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TFM: mp_exptmod_ex didn't handle exceptional cases

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fp_exptmod_ex() changed to match execptional case handling in
fp_exptmod().
This commit is contained in:
Sean Parkinson
2022-06-16 10:39:23 +10:00
parent fb704774a0
commit 8145ee6cef
1 changed files with 12 additions and 5 deletions
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17
wolfcrypt/src/tfm.c
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@ -2895,14 +2895,21 @@ int fp_exptmod_ex(fp_int * G, fp_int * X, int digits, fp_int * P, fp_int * Y)
int x = fp_count_bits (X);
#endif
if (fp_iszero(G)) {
/* handle modulus of zero and prevent overflows */
if (fp_iszero(P) || (P->used > (FP_SIZE/2))) {
return FP_VAL;
}
if (fp_isone(P)) {
fp_set(Y, 0);
return FP_OKAY;
}
/* prevent overflows */
if (P->used > (FP_SIZE/2)) {
return FP_VAL;
if (fp_iszero(X)) {
fp_set(Y, 1);
return FP_OKAY;
}
if (fp_iszero(G)) {
fp_set(Y, 0);
return FP_OKAY;
}
#if defined(WOLFSSL_ESP32WROOM32_CRYPT_RSA_PRI) && \