIT(r,FIRST_DIGIT) &=  0x1FF;

              MP_CHECKOK(s_mp_add(r, &m1));
              if (MP_DIGIT(r, FIRST_DIGIT) & 0x200) {
                     MP_CHECKOK(s_mp_add_d(r,1));
                     MP_DIGIT(r,FIRST_DIGIT) &=  0x1FF;
              }
              s_mp_clamp(r);
       }

  CLEANUP:
       return res;
}

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mp_err ec_GFp_nistp521_mul ( const mp_int a,
const mp_int b,
mp_int r,
const GFMethod *  meth 
)

Definition at line 122 of file ecp_521.c.

{
       mp_err res = MP_OKAY;

       MP_CHECKOK(mp_mul(a, b, r));
       MP_CHECKOK(ec_GFp_nistp521_mod(r, r, meth));
  CLEANUP:
       return res;
}

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mp_err ec_GFp_nistp521_sqr ( const mp_int a,
mp_int r,
const GFMethod *  meth 
)

Definition at line 108 of file ecp_521.c.

{
       mp_err res = MP_OKAY;

       MP_CHECKOK(mp_sqr(a, r));
       MP_CHECKOK(ec_GFp_nistp521_mod(r, r, meth));
  CLEANUP:
       return res;
}

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mp_err ec_group_set_gfp521 ( ECGroup *  group,
ECCurveName  name 
)

Definition at line 161 of file ecp_521.c.

{
       if (name == ECCurve_NIST_P521) {
              group->meth->field_mod = &ec_GFp_nistp521_mod;
              group->meth->field_mul = &ec_GFp_nistp521_mul;
              group->meth->field_sqr = &ec_GFp_nistp521_sqr;
              group->meth->field_div = &ec_GFp_nistp521_div;
       }
       return MP_OKAY;
}

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