/* Validates an EC public key as described in Section 5.2.2 of
* X9.62. The ECDH primitive when used without the cofactor does
* not address small subgroup attacks, which may occur when the
* public key is not valid. These attacks can be prevented by
* validating the public key before using ECDH.
*/
SECStatus
EC_ValidatePublicKey(ECParams *ecParams, SECItem *publicValue)
{
#ifndef NSS_DISABLE_ECC
mp_int Px, Py;
ECGroup *group = NULL;
SECStatus rv = SECFailure;
mp_err err = MP_OKAY;
int len;
if (!ecParams || !publicValue) {
PORT_SetError(SEC_ERROR_INVALID_ARGS);
return SECFailure;
}
/* NOTE: We only support uncompressed points for now */
len = (ecParams->fieldID.size + 7) >> 3;
if (publicValue->data[0] != EC_POINT_FORM_UNCOMPRESSED) {
PORT_SetError(SEC_ERROR_UNSUPPORTED_EC_POINT_FORM);
return SECFailure;
} else if (publicValue->len != (2 * len + 1)) {
PORT_SetError(SEC_ERROR_BAD_KEY);
return SECFailure;
}
MP_DIGITS(&Px) = 0;
MP_DIGITS(&Py) = 0;
CHECK_MPI_OK( mp_init(&Px) );
CHECK_MPI_OK( mp_init(&Py) );
/* Initialize Px and Py */
CHECK_MPI_OK( mp_read_unsigned_octets(&Px, publicValue->data + 1, (mp_size) len) );
CHECK_MPI_OK( mp_read_unsigned_octets(&Py, publicValue->data + 1 + len, (mp_size) len) );
/* construct from named params */
group = ECGroup_fromName(ecParams->name);
if (group == NULL) {
/*
* ECGroup_fromName fails if ecParams->name is not a valid
* ECCurveName value, or if we run out of memory, or perhaps
* for other reasons. Unfortunately if ecParams->name is a
* valid ECCurveName value, we don't know what the right error
* code should be because ECGroup_fromName doesn't return an
* error code to the caller. Set err to MP_UNDEF because
* that's what ECGroup_fromName uses internally.
*/
if ((ecParams->name <= ECCurve_noName) ||
(ecParams->name >= ECCurve_pastLastCurve)) {
err = MP_BADARG;
} else {
err = MP_UNDEF;
}
goto cleanup;
}
/* validate public point */
if ((err = ECPoint_validate(group, &Px, &Py)) < MP_YES) {
if (err == MP_NO) {
PORT_SetError(SEC_ERROR_BAD_KEY);
rv = SECFailure;
err = MP_OKAY; /* don't change the error code */
}
goto cleanup;
}
rv = SECSuccess;
cleanup:
ECGroup_free(group);
mp_clear(&Px);
mp_clear(&Py);
if (err) {
MP_TO_SEC_ERROR(err);
rv = SECFailure;
}
return rv;
#else
PORT_SetError(SEC_ERROR_UNSUPPORTED_KEYALG);
return SECFailure;
#endif /* NSS_DISABLE_ECC */
}
/* Performs basic tests of elliptic curve cryptography over prime fields.
* If tests fail, then it prints an error message, aborts, and returns an
* error code. Otherwise, returns 0. */
int
ectest_curve_GFp(ECGroup *group, int ectestPrint, int ectestTime,
int generic)
{
mp_int one, order_1, gx, gy, rx, ry, n;
int size;
mp_err res;
char s[1000];
/* initialize values */
MP_CHECKOK(mp_init(&one));
MP_CHECKOK(mp_init(&order_1));
MP_CHECKOK(mp_init(&gx));
MP_CHECKOK(mp_init(&gy));
MP_CHECKOK(mp_init(&rx));
MP_CHECKOK(mp_init(&ry));
MP_CHECKOK(mp_init(&n));
MP_CHECKOK(mp_set_int(&one, 1));
MP_CHECKOK(mp_sub(&group->order, &one, &order_1));
/* encode base point */
if (group->meth->field_dec) {
MP_CHECKOK(group->meth->field_dec(&group->genx, &gx, group->meth));
MP_CHECKOK(group->meth->field_dec(&group->geny, &gy, group->meth));
} else {
MP_CHECKOK(mp_copy(&group->genx, &gx));
MP_CHECKOK(mp_copy(&group->geny, &gy));
}
if (ectestPrint) {
/* output base point */
printf(" base point P:\n");
MP_CHECKOK(mp_toradix(&gx, s, 16));
printf(" %s\n", s);
MP_CHECKOK(mp_toradix(&gy, s, 16));
printf(" %s\n", s);
if (group->meth->field_enc) {
printf(" base point P (encoded):\n");
MP_CHECKOK(mp_toradix(&group->genx, s, 16));
printf(" %s\n", s);
MP_CHECKOK(mp_toradix(&group->geny, s, 16));
printf(" %s\n", s);
}
}
#ifdef ECL_ENABLE_GFP_PT_MUL_AFF
/* multiply base point by order - 1 and check for negative of base
* point */
MP_CHECKOK(ec_GFp_pt_mul_aff(&order_1, &group->genx, &group->geny, &rx, &ry, group));
if (ectestPrint) {
printf(" (order-1)*P (affine):\n");
MP_CHECKOK(mp_toradix(&rx, s, 16));
printf(" %s\n", s);
MP_CHECKOK(mp_toradix(&ry, s, 16));
printf(" %s\n", s);
}
MP_CHECKOK(group->meth->field_neg(&ry, &ry, group->meth));
if ((mp_cmp(&rx, &group->genx) != 0) || (mp_cmp(&ry, &group->geny) != 0)) {
printf(" Error: invalid result (expected (- base point)).\n");
res = MP_NO;
goto CLEANUP;
}
#endif
#ifdef ECL_ENABLE_GFP_PT_MUL_AFF
/* multiply base point by order - 1 and check for negative of base
* point */
MP_CHECKOK(ec_GFp_pt_mul_jac(&order_1, &group->genx, &group->geny, &rx, &ry, group));
if (ectestPrint) {
printf(" (order-1)*P (jacobian):\n");
MP_CHECKOK(mp_toradix(&rx, s, 16));
printf(" %s\n", s);
MP_CHECKOK(mp_toradix(&ry, s, 16));
printf(" %s\n", s);
}
MP_CHECKOK(group->meth->field_neg(&ry, &ry, group->meth));
if ((mp_cmp(&rx, &group->genx) != 0) || (mp_cmp(&ry, &group->geny) != 0)) {
printf(" Error: invalid result (expected (- base point)).\n");
res = MP_NO;
goto CLEANUP;
}
#endif
/* multiply base point by order - 1 and check for negative of base
* point */
MP_CHECKOK(ECPoint_mul(group, &order_1, NULL, NULL, &rx, &ry));
if (ectestPrint) {
printf(" (order-1)*P (ECPoint_mul):\n");
MP_CHECKOK(mp_toradix(&rx, s, 16));
printf(" %s\n", s);
MP_CHECKOK(mp_toradix(&ry, s, 16));
printf(" %s\n", s);
}
MP_CHECKOK(mp_submod(&group->meth->irr, &ry, &group->meth->irr, &ry));
if ((mp_cmp(&rx, &gx) != 0) || (mp_cmp(&ry, &gy) != 0)) {
printf(" Error: invalid result (expected (- base point)).\n");
res = MP_NO;
goto CLEANUP;
}
/* multiply base point by order - 1 and check for negative of base
* point */
MP_CHECKOK(ECPoint_mul(group, &order_1, &gx, &gy, &rx, &ry));
if (ectestPrint) {
printf(" (order-1)*P (ECPoint_mul):\n");
MP_CHECKOK(mp_toradix(&rx, s, 16));
printf(" %s\n", s);
MP_CHECKOK(mp_toradix(&ry, s, 16));
printf(" %s\n", s);
}
MP_CHECKOK(mp_submod(&group->meth->irr, &ry, &group->meth->irr, &ry));
if ((mp_cmp(&rx, &gx) != 0) || (mp_cmp(&ry, &gy) != 0)) {
printf(" Error: invalid result (expected (- base point)).\n");
res = MP_NO;
goto CLEANUP;
}
#ifdef ECL_ENABLE_GFP_PT_MUL_AFF
/* multiply base point by order and check for point at infinity */
MP_CHECKOK(ec_GFp_pt_mul_aff(&group->order, &group->genx, &group->geny, &rx, &ry,
group));
if (ectestPrint) {
printf(" (order)*P (affine):\n");
MP_CHECKOK(mp_toradix(&rx, s, 16));
printf(" %s\n", s);
MP_CHECKOK(mp_toradix(&ry, s, 16));
printf(" %s\n", s);
}
if (ec_GFp_pt_is_inf_aff(&rx, &ry) != MP_YES) {
printf(" Error: invalid result (expected point at infinity).\n");
res = MP_NO;
goto CLEANUP;
}
#endif
#ifdef ECL_ENABLE_GFP_PT_MUL_JAC
/* multiply base point by order and check for point at infinity */
MP_CHECKOK(ec_GFp_pt_mul_jac(&group->order, &group->genx, &group->geny, &rx, &ry,
group));
if (ectestPrint) {
printf(" (order)*P (jacobian):\n");
MP_CHECKOK(mp_toradix(&rx, s, 16));
printf(" %s\n", s);
MP_CHECKOK(mp_toradix(&ry, s, 16));
printf(" %s\n", s);
}
if (ec_GFp_pt_is_inf_aff(&rx, &ry) != MP_YES) {
printf(" Error: invalid result (expected point at infinity).\n");
res = MP_NO;
goto CLEANUP;
}
#endif
/* multiply base point by order and check for point at infinity */
MP_CHECKOK(ECPoint_mul(group, &group->order, NULL, NULL, &rx, &ry));
if (ectestPrint) {
printf(" (order)*P (ECPoint_mul):\n");
MP_CHECKOK(mp_toradix(&rx, s, 16));
printf(" %s\n", s);
MP_CHECKOK(mp_toradix(&ry, s, 16));
printf(" %s\n", s);
}
if (ec_GFp_pt_is_inf_aff(&rx, &ry) != MP_YES) {
printf(" Error: invalid result (expected point at infinity).\n");
res = MP_NO;
goto CLEANUP;
}
/* multiply base point by order and check for point at infinity */
MP_CHECKOK(ECPoint_mul(group, &group->order, &gx, &gy, &rx, &ry));
if (ectestPrint) {
printf(" (order)*P (ECPoint_mul):\n");
MP_CHECKOK(mp_toradix(&rx, s, 16));
printf(" %s\n", s);
MP_CHECKOK(mp_toradix(&ry, s, 16));
printf(" %s\n", s);
}
if (ec_GFp_pt_is_inf_aff(&rx, &ry) != MP_YES) {
printf(" Error: invalid result (expected point at infinity).\n");
res = MP_NO;
goto CLEANUP;
}
/* check that (order-1)P + (order-1)P + P == (order-1)P */
MP_CHECKOK(ECPoints_mul(group, &order_1, &order_1, &gx, &gy, &rx, &ry));
MP_CHECKOK(ECPoints_mul(group, &one, &one, &rx, &ry, &rx, &ry));
if (ectestPrint) {
printf(" (order-1)*P + (order-1)*P + P == (order-1)*P (ECPoints_mul):\n");
MP_CHECKOK(mp_toradix(&rx, s, 16));
printf(" %s\n", s);
MP_CHECKOK(mp_toradix(&ry, s, 16));
printf(" %s\n", s);
}
MP_CHECKOK(mp_submod(&group->meth->irr, &ry, &group->meth->irr, &ry));
if ((mp_cmp(&rx, &gx) != 0) || (mp_cmp(&ry, &gy) != 0)) {
printf(" Error: invalid result (expected (- base point)).\n");
res = MP_NO;
goto CLEANUP;
}
/* test validate_point function */
if (ECPoint_validate(group, &gx, &gy) != MP_YES) {
printf(" Error: validate point on base point failed.\n");
res = MP_NO;
goto CLEANUP;
}
MP_CHECKOK(mp_add_d(&gy, 1, &ry));
if (ECPoint_validate(group, &gx, &ry) != MP_NO) {
printf(" Error: validate point on invalid point passed.\n");
res = MP_NO;
goto CLEANUP;
}
if (ectestTime) {
/* compute random scalar */
size = mpl_significant_bits(&group->meth->irr);
if (size < MP_OKAY) {
goto CLEANUP;
}
MP_CHECKOK(mpp_random_size(&n, (size + ECL_BITS - 1) / ECL_BITS));
MP_CHECKOK(group->meth->field_mod(&n, &n, group->meth));
/* timed test */
if (generic) {
#ifdef ECL_ENABLE_GFP_PT_MUL_AFF
M_TimeOperation(MP_CHECKOK(ec_GFp_pt_mul_aff(&n, &group->genx, &group->geny, &rx, &ry,
group)),
100);
#endif
M_TimeOperation(MP_CHECKOK(ECPoint_mul(group, &n, NULL, NULL, &rx, &ry)),
100);
M_TimeOperation(MP_CHECKOK(ECPoints_mul(group, &n, &n, &gx, &gy, &rx, &ry)), 100);
} else {
M_TimeOperation(MP_CHECKOK(ECPoint_mul(group, &n, NULL, NULL, &rx, &ry)),
100);
M_TimeOperation(MP_CHECKOK(ECPoint_mul(group, &n, &gx, &gy, &rx, &ry)),
100);
M_TimeOperation(MP_CHECKOK(ECPoints_mul(group, &n, &n, &gx, &gy, &rx, &ry)), 100);
}
}
CLEANUP:
mp_clear(&one);
mp_clear(&order_1);
mp_clear(&gx);
mp_clear(&gy);
mp_clear(&rx);
mp_clear(&ry);
mp_clear(&n);
if (res != MP_OKAY) {
printf(" Error: exiting with error value %i\n", res);
}
return res;
}
