| developer | efb40c1 | 2022-12-21 18:05:47 +0800 | [diff] [blame] | 1 | From 54211caa2e0e5163aefef390daf88a971367a702 Mon Sep 17 00:00:00 2001 |
| 2 | From: Glenn Strauss <gstrauss@gluelogic.com> |
| 3 | Date: Tue, 4 Oct 2022 17:09:24 -0400 |
| 4 | Subject: [PATCH 6/7] dpp_pkex: EC point mul w/ value < prime |
| 5 | |
| 6 | crypto_ec_point_mul() with mbedtls requires point |
| 7 | be multiplied by a multiplicand with value < prime |
| 8 | |
| 9 | Signed-off-by: Glenn Strauss <gstrauss@gluelogic.com> |
| 10 | --- |
| 11 | src/common/dpp_crypto.c | 4 +++- |
| 12 | 1 file changed, 3 insertions(+), 1 deletion(-) |
| 13 | |
| 14 | --- a/src/common/dpp_crypto.c |
| 15 | +++ b/src/common/dpp_crypto.c |
| 16 | @@ -1567,7 +1567,9 @@ dpp_pkex_derive_Qr(const struct dpp_curv |
| 17 | Pr = crypto_ec_key_get_public_key(Pr_key); |
| 18 | Qr = crypto_ec_point_init(ec); |
| 19 | hash_bn = crypto_bignum_init_set(hash, curve->hash_len); |
| 20 | - if (!Pr || !Qr || !hash_bn || crypto_ec_point_mul(ec, Pr, hash_bn, Qr)) |
| 21 | + if (!Pr || !Qr || !hash_bn || |
| 22 | + crypto_bignum_mod(hash_bn, crypto_ec_get_prime(ec), hash_bn) || |
| 23 | + crypto_ec_point_mul(ec, Pr, hash_bn, Qr)) |
| 24 | goto fail; |
| 25 | |
| 26 | if (crypto_ec_point_is_at_infinity(ec, Qr)) { |