21 files changed, 221 insertions, 282 deletions

diff --git a/src/engine/def_engine/def_pk_ops.cpp b/src/engine/def_engine/def_pk_ops.cpp
index e1040142e..b2f53376d 100644
--- a/src/engine/def_engine/def_pk_ops.cpp
+++ b/src/engine/def_engine/def_pk_ops.cpp
@@ -24,11 +24,31 @@
 #endif
 
 #if defined(BOTAN_HAS_DIFFIE_HELLMAN)
-  #include <botan/dh_op.h>
+  #include <botan/dh.h>
+#endif
+
+#if defined(BOTAN_HAS_ECDH)
+  #include <botan/ecdh.h>
 #endif
 
 namespace Botan {
 
+PK_Ops::KA_Operation*
+Default_Engine::get_key_agreement_op(const Private_Key& key) const
+   {
+#if defined(BOTAN_HAS_DIFFIE_HELLMAN)
+   if(const DH_PrivateKey* dh = dynamic_cast<const DH_PrivateKey*>(&key))
+      return new DH_KA_Operation(*dh);
+#endif
+
+#if defined(BOTAN_HAS_ECDH)
+   if(const ECDH_PrivateKey* ecdh = dynamic_cast<const ECDH_PrivateKey*>(&key))
+      return new ECDH_KA_Operation(*ecdh);
+#endif
+
+   return 0;
+   }
+
 #if defined(BOTAN_HAS_IF_PUBLIC_KEY_FAMILY)
 /*
 * Acquire an IF op
@@ -75,15 +95,4 @@ ELG_Operation* Default_Engine::elg_op(const DL_Group& group, const BigInt& y,
    }
 #endif
 
-#if defined(BOTAN_HAS_DIFFIE_HELLMAN)
-/*
-* Acquire a DH op
-*/
-DH_Operation* Default_Engine::dh_op(const DL_Group& group,
-                                    const BigInt& x) const
-   {
-   return new Default_DH_Op(group, x);
-   }
-#endif
-
 }
diff --git a/src/engine/def_engine/default_engine.h b/src/engine/def_engine/default_engine.h
index aa753fadb..918a42114 100644
--- a/src/engine/def_engine/default_engine.h
+++ b/src/engine/def_engine/default_engine.h
@@ -20,6 +20,8 @@ class Default_Engine : public Engine
    public:
       std::string provider_name() const { return "core"; }
 
+      PK_Ops::KA_Operation* get_key_agreement_op(const Private_Key&) const;
+
 #if defined(BOTAN_HAS_IF_PUBLIC_KEY_FAMILY)
       IF_Operation* if_op(const BigInt&, const BigInt&, const BigInt&,
                           const BigInt&, const BigInt&, const BigInt&,
@@ -40,10 +42,6 @@ class Default_Engine : public Engine
                             const BigInt&) const;
 #endif
 
-#if defined(BOTAN_HAS_DIFFIE_HELLMAN)
-      DH_Operation* dh_op(const DL_Group&, const BigInt&) const;
-#endif
-
       Modular_Exponentiator* mod_exp(const BigInt&,
                                      Power_Mod::Usage_Hints) const;
 
diff --git a/src/engine/engine.h b/src/engine/engine.h
index ba5f95c27..ea9c05997 100644
--- a/src/engine/engine.h
+++ b/src/engine/engine.h
@@ -15,6 +15,8 @@
 #include <botan/hash.h>
 #include <botan/mac.h>
 #include <botan/pow_mod.h>
+#include <botan/pk_keys.h>
+#include <botan/pk_ops.h>
 
 #include <utility>
 #include <map>
@@ -27,10 +29,6 @@
   #include <botan/dsa_op.h>
 #endif
 
-#if defined(BOTAN_HAS_DIFFIE_HELLMAN)
-  #include <botan/dh_op.h>
-#endif
-
 #if defined(BOTAN_HAS_NYBERG_RUEPPEL)
   #include <botan/nr_op.h>
 #endif
@@ -80,6 +78,12 @@ class BOTAN_DLL Engine
                                        Algorithm_Factory&)
          { return 0; }
 
+      virtual PK_Ops::KA_Operation*
+         get_key_agreement_op(const Private_Key&) const
+         {
+         return 0;
+         }
+
 #if defined(BOTAN_HAS_IF_PUBLIC_KEY_FAMILY)
       virtual IF_Operation* if_op(const BigInt&, const BigInt&, const BigInt&,
                                   const BigInt&, const BigInt&, const BigInt&,
@@ -104,11 +108,6 @@ class BOTAN_DLL Engine
                                     const BigInt&) const
          { return 0; }
 #endif
-
-#if defined(BOTAN_HAS_DIFFIE_HELLMAN)
-      virtual DH_Operation* dh_op(const DL_Group&, const BigInt&) const
-         { return 0; }
-#endif
    };
 
 }
diff --git a/src/engine/info.txt b/src/engine/info.txt
index b270edaa5..32fcf21c2 100644
--- a/src/engine/info.txt
+++ b/src/engine/info.txt
@@ -10,5 +10,6 @@ hash
 libstate
 mac
 numbertheory
+pubkey
 stream
 </requires>
diff --git a/src/libstate/pk_engine.cpp b/src/libstate/pk_engine.cpp
index ac2fa68b0..51aaa073e 100644
--- a/src/libstate/pk_engine.cpp
+++ b/src/libstate/pk_engine.cpp
@@ -91,25 +91,6 @@ ELG_Operation* elg_op(const DL_Group& group, const BigInt& y, const BigInt& x)
    }
 #endif
 
-#if defined(BOTAN_HAS_DIFFIE_HELLMAN)
-/*
-* Acquire a DH op
-*/
-DH_Operation* dh_op(const DL_Group& group, const BigInt& x)
-   {
-   Algorithm_Factory::Engine_Iterator i(global_state().algorithm_factory());
-
-   while(const Engine* engine = i.next())
-      {
-      DH_Operation* op = engine->dh_op(group, x);
-      if(op)
-         return op;
-      }
-
-   throw Lookup_Error("Engine_Core::dh_op: Unable to find a working engine");
-   }
-#endif
-
 /*
 * Acquire a modular exponentiator
 */
diff --git a/src/libstate/pk_engine.h b/src/libstate/pk_engine.h
index 25f326ef0..e6399058e 100644
--- a/src/libstate/pk_engine.h
+++ b/src/libstate/pk_engine.h
@@ -19,10 +19,6 @@
   #include <botan/dsa_op.h>
 #endif
 
-#if defined(BOTAN_HAS_DIFFIE_HELLMAN)
-  #include <botan/dh_op.h>
-#endif
-
 #if defined(BOTAN_HAS_NYBERG_RUEPPEL)
   #include <botan/nr_op.h>
 #endif
@@ -62,10 +58,6 @@ NR_Operation* nr_op(const DL_Group&, const BigInt&, const BigInt&);
 ELG_Operation* elg_op(const DL_Group&, const BigInt&, const BigInt&);
 #endif
 
-#if defined(BOTAN_HAS_DIFFIE_HELLMAN)
-DH_Operation* dh_op(const DL_Group&, const BigInt&);
-#endif
-
 }
 
 }
diff --git a/src/pubkey/dh/dh.cpp b/src/pubkey/dh/dh.cpp
index 4ebe1fa1c..70791fee4 100644
--- a/src/pubkey/dh/dh.cpp
+++ b/src/pubkey/dh/dh.cpp
@@ -21,14 +21,6 @@ DH_PublicKey::DH_PublicKey(const DL_Group& grp, const BigInt& y1)
    }
 
 /*
-* Return the maximum input size in bits
-*/
-u32bit DH_PublicKey::max_input_bits() const
-   {
-   return group_p().bits();
-   }
-
-/*
 * Return the public value for key agreement
 */
 MemoryVector<byte> DH_PublicKey::public_value() const
@@ -55,8 +47,6 @@ DH_PrivateKey::DH_PrivateKey(RandomNumberGenerator& rng,
    if(y == 0)
       y = power_mod(group_g(), x, group_p());
 
-   core = DH_Core(rng, group, x);
-
    if(x == 0)
       gen_check(rng);
    else
@@ -74,8 +64,6 @@ DH_PrivateKey::DH_PrivateKey(const AlgorithmIdentifier& alg_id,
    if(y == 0)
       y = power_mod(group_g(), x, group_p());
 
-   core = DH_Core(rng, group, x);
-
    load_check(rng);
    }
 
@@ -87,32 +75,4 @@ MemoryVector<byte> DH_PrivateKey::public_value() const
    return DH_PublicKey::public_value();
    }
 
-/*
-* Derive a key
-*/
-SecureVector<byte> DH_PrivateKey::derive_key(const byte w[],
-                                             u32bit w_len) const
-   {
-   return derive_key(BigInt::decode(w, w_len));
-   }
-
-/*
-* Derive a key
-*/
-SecureVector<byte> DH_PrivateKey::derive_key(const DH_PublicKey& key) const
-   {
-   return derive_key(key.get_y());
-   }
-
-/*
-* Derive a key
-*/
-SecureVector<byte> DH_PrivateKey::derive_key(const BigInt& w) const
-   {
-   const BigInt& p = group_p();
-   if(w <= 1 || w >= p-1)
-      throw Invalid_Argument(algo_name() + "::derive_key: Invalid key input");
-   return BigInt::encode_1363(core.agree(w), p.bytes());
-   }
-
 }
diff --git a/src/pubkey/dh/dh.h b/src/pubkey/dh/dh.h
index 14bc916a7..318a6215c 100644
--- a/src/pubkey/dh/dh.h
+++ b/src/pubkey/dh/dh.h
@@ -9,7 +9,8 @@
 #define BOTAN_DIFFIE_HELLMAN_H__
 
 #include <botan/dl_algo.h>
-#include <botan/dh_core.h>
+#include <botan/pow_mod.h>
+#include <botan/pk_ops.h>
 
 namespace Botan {
 
@@ -22,7 +23,7 @@ class BOTAN_DLL DH_PublicKey : public virtual DL_Scheme_PublicKey
       std::string algo_name() const { return "DH"; }
 
       MemoryVector<byte> public_value() const;
-      u32bit max_input_bits() const;
+      u32bit max_input_bits() const { return group_p().bits(); }
 
       DL_Group::Format group_format() const { return DL_Group::ANSI_X9_42; }
 
@@ -48,10 +49,6 @@ class BOTAN_DLL DH_PrivateKey : public DH_PublicKey,
                                 public virtual DL_Scheme_PrivateKey
    {
    public:
-      SecureVector<byte> derive_key(const byte other[], u32bit length) const;
-      SecureVector<byte> derive_key(const DH_PublicKey& other) const;
-      SecureVector<byte> derive_key(const BigInt& other) const;
-
       MemoryVector<byte> public_value() const;
 
       /**
@@ -72,8 +69,30 @@ class BOTAN_DLL DH_PrivateKey : public DH_PublicKey,
       */
       DH_PrivateKey(RandomNumberGenerator& rng, const DL_Group& grp,
                     const BigInt& x = 0);
+   };
+
+/**
+* DH operation
+*/
+class BOTAN_DLL DH_KA_Operation : public PK_Ops::KA_Operation
+   {
+   public:
+
+      DH_KA_Operation(const DH_PrivateKey& key) :
+         powermod_x_p(key.get_x(), key.get_domain().get_p()),
+         p_bytes(key.get_domain().get_p().bytes())
+         {}
+
+      SecureVector<byte> agree(const byte w[], u32bit w_len) const
+         {
+         return BigInt::encode_1363(
+            powermod_x_p(BigInt::decode(w, w_len)),
+            p_bytes);
+         }
+
    private:
-      DH_Core core;
+      Fixed_Exponent_Power_Mod powermod_x_p;
+      u32bit p_bytes;
    };
 
 }
diff --git a/src/pubkey/dh/dh_core.cpp b/src/pubkey/dh/dh_core.cpp
deleted file mode 100644
index cbe2dc9f1..000000000
--- a/src/pubkey/dh/dh_core.cpp
+++ /dev/null
@@ -1,65 +0,0 @@
-/*
-* PK Algorithm Core
-* (C) 1999-2007 Jack Lloyd
-*
-* Distributed under the terms of the Botan license
-*/
-
-#include <botan/dh_core.h>
-#include <botan/numthry.h>
-#include <botan/internal/pk_engine.h>
-#include <botan/parsing.h>
-#include <algorithm>
-
-namespace Botan {
-
-/*
-* DH_Core Constructor
-*/
-DH_Core::DH_Core(RandomNumberGenerator& rng,
-                 const DL_Group& group, const BigInt& x)
-   {
-   const u32bit BLINDING_BITS = BOTAN_PRIVATE_KEY_OP_BLINDING_BITS;
-
-   op = Engine_Core::dh_op(group, x);
-
-   const BigInt& p = group.get_p();
-
-   BigInt k(rng, std::min(p.bits()-1, BLINDING_BITS));
-
-   if(k != 0)
-      blinder = Blinder(k, power_mod(inverse_mod(k, p), x, p), p);
-   }
-
-/*
-* DH_Core Copy Constructor
-*/
-DH_Core::DH_Core(const DH_Core& core)
-   {
-   op = 0;
-   if(core.op)
-      op = core.op->clone();
-   blinder = core.blinder;
-   }
-
-/*
-* DH_Core Assignment Operator
-*/
-DH_Core& DH_Core::operator=(const DH_Core& core)
-   {
-   delete op;
-   if(core.op)
-      op = core.op->clone();
-   blinder = core.blinder;
-   return (*this);
-   }
-
-/*
-* DH Operation
-*/
-BigInt DH_Core::agree(const BigInt& i) const
-   {
-   return blinder.unblind(op->agree(blinder.blind(i)));
-   }
-
-}
diff --git a/src/pubkey/dh/dh_core.h b/src/pubkey/dh/dh_core.h
deleted file mode 100644
index 91b50a27a..000000000
--- a/src/pubkey/dh/dh_core.h
+++ /dev/null
@@ -1,38 +0,0 @@
-/*
-* DH Core
-* (C) 1999-2007 Jack Lloyd
-*
-* Distributed under the terms of the Botan license
-*/
-
-#ifndef BOTAN_DH_CORE_H__
-#define BOTAN_DH_CORE_H__
-
-#include <botan/dh_op.h>
-#include <botan/blinding.h>
-
-namespace Botan {
-
-/*
-* DH Core
-*/
-class BOTAN_DLL DH_Core
-   {
-   public:
-      BigInt agree(const BigInt&) const;
-
-      DH_Core& operator=(const DH_Core&);
-
-      DH_Core() { op = 0; }
-      DH_Core(const DH_Core&);
-      DH_Core(RandomNumberGenerator& rng,
-              const DL_Group&, const BigInt&);
-      ~DH_Core() { delete op; }
-   private:
-      DH_Operation* op;
-      Blinder blinder;
-   };
-
-}
-
-#endif
diff --git a/src/pubkey/dh/dh_op.h b/src/pubkey/dh/dh_op.h
deleted file mode 100644
index 50f3d7825..000000000
--- a/src/pubkey/dh/dh_op.h
+++ /dev/null
@@ -1,45 +0,0 @@
-/*
-* DH Operations
-* (C) 1999-2008 Jack Lloyd
-*
-* Distributed under the terms of the Botan license
-*/
-
-#ifndef BOTAN_DH_OPS_H__
-#define BOTAN_DH_OPS_H__
-
-#include <botan/dl_group.h>
-#include <botan/reducer.h>
-#include <botan/pow_mod.h>
-
-namespace Botan {
-
-/*
-* DH Operation Interface
-*/
-class BOTAN_DLL DH_Operation
-   {
-   public:
-      virtual BigInt agree(const BigInt&) const = 0;
-      virtual DH_Operation* clone() const = 0;
-      virtual ~DH_Operation() {}
-   };
-
-/*
-* Botan's Default DH Operation
-*/
-class BOTAN_DLL Default_DH_Op : public DH_Operation
-   {
-   public:
-      BigInt agree(const BigInt& i) const { return powermod_x_p(i); }
-      DH_Operation* clone() const { return new Default_DH_Op(*this); }
-
-      Default_DH_Op(const DL_Group& group, const BigInt& x) :
-         powermod_x_p(x, group.get_p()) {}
-   private:
-      Fixed_Exponent_Power_Mod powermod_x_p;
-   };
-
-}
-
-#endif
diff --git a/src/pubkey/dh/info.txt b/src/pubkey/dh/info.txt
index ca8f74fa1..e1e460cd0 100644
--- a/src/pubkey/dh/info.txt
+++ b/src/pubkey/dh/info.txt
@@ -1,14 +1,11 @@
 define DIFFIE_HELLMAN
 
 <header:public>
-dh_core.h
-dh_op.h
 dh.h
 </header:public>
 
 <source>
 dh.cpp
-dh_core.cpp
 </source>
 
 <requires>
diff --git a/src/pubkey/dlies/dlies.cpp b/src/pubkey/dlies/dlies.cpp
index 6ef3292e1..2253f84d5 100644
--- a/src/pubkey/dlies/dlies.cpp
+++ b/src/pubkey/dlies/dlies.cpp
@@ -14,16 +14,21 @@ namespace Botan {
 /*
 * DLIES_Encryptor Constructor
 */
-DLIES_Encryptor::DLIES_Encryptor(const PK_Key_Agreement_Key& k,
+DLIES_Encryptor::DLIES_Encryptor(const PK_Key_Agreement_Key& key,
                                  KDF* kdf_obj,
                                  MessageAuthenticationCode* mac_obj,
                                  u32bit mac_kl) :
-   key(k), kdf(kdf_obj), mac(mac_obj), mac_keylen(mac_kl)
+   ka(get_pk_kas(key, "Raw")),
+   kdf(kdf_obj),
+   mac(mac_obj),
+   mac_keylen(mac_kl)
    {
+   my_key = key.public_value();
    }
 
 DLIES_Encryptor::~DLIES_Encryptor()
    {
+   delete ka;
    delete kdf;
    delete mac;
    }
@@ -39,19 +44,18 @@ SecureVector<byte> DLIES_Encryptor::enc(const byte in[], u32bit length,
    if(other_key.empty())
       throw Invalid_State("DLIES: The other key was never set");
 
-   MemoryVector<byte> v = key.public_value();
+   SecureVector<byte> out(my_key.size() + length + mac->OUTPUT_LENGTH);
+   out.copy(my_key, my_key.size());
+   out.copy(my_key.size(), in, length);
 
-   SecureVector<byte> out(v.size() + length + mac->OUTPUT_LENGTH);
-   out.copy(v, v.size());
-   out.copy(v.size(), in, length);
-
-   SecureVector<byte> vz(v, key.derive_key(other_key, other_key.size()));
+   SecureVector<byte> vz(my_key, ka->derive_key(0, other_key).bits_of());
 
    const u32bit K_LENGTH = length + mac_keylen;
    OctetString K = kdf->derive_key(K_LENGTH, vz, vz.size());
+
    if(K.length() != K_LENGTH)
       throw Encoding_Error("DLIES: KDF did not provide sufficient output");
-   byte* C = out + v.size();
+   byte* C = out + my_key.size();
 
    xor_buf(C, K.begin() + mac_keylen, length);
    mac->set_key(K.begin(), mac_keylen);
@@ -84,16 +88,21 @@ u32bit DLIES_Encryptor::maximum_input_size() const
 /*
 * DLIES_Decryptor Constructor
 */
-DLIES_Decryptor::DLIES_Decryptor(const PK_Key_Agreement_Key& k,
+DLIES_Decryptor::DLIES_Decryptor(const PK_Key_Agreement_Key& key,
                                  KDF* kdf_obj,
                                  MessageAuthenticationCode* mac_obj,
                                  u32bit mac_kl) :
-   key(k), kdf(kdf_obj), mac(mac_obj), mac_keylen(mac_kl)
+   ka(get_pk_kas(key, "Raw")),
+   kdf(kdf_obj),
+   mac(mac_obj),
+   mac_keylen(mac_kl)
    {
+   my_key = key.public_value();
    }
 
 DLIES_Decryptor::~DLIES_Decryptor()
    {
+   delete ka;
    delete kdf;
    delete mac;
    }
@@ -103,18 +112,16 @@ DLIES_Decryptor::~DLIES_Decryptor()
 */
 SecureVector<byte> DLIES_Decryptor::dec(const byte msg[], u32bit length) const
    {
-   const u32bit public_len = key.public_value().size();
-
-   if(length < public_len + mac->OUTPUT_LENGTH)
+   if(length < my_key.size() + mac->OUTPUT_LENGTH)
       throw Decoding_Error("DLIES decryption: ciphertext is too short");
 
-   const u32bit CIPHER_LEN = length - public_len - mac->OUTPUT_LENGTH;
+   const u32bit CIPHER_LEN = length - my_key.size() - mac->OUTPUT_LENGTH;
 
-   SecureVector<byte> v(msg, public_len);
-   SecureVector<byte> C(msg + public_len, CIPHER_LEN);
-   SecureVector<byte> T(msg + public_len + CIPHER_LEN, mac->OUTPUT_LENGTH);
+   SecureVector<byte> v(msg, my_key.size());
+   SecureVector<byte> C(msg + my_key.size(), CIPHER_LEN);
+   SecureVector<byte> T(msg + my_key.size() + CIPHER_LEN, mac->OUTPUT_LENGTH);
 
-   SecureVector<byte> vz(v, key.derive_key(v, v.size()));
+   SecureVector<byte> vz(v, ka->derive_key(0, v).bits_of());
 
    const u32bit K_LENGTH = C.size() + mac_keylen;
    OctetString K = kdf->derive_key(K_LENGTH, vz, vz.size());
diff --git a/src/pubkey/dlies/dlies.h b/src/pubkey/dlies/dlies.h
index 88a22b9de..e8b87a091 100644
--- a/src/pubkey/dlies/dlies.h
+++ b/src/pubkey/dlies/dlies.h
@@ -33,9 +33,9 @@ class BOTAN_DLL DLIES_Encryptor : public PK_Encryptor
                              RandomNumberGenerator&) const;
       u32bit maximum_input_size() const;
 
-      const PK_Key_Agreement_Key& key;
-      SecureVector<byte> other_key;
+      SecureVector<byte> other_key, my_key;
 
+      PK_Key_Agreement* ka;
       KDF* kdf;
       MessageAuthenticationCode* mac;
       u32bit mac_keylen;
@@ -57,8 +57,9 @@ class BOTAN_DLL DLIES_Decryptor : public PK_Decryptor
    private:
       SecureVector<byte> dec(const byte[], u32bit) const;
 
-      const PK_Key_Agreement_Key& key;
+      SecureVector<byte> my_key;
 
+      PK_Key_Agreement* ka;
       KDF* kdf;
       MessageAuthenticationCode* mac;
       u32bit mac_keylen;
diff --git a/src/pubkey/ecdh/ecdh.cpp b/src/pubkey/ecdh/ecdh.cpp
index 7ecc40ae4..37dc7c392 100644
--- a/src/pubkey/ecdh/ecdh.cpp
+++ b/src/pubkey/ecdh/ecdh.cpp
@@ -11,6 +11,27 @@
 
 namespace Botan {
 
+ECDH_KA_Operation::ECDH_KA_Operation(const ECDH_PrivateKey& key)
+   {
+   cofactor = key.domain().get_cofactor();
+
+   curve = key.domain().get_curve();
+
+   l_times_priv = inverse_mod(cofactor, key.domain().get_order()) *
+                  key.private_value();
+   }
+
+SecureVector<byte> ECDH_KA_Operation::agree(const byte w[], u32bit w_len) const
+   {
+   PointGFp point = OS2ECP(w, w_len, curve);
+
+   PointGFp S = (cofactor * point) * l_times_priv;
+   S.check_invariants();
+
+   return BigInt::encode_1363(S.get_affine_x(),
+                              curve.get_p().bytes());
+   }
+
 /**
 * Derive a key
 */
diff --git a/src/pubkey/ecdh/ecdh.h b/src/pubkey/ecdh/ecdh.h
index 8185e25f2..ad7efdc13 100644
--- a/src/pubkey/ecdh/ecdh.h
+++ b/src/pubkey/ecdh/ecdh.h
@@ -11,6 +11,7 @@
 #define BOTAN_ECDH_KEY_H__
 
 #include <botan/ecc_key.h>
+#include <botan/pk_ops.h>
 
 namespace Botan {
 
@@ -75,7 +76,7 @@ class BOTAN_DLL ECDH_PrivateKey : public ECDH_PublicKey,
 
       MemoryVector<byte> public_value() const
          { return EC2OSP(public_point(), PointGFp::UNCOMPRESSED); }
-
+   private:
       /**
       * Derive a shared key with the other parties public key.
       * @param key the other partys public key
@@ -96,6 +97,20 @@ class BOTAN_DLL ECDH_PrivateKey : public ECDH_PublicKey,
       SecureVector<byte> derive_key(const PointGFp& point) const;
    };
 
+/**
+* ECDH operation
+*/
+class BOTAN_DLL ECDH_KA_Operation : public PK_Ops::KA_Operation
+   {
+   public:
+      ECDH_KA_Operation(const ECDH_PrivateKey& key);
+
+      SecureVector<byte> agree(const byte w[], u32bit w_len) const;
+   private:
+      CurveGFp curve;
+      BigInt l_times_priv, cofactor;
+   };
+
 }
 
 #endif
diff --git a/src/pubkey/info.txt b/src/pubkey/info.txt
index 4d7105e9d..01378b856 100644
--- a/src/pubkey/info.txt
+++ b/src/pubkey/info.txt
@@ -12,6 +12,7 @@ x509_key.cpp
 
 <header:public>
 pk_keys.h
+pk_ops.h
 pkcs8.h
 pubkey.h
 pubkey_enums.h
diff --git a/src/pubkey/pk_keys.h b/src/pubkey/pk_keys.h
index 8015c1076..c37ce46a5 100644
--- a/src/pubkey/pk_keys.h
+++ b/src/pubkey/pk_keys.h
@@ -158,8 +158,8 @@ class BOTAN_DLL PK_Verifying_wo_MR_Key : public virtual Public_Key
 class BOTAN_DLL PK_Key_Agreement_Key : public virtual Private_Key
    {
    public:
-      virtual SecureVector<byte> derive_key(const byte[], u32bit) const = 0;
       virtual MemoryVector<byte> public_value() const = 0;
+
       virtual ~PK_Key_Agreement_Key() {}
    };
 
diff --git a/src/pubkey/pk_ops.h b/src/pubkey/pk_ops.h
new file mode 100644
index 000000000..2b9ac4366
--- /dev/null
+++ b/src/pubkey/pk_ops.h
@@ -0,0 +1,38 @@
+/*
+* PK Operation Types
+* (C) 2010 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_PK_OPERATIONS_H__
+#define BOTAN_PK_OPERATIONS_H__
+
+#include <botan/secmem.h>
+
+namespace Botan {
+
+namespace PK_Ops {
+
+/*
+* A generic Key Agreement Operation (eg DH or ECDH)
+*/
+class BOTAN_DLL KA_Operation
+   {
+   public:
+      /*
+      * Perform a key agreement operation
+      * @param w the other key value
+      * @param w_len the length of w in bytes
+      * @returns the agreed key
+      */
+      virtual SecureVector<byte> agree(const byte w[], u32bit w_len) const = 0;
+
+      virtual ~KA_Operation() {}
+   };
+
+}
+
+}
+
+#endif
diff --git a/src/pubkey/pubkey.cpp b/src/pubkey/pubkey.cpp
index feb33a361..6932caa34 100644
--- a/src/pubkey/pubkey.cpp
+++ b/src/pubkey/pubkey.cpp
@@ -1,6 +1,6 @@
 /*
 * Public Key Base
-* (C) 1999-2007 Jack Lloyd
+* (C) 1999-2010 Jack Lloyd
 *
 * Distributed under the terms of the Botan license
 */
@@ -10,6 +10,8 @@
 #include <botan/ber_dec.h>
 #include <botan/bigint.h>
 #include <botan/parsing.h>
+#include <botan/libstate.h>
+#include <botan/engine.h>
 #include <botan/internal/bit_ops.h>
 #include <memory>
 
@@ -356,21 +358,34 @@ bool PK_Verifier_wo_MR::validate_signature(const MemoryRegion<byte>& msg,
 /*
 * PK_Key_Agreement Constructor
 */
-PK_Key_Agreement::PK_Key_Agreement(const PK_Key_Agreement_Key& k,
+PK_Key_Agreement::PK_Key_Agreement(const PK_Key_Agreement_Key& key,
                                    KDF* kdf_obj) :
-   key(k), kdf(kdf_obj)
+   kdf(kdf_obj)
    {
+   Algorithm_Factory::Engine_Iterator i(global_state().algorithm_factory());
+
+   while(const Engine* engine = i.next())
+      {
+      op = engine->get_key_agreement_op(key);
+      if(op)
+         break;
+      }
+
+   if(op == 0)
+      throw Lookup_Error("PK_Key_Agreement: No working engine for " +
+                         key.algo_name());
    }
 
 SymmetricKey PK_Key_Agreement::derive_key(u32bit key_len, const byte in[],
                                           u32bit in_len, const byte params[],
                                           u32bit params_len) const
    {
-   OctetString z = key.derive_key(in, in_len);
+   SecureVector<byte> z = op->agree(in, in_len);
+
    if(!kdf)
       return z;
 
-   return kdf->derive_key(key_len, z.bits_of(), params, params_len);
+   return kdf->derive_key(key_len, z, params, params_len);
    }
 
 }
diff --git a/src/pubkey/pubkey.h b/src/pubkey/pubkey.h
index 6d48faa4f..4d6490919 100644
--- a/src/pubkey/pubkey.h
+++ b/src/pubkey/pubkey.h
@@ -1,6 +1,6 @@
 /*
 * Public Key Interface
-* (C) 1999-2007 Jack Lloyd
+* (C) 1999-2010 Jack Lloyd
 *
 * Distributed under the terms of the Botan license
 */
@@ -9,6 +9,7 @@
 #define BOTAN_PUBKEY_H__
 
 #include <botan/pk_keys.h>
+#include <botan/pk_ops.h>
 #include <botan/symkey.h>
 #include <botan/rng.h>
 #include <botan/eme.h>
@@ -284,6 +285,23 @@ class BOTAN_DLL PK_Key_Agreement
       * @param in the other parties key
       * @param in_len the length of in in bytes
       * @param params extra derivation params
+      * @param params_len the length of params in bytes
+      */
+      SymmetricKey derive_key(u32bit key_len,
+                              const MemoryRegion<byte>& in,
+                              const byte params[],
+                              u32bit params_len) const
+         {
+         return derive_key(key_len, &in[0], in.size(),
+                           params, params_len);
+         }
+
+      /*
+      * Perform Key Agreement Operation
+      * @param key_len the desired key output size
+      * @param in the other parties key
+      * @param in_len the length of in in bytes
+      * @param params extra derivation params
       */
       SymmetricKey derive_key(u32bit key_len,
                               const byte in[], u32bit in_len,
@@ -294,6 +312,21 @@ class BOTAN_DLL PK_Key_Agreement
                            params.length());
          }
 
+      /*
+      * Perform Key Agreement Operation
+      * @param key_len the desired key output size
+      * @param in the other parties key
+      * @param params extra derivation params
+      */
+      SymmetricKey derive_key(u32bit key_len,
+                              const MemoryRegion<byte>& in,
+                              const std::string& params = "") const
+         {
+         return derive_key(key_len, &in[0], in.size(),
+                           reinterpret_cast<const byte*>(params.data()),
+                           params.length());
+         }
+
       /**
       * Construct a PK Key Agreement.
       * @param key the key to use
@@ -301,12 +334,12 @@ class BOTAN_DLL PK_Key_Agreement
       */
       PK_Key_Agreement(const PK_Key_Agreement_Key& key, KDF* kdf = 0);
 
-      ~PK_Key_Agreement() { delete kdf; }
+      ~PK_Key_Agreement() { delete op; delete kdf; }
    private:
       PK_Key_Agreement(const PK_Key_Agreement_Key&);
       PK_Key_Agreement& operator=(const PK_Key_Agreement&);
 
-      const PK_Key_Agreement_Key& key;
+      PK_Ops::KA_Operation* op;
       KDF* kdf;
    };