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Merge pull request #2621 from JacobBarthelmeh/SanityChecks

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sanity check on "a" input to invmod
This commit is contained in:
David Garske
2019-12-02 10:57:01 -08:00
committed by GitHub
parent bfaa970d84 2efa91632e
commit 7e45ae2ec6
2 changed files with 7 additions and 2 deletions
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4
wolfcrypt/src/integer.c
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@ -966,8 +966,8 @@ int wolfcrypt_mp_invmod(mp_int * a, mp_int * b, mp_int * c)
int mp_invmod (mp_int * a, mp_int * b, mp_int * c) int mp_invmod (mp_int * a, mp_int * b, mp_int * c)
#endif #endif
{ {
/* b cannot be negative */ /* b cannot be negative or zero, and can not divide by 0 (1/a mod b) */
if (b->sign == MP_NEG || mp_iszero(b) == MP_YES) { if (b->sign == MP_NEG || mp_iszero(b) == MP_YES || mp_iszero(a) == MP_YES) {
return MP_VAL; return MP_VAL;
} }

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);