| From 54211caa2e0e5163aefef390daf88a971367a702 Mon Sep 17 00:00:00 2001 |
| From: Glenn Strauss <gstrauss@gluelogic.com> |
| Date: Tue, 4 Oct 2022 17:09:24 -0400 |
| Subject: [PATCH 6/7] dpp_pkex: EC point mul w/ value < prime |
| |
| crypto_ec_point_mul() with mbedtls requires point |
| be multiplied by a multiplicand with value < prime |
| |
| Signed-off-by: Glenn Strauss <gstrauss@gluelogic.com> |
| --- |
| src/common/dpp_crypto.c | 4 +++- |
| 1 file changed, 3 insertions(+), 1 deletion(-) |
| |
| --- a/src/common/dpp_crypto.c |
| +++ b/src/common/dpp_crypto.c |
| @@ -1588,7 +1588,9 @@ dpp_pkex_derive_Qr(const struct dpp_curv |
| Pr = crypto_ec_key_get_public_key(Pr_key); |
| Qr = crypto_ec_point_init(ec); |
| hash_bn = crypto_bignum_init_set(hash, curve->hash_len); |
| - if (!Pr || !Qr || !hash_bn || crypto_ec_point_mul(ec, Pr, hash_bn, Qr)) |
| + if (!Pr || !Qr || !hash_bn || |
| + crypto_bignum_mod(hash_bn, crypto_ec_get_prime(ec), hash_bn) || |
| + crypto_ec_point_mul(ec, Pr, hash_bn, Qr)) |
| goto fail; |
| |
| if (crypto_ec_point_is_at_infinity(ec, Qr)) { |