Remove the key() method on server key exchange - instead leave it to

the client key exchange object to interpret the message on the basis
of the chosen ciphersuite.

3 files changed, 18 insertions, 21 deletions

diff --git a/src/tls/c_kex.cpp b/src/tls/c_kex.cpp
index b2dd0b861..63ba6fcb7 100644
--- a/src/tls/c_kex.cpp
+++ b/src/tls/c_kex.cpp
@@ -48,21 +48,28 @@ Client_Key_Exchange::Client_Key_Exchange(Record_Writer& writer,
 
    if(state->server_kex)
       {
-      std::auto_ptr<Public_Key> pub_key(state->server_kex->key());
+      const std::vector<BigInt>& params = state->server_kex->params();
 
-      if(pub_key->algo_name() != state->suite.kex_algo())
-         throw TLS_Exception(HANDSHAKE_FAILURE,
-                             "Server sent a " + pub_key->algo_name() +
-                             " key but we expected " + state->suite.kex_algo());
-
-      if(const DH_PublicKey* dh_pub = dynamic_cast<const DH_PublicKey*>(pub_key.get()))
+      if(state->suite.kex_algo() == "DH")
          {
-         DH_PrivateKey priv_key(rng, dh_pub->get_domain());
+         if(params.size() != 3)
+            throw Decoding_Error("Bad params size for DH key exchange");
+
+         DL_Group group(params[0], params[1]);
+
+         if(!group.verify_group(rng, true))
+            throw Internal_Error("DH group failed validation, possible attack");
+
+         DH_PublicKey counterparty_key(group, params[2]);
+
+         // FIXME Check that public key is residue?
+
+         DH_PrivateKey priv_key(rng, group);
 
          PK_Key_Agreement ka(priv_key, "Raw");
 
          pre_master = strip_leading_zeros(
-            ka.derive_key(0, dh_pub->public_value()).bits_of());
+            ka.derive_key(0, counterparty_key.public_value()).bits_of());
 
          key_material = priv_key.public_value();
          }
diff --git a/src/tls/s_kex.cpp b/src/tls/s_kex.cpp
index 71e40f01c..bbad6fd83 100644
--- a/src/tls/s_kex.cpp
+++ b/src/tls/s_kex.cpp
@@ -118,17 +118,6 @@ Server_Key_Exchange::Server_Key_Exchange(const MemoryRegion<byte>& buf,
    }
 
 /**
-* Return the public key
-*/
-Public_Key* Server_Key_Exchange::key() const
-   {
-   if(m_params.size() == 3)
-      return new DH_PublicKey(DL_Group(m_params[0], m_params[1]), m_params[2]);
-   else
-      throw Internal_Error("Server_Key_Exchange::key: No key set");
-   }
-
-/**
 * Verify a Server Key Exchange message
 */
 bool Server_Key_Exchange::verify(const X509_Certificate& cert,
diff --git a/src/tls/tls_messages.h b/src/tls/tls_messages.h
index e58a3bfbf..3579f7828 100644
--- a/src/tls/tls_messages.h
+++ b/src/tls/tls_messages.h
@@ -356,7 +356,8 @@ class Server_Key_Exchange : public Handshake_Message
    {
    public:
       Handshake_Type type() const { return SERVER_KEX; }
-      Public_Key* key() const;
+
+      const std::vector<BigInt>& params() const { return m_params; }
 
       bool verify(const X509_Certificate& cert,
                   TLS_Handshake_State* state) const;