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sanity check on "a" input to invmod

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Jacob Barthelmeh
2019-11-22 15:47:05 -07:00
parent edb07cf68e
commit 9a0a48e093
1 changed files with 5 additions and 0 deletions
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5
wolfcrypt/src/tfm.c
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@@ -1023,6 +1023,11 @@ int fp_invmod(fp_int *a, fp_int *b, fp_int *c)
#endif #endif
int neg; int neg;
/* [modified] sanity check on "a" */
if (fp_iszero(a) == FP_YES) {
return FP_VAL; /* can not divide by 0 here */
}
/* 2. [modified] b must be odd */ /* 2. [modified] b must be odd */
if (fp_iseven (b) == FP_YES) { if (fp_iseven (b) == FP_YES) {
return fp_invmod_slow(a,b,c); return fp_invmod_slow(a,b,c);