1 files changed, 36 insertions, 0 deletions
diff --git a/botan/src/pubkey/eckaeg/eckaeg_op.cpp b/botan/src/pubkey/eckaeg/eckaeg_op.cpp
new file mode 100644
index 0000000..0cb5c3d
--- /dev/null
+++ b/botan/src/pubkey/eckaeg/eckaeg_op.cpp
@@ -0,0 +1,36 @@
+/*
+* ECKAEG Operation
+* (C) 2007 FlexSecure GmbH
+*     2008 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/eckaeg_op.h>
+#include <botan/numthry.h>
+
+namespace Botan {
+
+Default_ECKAEG_Op::Default_ECKAEG_Op(const EC_Domain_Params& dom_pars,
+                                     const BigInt& priv_key,
+                                     const PointGFp& pub_key)
+   : m_dom_pars(dom_pars),
+     m_pub_key(pub_key),
+     m_priv_key(priv_key)
+   {
+   }
+
+SecureVector<byte> Default_ECKAEG_Op::agree(const PointGFp& i) const
+   {
+   BigInt cofactor(m_dom_pars.get_cofactor());
+   BigInt n = m_dom_pars.get_order();
+   BigInt l(inverse_mod(cofactor,n)); // l=h^-1 mod n
+   PointGFp Q(cofactor*i); // q = h*Pb
+   PointGFp S(Q);
+   BigInt group_order = m_dom_pars.get_cofactor() * n;
+   S.mult_this_secure((m_priv_key*l)%n, group_order, n-1);
+   S.check_invariants();
+   return FE2OSP(S.get_affine_x()); // fe2os(xs)
+   }
+
+}