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/**
* Client Key Exchange Message
* (C) 2004-2008 Jack Lloyd
*
* Released under the terms of the Botan license
*/
#include <botan/tls_messages.h>
#include <botan/dh.h>
#include <botan/rsa.h>
#include <botan/rng.h>
#include <botan/look_pk.h>
#include <botan/loadstor.h>
#include <memory>
namespace Botan {
/**
* Create a new Client Key Exchange message
*/
Client_Key_Exchange::Client_Key_Exchange(RandomNumberGenerator& rng,
Record_Writer& writer,
HandshakeHash& hash,
const Public_Key* pub_key,
Version_Code using_version,
Version_Code pref_version)
{
const DH_PublicKey* dh_pub = dynamic_cast<const DH_PublicKey*>(pub_key);
const RSA_PublicKey* rsa_pub = dynamic_cast<const RSA_PublicKey*>(pub_key);
include_length = true;
if(dh_pub)
{
DH_PrivateKey priv_key(rng, dh_pub->get_domain());
pre_master = priv_key.derive_key(dh_pub->get_y());
key_material = priv_key.public_value();
}
else if(rsa_pub)
{
pre_master.resize(48);
rng.randomize(pre_master, 48);
pre_master[0] = (pref_version >> 8) & 0xFF;
pre_master[1] = (pref_version ) & 0xFF;
std::auto_ptr<PK_Encryptor> encryptor(get_pk_encryptor(*rsa_pub,
"PKCS1v15"));
key_material = encryptor->encrypt(pre_master, rng);
if(using_version == SSL_V3)
include_length = false;
}
else
throw Invalid_Argument("Client_Key_Exchange: Key not RSA or DH");
send(writer, hash);
}
/**
* Read a Client Key Exchange message
*/
Client_Key_Exchange::Client_Key_Exchange(const MemoryRegion<byte>& contents,
const CipherSuite& suite,
Version_Code using_version)
{
include_length = true;
if(using_version == SSL_V3 &&
(suite.kex_type() == CipherSuite::NO_KEX ||
suite.kex_type() == CipherSuite::RSA_KEX))
include_length = false;
deserialize(contents);
}
/**
* Serialize a Client Key Exchange message
*/
SecureVector<byte> Client_Key_Exchange::serialize() const
{
SecureVector<byte> buf;
if(include_length)
{
u16bit key_size = key_material.size();
buf.append(get_byte(0, key_size));
buf.append(get_byte(1, key_size));
}
buf.append(key_material);
return buf;
}
/**
* Deserialize a Client Key Exchange message
*/
void Client_Key_Exchange::deserialize(const MemoryRegion<byte>& buf)
{
if(include_length)
{
if(buf.size() < 2)
throw Decoding_Error("Client_Key_Exchange: Packet corrupted");
u32bit size = make_u16bit(buf[0], buf[1]);
if(size + 2 != buf.size())
throw Decoding_Error("Client_Key_Exchange: Packet corrupted");
key_material.set(buf + 2, size);
}
else
key_material = buf;
}
/**
* Return the pre_master_secret
*/
SecureVector<byte>
Client_Key_Exchange::pre_master_secret(RandomNumberGenerator& rng,
const Private_Key* priv_key,
Version_Code version)
{
const DH_PrivateKey* dh_priv = dynamic_cast<const DH_PrivateKey*>(priv_key);
const RSA_PrivateKey* rsa_priv =
dynamic_cast<const RSA_PrivateKey*>(priv_key);
if(dh_priv)
{
try {
pre_master = dh_priv->derive_key(key_material, key_material.size());
}
catch(std::exception& e)
{
pre_master.resize(dh_priv->public_value().size());
rng.randomize(pre_master, pre_master.size());
}
return pre_master;
}
else if(rsa_priv)
{
std::auto_ptr<PK_Decryptor> decryptor(get_pk_decryptor(*rsa_priv,
"PKCS1v15"));
try {
pre_master = decryptor->decrypt(key_material);
if(pre_master.size() != 48 ||
make_u16bit(pre_master[0], pre_master[1]) != version)
throw Decoding_Error("Client_Key_Exchange: Secret corrupted");
}
catch(std::exception)
{
pre_master.resize(48);
rng.randomize(pre_master, pre_master.size());
pre_master[0] = (version >> 8) & 0xFF;
pre_master[1] = (version ) & 0xFF;
}
return pre_master;
}
else
throw Invalid_Argument("Client_Key_Exchange: Bad key for decrypt");
}
/**
* Return the pre_master_secret
*/
SecureVector<byte> Client_Key_Exchange::pre_master_secret() const
{
return pre_master;
}
}
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