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diff --git a/src/main/java/org/bouncycastle/crypto/agreement/ECDHBasicAgreement.java b/src/main/java/org/bouncycastle/crypto/agreement/ECDHBasicAgreement.java
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+package org.bouncycastle.crypto.agreement;
+
+import java.math.BigInteger;
+
+import org.bouncycastle.math.ec.ECPoint;
+
+import org.bouncycastle.crypto.BasicAgreement;
+import org.bouncycastle.crypto.CipherParameters;
+import org.bouncycastle.crypto.params.ECPublicKeyParameters;
+import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
+
+/**
+ * P1363 7.2.1 ECSVDP-DH
+ *
+ * ECSVDP-DH is Elliptic Curve Secret Value Derivation Primitive,
+ * Diffie-Hellman version. It is based on the work of [DH76], [Mil86],
+ * and [Kob87]. This primitive derives a shared secret value from one
+ * party's private key and another party's public key, where both have
+ * the same set of EC domain parameters. If two parties correctly
+ * execute this primitive, they will produce the same output. This
+ * primitive can be invoked by a scheme to derive a shared secret key;
+ * specifically, it may be used with the schemes ECKAS-DH1 and
+ * DL/ECKAS-DH2. It assumes that the input keys are valid (see also
+ * Section 7.2.2).
+ */
+public class ECDHBasicAgreement
+    implements BasicAgreement
+{
+    private ECPrivateKeyParameters key;
+
+    public void init(
+        CipherParameters key)
+    {
+        this.key = (ECPrivateKeyParameters)key;
+    }
+
+    public BigInteger calculateAgreement(
+        CipherParameters pubKey)
+    {
+        ECPublicKeyParameters pub = (ECPublicKeyParameters)pubKey;
+        ECPoint P = pub.getQ().multiply(key.getD());
+
+        // if (p.isInfinity()) throw new RuntimeException("d*Q == infinity");
+
+        return P.getX().toBigInteger();
+    }
+}