3 files changed, 182 insertions, 0 deletions
diff --git a/src/pubkey/ecdh/ecdh.cpp b/src/pubkey/ecdh/ecdh.cpp
new file mode 100644
index 000000000..2ddc371b2
--- /dev/null
+++ b/src/pubkey/ecdh/ecdh.cpp
@@ -0,0 +1,72 @@
+/*
+* 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>
+
+#include <iostream>
+
+namespace Botan {
+
+ECDH_PublicKey::ECDH_PublicKey(const EC_Domain_Params& dom_par,
+                               const PointGFp& pub_point)
+   {
+   domain_params = dom_par;
+   public_key = pub_point;
+
+   if(domain().get_curve() != public_point().get_curve())
+      throw Invalid_Argument("ECDH_PublicKey: curve mismatch in constructor");
+   }
+
+ECDH_PrivateKey::ECDH_PrivateKey(RandomNumberGenerator& rng,
+                                 const EC_Domain_Params& dom_pars)
+   {
+   domain_params = dom_pars;
+   generate_private_key(rng);
+   }
+
+/**
+* Derive a key
+*/
+SecureVector<byte> ECDH_PrivateKey::derive_key(const byte key[],
+                                               u32bit key_len) const
+   {
+   MemoryVector<byte> key_x(key, key_len); // FIXME: nasty/slow
+   PointGFp point = OS2ECP(key_x, public_point().get_curve());
+
+   return derive_key(point);
+   }
+
+/**
+* Derive a key
+*/
+SecureVector<byte> ECDH_PrivateKey::derive_key(const ECDH_PublicKey& key) const
+   {
+   return derive_key(key.public_point());
+   }
+
+/**
+* Derive a key
+*/
+SecureVector<byte> ECDH_PrivateKey::derive_key(const PointGFp& point) const
+   {
+   const BigInt& cofactor = domain().get_cofactor();
+   const BigInt& n = domain().get_order();
+
+   BigInt l = inverse_mod(cofactor, n); // can precompute this
+
+   PointGFp S = (cofactor * point) * (private_value() * l);
+   S.check_invariants();
+
+   //PointGFp S = point * private_value();
+
+   return BigInt::encode_1363(S.get_affine_x(),
+                              point.get_curve().get_p().bytes());
+   }
+
+}
diff --git a/src/pubkey/ecdh/ecdh.h b/src/pubkey/ecdh/ecdh.h
new file mode 100644
index 000000000..632083dcc
--- /dev/null
+++ b/src/pubkey/ecdh/ecdh.h
@@ -0,0 +1,100 @@
+/*
+* ECDH
+* (C) 2007 Falko Strenzke, FlexSecure GmbH
+*          Manuel Hartl, FlexSecure GmbH
+* (C) 2008-2010 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_ECDH_KEY_H__
+#define BOTAN_ECDH_KEY_H__
+
+#include <botan/ecc_key.h>
+
+namespace Botan {
+
+/**
+* This class represents ECDH Public Keys.
+*/
+class BOTAN_DLL ECDH_PublicKey : public virtual EC_PublicKey
+   {
+   public:
+
+      /**
+      * Get this keys algorithm name.
+      * @result this keys algorithm name
+      */
+      std::string algo_name() const { return "ECDH"; }
+
+      /**
+      * Default constructor. Use this one if you want to later fill
+      * this object with data from an encoded key.
+      */
+      ECDH_PublicKey() {}
+
+      /**
+      * Construct a public key from a given public point.
+      * @param dom_par the domain parameters associated with this key
+      * @param public_point the public point defining this key
+      */
+      ECDH_PublicKey(const EC_Domain_Params& dom_par,
+                     const PointGFp& public_point);
+
+      /**
+      * Get the maximum number of bits allowed to be fed to this key.
+      * This is the bitlength of the order of the base point.
+
+      * @result the maximum number of input bits
+      */
+      u32bit max_input_bits() const { return domain().get_order().bits(); }
+   };
+
+/**
+* This class represents ECDH Private Keys.
+*/
+class BOTAN_DLL ECDH_PrivateKey : public ECDH_PublicKey,
+                                  public EC_PrivateKey,
+                                  public PK_Key_Agreement_Key
+   {
+   public:
+
+      /**
+      * Generate a new private key
+      * @param the domain parameters to used for this key
+      */
+      ECDH_PrivateKey(RandomNumberGenerator& rng,
+                      const EC_Domain_Params& dom_pars);
+
+      /**
+      * Default constructor. Use this one if you want to later fill
+      * this object with data from an encoded key.
+      */
+      ECDH_PrivateKey() {}
+
+      MemoryVector<byte> public_value() const
+         { return EC2OSP(public_point(), PointGFp::UNCOMPRESSED); }
+
+      /**
+      * Derive a shared key with the other parties public key.
+      * @param key the other partys public key
+      * @param key_len the other partys public key
+      */
+      SecureVector<byte> derive_key(const byte key[], u32bit key_len) const;
+
+      /**
+      * Derive a shared key with the other parties public key.
+      * @param other the other partys public key
+      */
+      SecureVector<byte> derive_key(const ECDH_PublicKey& other) const;
+
+      /**
+      * Derive a shared key with the other parties public key.
+      * @param point the public point of the other parties key
+      */
+      SecureVector<byte> derive_key(const PointGFp& point) const;
+   };
+
+}
+
+#endif
diff --git a/src/pubkey/ecdh/info.txt b/src/pubkey/ecdh/info.txt
new file mode 100644
index 000000000..12826c81b
--- /dev/null
+++ b/src/pubkey/ecdh/info.txt
@@ -0,0 +1,10 @@
+define ECDH
+
+<requires>
+alloc
+asn1
+ec_dompar
+ecc_key
+libstate
+numbertheory
+</requires>