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ECC verify: validate r and s before any use

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SP code assumes r and s are valid values.
Code for ATECC508A, ATECC608A and CRYPTOCELL assumes that the r and s
are the size of the key when converting to byte arrays.
This commit is contained in:
Sean Parkinson
2020-11-19 09:01:03 +10:00
parent f5c2bef78f
commit b9a2725429
1 changed files with 30 additions and 10 deletions
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40
wolfcrypt/src/ecc.c
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@@ -6184,6 +6184,32 @@ int wc_ecc_verify_hash(const byte* sig, word32 siglen, const byte* hash,
}
#endif /* !NO_ASN */
static int wc_ecc_check_r_s_range(ecc_key* key, mp_int* r, mp_int* s)
{
int err;
DECLARE_CURVE_SPECS(curve, 1);
ALLOC_CURVE_SPECS(1);
err = wc_ecc_curve_load(key->dp, &curve, ECC_CURVE_FIELD_ORDER);
if (err != 0) {
FREE_CURVE_SPECS();
return err;
}
if (mp_iszero(r) || mp_iszero(s)) {
err = MP_ZERO_E;
}
if ((err == 0) && (mp_cmp(r, curve->order) != MP_LT)) {
return MP_VAL;
}
if ((err == 0) && (mp_cmp(s, curve->order) != MP_LT)) {
return MP_VAL;
}
wc_ecc_curve_free(curve);
FREE_CURVE_SPECS();
return err;
}
/**
Verify an ECC signature
@@ -6252,7 +6278,10 @@ int wc_ecc_verify_hash_ex(mp_int *r, mp_int *s, const byte* hash,
return ECC_BAD_ARG_E;
}
keySz = key->dp->size;
err = wc_ecc_check_r_s_range(key, r, s);
if (err != MP_OKAY) {
return err;
}
#if defined(WOLFSSL_ASYNC_CRYPT) && defined(WC_ASYNC_ENABLE_ECC) && \
defined(WOLFSSL_ASYNC_CRYPT_TEST)
@@ -6445,15 +6474,6 @@ int wc_ecc_verify_hash_ex(mp_int *r, mp_int *s, const byte* hash,
/* read in the specs for this curve */
err = wc_ecc_curve_load(key->dp, &curve, ECC_CURVE_FIELD_ALL);
/* check for zero */
if (err == MP_OKAY) {
if (mp_iszero(r) == MP_YES || mp_iszero(s) == MP_YES ||
mp_cmp(r, curve->order) != MP_LT ||
mp_cmp(s, curve->order) != MP_LT) {
err = MP_ZERO_E;
}
}
/* read hash */
if (err == MP_OKAY) {
/* we may need to truncate if hash is longer than key size */