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Fix fastmath and heapmath invmod to be consistent with sp-math.

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This commit is contained in:
jordan
2023-06-02 22:11:44 -05:00
parent 5604033902
commit db28d38ea3
2 changed files with 36 additions and 18 deletions
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17
wolfcrypt/src/integer.c
View File

@ -1058,7 +1058,7 @@ int mp_invmod (mp_int * a, mp_int * b, mp_int * c)
int fast_mp_invmod (mp_int * a, mp_int * b, mp_int * c)
{
mp_int x, y, u, v, B, D;
int res, neg, loop_check = 0;
int res, loop_check = 0;
/* 2. [modified] b must be odd */
if (mp_iseven (b) == MP_YES) {
@ -1080,6 +1080,12 @@ int fast_mp_invmod (mp_int * a, mp_int * b, mp_int * c)
goto LBL_ERR;
}
if (mp_iszero (&y) == MP_YES) {
/* invmod doesn't exist for this a and b */
res = MP_VAL;
goto LBL_ERR;
}
/* 3. u=x, v=y, A=1, B=0, C=0,D=1 */
if ((res = mp_copy (&x, &u)) != MP_OKAY) {
goto LBL_ERR;
@ -1168,7 +1174,6 @@ top:
}
/* b is now the inverse */
neg = a->sign;
while (D.sign == MP_NEG) {
if ((res = mp_add (&D, b, &D)) != MP_OKAY) {
goto LBL_ERR;
@ -1181,7 +1186,6 @@ top:
}
}
mp_exch (&D, c);
c->sign = neg;
res = MP_OKAY;
LBL_ERR:mp_clear(&x);
@ -1226,6 +1230,13 @@ int mp_invmod_slow (mp_int * a, mp_int * b, mp_int * c)
if ((res = mp_mod(a, b, &x)) != MP_OKAY) {
goto LBL_ERR;
}
if (mp_iszero (&x) == MP_YES) {
/* invmod doesn't exist for this a and b */
res = MP_VAL;
goto LBL_ERR;
}
if (mp_isone(&x)) {
res = mp_set(c, 1);
goto LBL_ERR;

37
wolfcrypt/src/tfm.c
View File

@ -1086,6 +1086,14 @@ static int fp_invmod_slow (fp_int * a, fp_int * b, fp_int * c)
}
fp_copy(b, y);
if (fp_iszero(x) == FP_YES) {
/* invmod doesn't exist for this a and b */
#ifdef WOLFSSL_SMALL_STACK
XFREE(x, NULL, DYNAMIC_TYPE_BIGINT);
#endif
return FP_VAL;
}
/* 2. [modified] if x,y are both even then return an error! */
if (fp_iseven(x) == FP_YES && fp_iseven(y) == FP_YES) {
#ifdef WOLFSSL_SMALL_STACK
@ -1258,7 +1266,6 @@ int fp_invmod(fp_int *a, fp_int *b, fp_int *c)
#else
fp_int *x, *y, *u, *v, *B, *D;
#endif
int neg;
int err;
if (b->sign == FP_NEG || fp_iszero(b) == FP_YES) {
@ -1288,17 +1295,6 @@ int fp_invmod(fp_int *a, fp_int *b, fp_int *c)
fp_init(u); fp_init(v);
fp_init(B); fp_init(D);
if (fp_cmp(a, b) != MP_LT) {
err = mp_mod(a, b, y);
if (err != FP_OKAY) {
#ifdef WOLFSSL_SMALL_STACK
XFREE(x, NULL, DYNAMIC_TYPE_BIGINT);
#endif
return err;
}
a = y;
}
if (fp_iszero(a) == FP_YES) {
#ifdef WOLFSSL_SMALL_STACK
XFREE(x, NULL, DYNAMIC_TYPE_BIGINT);
@ -1310,7 +1306,20 @@ int fp_invmod(fp_int *a, fp_int *b, fp_int *c)
fp_copy(b, x);
/* we need y = |a| */
fp_abs(a, y);
if ((err = mp_mod(a, b, y)) != FP_OKAY) {
#ifdef WOLFSSL_SMALL_STACK
XFREE(x, NULL, DYNAMIC_TYPE_BIGINT);
#endif
return err;
}
if (fp_iszero(y) == FP_YES) {
/* invmod doesn't exist for this a and b */
#ifdef WOLFSSL_SMALL_STACK
XFREE(x, NULL, DYNAMIC_TYPE_BIGINT);
#endif
return FP_VAL;
}
/* 3. u=x, v=y, A=1, B=0, C=0,D=1 */
fp_copy(x, u);
@ -1408,7 +1417,6 @@ top:
}
/* b is now the inverse */
neg = a->sign;
while (D->sign == FP_NEG) {
err = fp_add (D, b, D);
if (err != FP_OKAY) {
@ -1429,7 +1437,6 @@ top:
}
}
fp_copy (D, c);
c->sign = neg;
#ifdef WOLFSSL_SMALL_STACK
XFREE(x, NULL, DYNAMIC_TYPE_BIGINT);
#endif