1 files changed, 35 insertions, 0 deletions
diff --git a/lib/pubkey/ecdh/ecdh.cpp b/lib/pubkey/ecdh/ecdh.cpp
new file mode 100644
index 000000000..0f93a0f97
--- /dev/null
+++ b/lib/pubkey/ecdh/ecdh.cpp
@@ -0,0 +1,35 @@
+/*
+* ECDH implemenation
+* (C) 2007 Manuel Hartl, FlexSecure GmbH
+*     2007 Falko Strenzke, FlexSecure GmbH
+*     2008-2010 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/ecdh.h>
+
+namespace Botan {
+
+ECDH_KA_Operation::ECDH_KA_Operation(const ECDH_PrivateKey& key) :
+   curve(key.domain().get_curve()),
+   cofactor(key.domain().get_cofactor())
+   {
+   l_times_priv = inverse_mod(cofactor, key.domain().get_order()) *
+                  key.private_value();
+   }
+
+secure_vector<byte> ECDH_KA_Operation::agree(const byte w[], size_t w_len)
+   {
+   PointGFp point = OS2ECP(w, w_len, curve);
+
+   PointGFp S = (cofactor * point) * l_times_priv;
+
+   BOTAN_ASSERT(S.on_the_curve(),
+                "ECDH agreed value was on the curve");
+
+   return BigInt::encode_1363(S.get_affine_x(),
+                              curve.get_p().bytes());
+   }
+
+}