Cyclic0007/wolfssl
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mp_invmod handles more inputs

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Value to invert: a
Modulus: b
integer.c - normal math
  - a is one, or a mod b is one
tfm.c - fast math
  - b is -ve (error), or b is zero
  - a is zero or a mod b is zero
This commit is contained in:
Sean Parkinson
2019-11-29 09:08:44 +10:00
parent b396ed0984
commit bd7a572a8f
2 changed files with 46 additions and 15 deletions
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31
wolfcrypt/src/integer.c
View File

@@ -1145,23 +1145,28 @@ int mp_invmod_slow (mp_int * a, mp_int * b, mp_int * c)
/* init temps */
if ((res = mp_init_multi(&x, &y, &u, &v,
&A, &B)) != MP_OKAY) {
return res;
return res;
}
/* init rest of tmps temps */
if ((res = mp_init_multi(&C, &D, 0, 0, 0, 0)) != MP_OKAY) {
mp_clear(&x);
mp_clear(&y);
mp_clear(&u);
mp_clear(&v);
mp_clear(&A);
mp_clear(&B);
return res;
mp_clear(&x);
mp_clear(&y);
mp_clear(&u);
mp_clear(&v);
mp_clear(&A);
mp_clear(&B);
return res;
}
/* x = a, y = b */
if ((res = mp_mod(a, b, &x)) != MP_OKAY) {
goto LBL_ERR;
goto LBL_ERR;
}
if (mp_isone(&x)) {
mp_set(c, 1);
res = MP_OKAY;
goto LBL_ERR;
}
if ((res = mp_copy (b, &y)) != MP_OKAY) {
goto LBL_ERR;
@@ -1198,10 +1203,10 @@ top:
if (mp_isodd (&A) == MP_YES || mp_isodd (&B) == MP_YES) {
/* A = (A+y)/2, B = (B-x)/2 */
if ((res = mp_add (&A, &y, &A)) != MP_OKAY) {
goto LBL_ERR;
goto LBL_ERR;
}
if ((res = mp_sub (&B, &x, &B)) != MP_OKAY) {
goto LBL_ERR;
goto LBL_ERR;
}
}
/* A = A/2, B = B/2 */
@@ -1223,10 +1228,10 @@ top:
if (mp_isodd (&C) == MP_YES || mp_isodd (&D) == MP_YES) {
/* C = (C+y)/2, D = (D-x)/2 */
if ((res = mp_add (&C, &y, &C)) != MP_OKAY) {
goto LBL_ERR;
goto LBL_ERR;
}
if ((res = mp_sub (&D, &x, &D)) != MP_OKAY) {
goto LBL_ERR;
goto LBL_ERR;
}
}
/* C = C/2, D = D/2 */