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Diffstat (limited to 'crypto/ecc.c')
-rw-r--r--crypto/ecc.c42
1 files changed, 38 insertions, 4 deletions
diff --git a/crypto/ecc.c b/crypto/ecc.c
index 815541309a95..8facafd67802 100644
--- a/crypto/ecc.c
+++ b/crypto/ecc.c
@@ -1019,6 +1019,36 @@ out:
return ret;
}
+/* SP800-56A section 5.6.2.3.4 partial verification: ephemeral keys only */
+static int ecc_is_pubkey_valid_partial(const struct ecc_curve *curve,
+ struct ecc_point *pk)
+{
+ u64 yy[ECC_MAX_DIGITS], xxx[ECC_MAX_DIGITS], w[ECC_MAX_DIGITS];
+
+ /* Check 1: Verify key is not the zero point. */
+ if (ecc_point_is_zero(pk))
+ return -EINVAL;
+
+ /* Check 2: Verify key is in the range [1, p-1]. */
+ if (vli_cmp(curve->p, pk->x, pk->ndigits) != 1)
+ return -EINVAL;
+ if (vli_cmp(curve->p, pk->y, pk->ndigits) != 1)
+ return -EINVAL;
+
+ /* Check 3: Verify that y^2 == (x^3 + a·x + b) mod p */
+ vli_mod_square_fast(yy, pk->y, curve->p, pk->ndigits); /* y^2 */
+ vli_mod_square_fast(xxx, pk->x, curve->p, pk->ndigits); /* x^2 */
+ vli_mod_mult_fast(xxx, xxx, pk->x, curve->p, pk->ndigits); /* x^3 */
+ vli_mod_mult_fast(w, curve->a, pk->x, curve->p, pk->ndigits); /* a·x */
+ vli_mod_add(w, w, curve->b, curve->p, pk->ndigits); /* a·x + b */
+ vli_mod_add(w, w, xxx, curve->p, pk->ndigits); /* x^3 + a·x + b */
+ if (vli_cmp(yy, w, pk->ndigits) != 0) /* Equation */
+ return -EINVAL;
+
+ return 0;
+
+}
+
int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
const u64 *private_key, const u64 *public_key,
u64 *secret)
@@ -1046,16 +1076,20 @@ int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits,
goto out;
}
+ ecc_swap_digits(public_key, pk->x, ndigits);
+ ecc_swap_digits(&public_key[ndigits], pk->y, ndigits);
+ ret = ecc_is_pubkey_valid_partial(curve, pk);
+ if (ret)
+ goto err_alloc_product;
+
+ ecc_swap_digits(private_key, priv, ndigits);
+
product = ecc_alloc_point(ndigits);
if (!product) {
ret = -ENOMEM;
goto err_alloc_product;
}
- ecc_swap_digits(public_key, pk->x, ndigits);
- ecc_swap_digits(&public_key[ndigits], pk->y, ndigits);
- ecc_swap_digits(private_key, priv, ndigits);
-
ecc_point_mult(product, pk, priv, rand_z, curve->p, ndigits);
ecc_swap_digits(product->x, secret, ndigits);