From: Dr. Stephen Henson <steve@openssl.org>
Date: Sat, 10 Dec 2011 13:35:11 +0000 (+0000)
Subject: add cofactor ECDH support from fips branch
X-Git-Tag: OpenSSL_1_0_2-beta1~218
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=3e792793f6bd74e3a753c1b104417ba2b162f4f5;p=oweals%2Fopenssl.git

add cofactor ECDH support from fips branch
(cherry picked from commit a3a2e3a43d13d8486c5e100e1bef7fec8e61b27b)
---

diff --git a/crypto/ecdh/ecdh.h b/crypto/ecdh/ecdh.h
index 98c6cdf9be..6d792180d6 100644
--- a/crypto/ecdh/ecdh.h
+++ b/crypto/ecdh/ecdh.h
@@ -85,6 +85,8 @@
 extern "C" {
 #endif
 
+#define EC_FLAG_COFACTOR_ECDH	0x1000
+
 const ECDH_METHOD *ECDH_OpenSSL(void);
 
 void	  ECDH_set_default_method(const ECDH_METHOD *);
diff --git a/crypto/ecdh/ech_ossl.c b/crypto/ecdh/ech_ossl.c
index 4a30628fbc..fa98eb11ce 100644
--- a/crypto/ecdh/ech_ossl.c
+++ b/crypto/ecdh/ech_ossl.c
@@ -137,6 +137,18 @@ static int ecdh_compute_key(void *out, size_t outlen, const EC_POINT *pub_key,
 		}
 
 	group = EC_KEY_get0_group(ecdh);
+
+	if (EC_KEY_get_flags(ecdh) & EC_FLAG_COFACTOR_ECDH)
+		{
+		if (!EC_GROUP_get_cofactor(group, x, ctx) ||
+			!BN_mul(x, x, priv_key, ctx))
+			{
+			ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
+			goto err;
+			}
+		priv_key = x;
+		}
+
 	if ((tmp=EC_POINT_new(group)) == NULL)
 		{
 		ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_MALLOC_FAILURE);