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/*
* TLS Session Key
* (C) 2004-2006,2011 Jack Lloyd
*
* Released under the terms of the Botan license
*/
#include <botan/internal/tls_session_key.h>
#include <botan/internal/tls_handshake_state.h>
#include <botan/internal/tls_messages.h>
#include <botan/lookup.h>
#include <memory>
namespace Botan {
namespace {
std::string lookup_prf_name(Version_Code version)
{
if(version == SSL_V3)
return "SSL3-PRF";
else if(version == TLS_V10 || version == TLS_V11)
return "TLS-PRF";
else if(version == TLS_V12)
return "TLS-12-PRF(SHA-256)";
else
throw Invalid_Argument("Session_Keys: Unknown version code");
}
}
/**
* Session_Keys Constructor
*/
Session_Keys::Session_Keys(TLS_Handshake_State* state,
const MemoryRegion<byte>& pre_master_secret,
bool resuming)
{
const std::string prf_name = lookup_prf_name(state->version);
const size_t mac_keylen = output_length_of(state->suite.mac_algo());
const size_t cipher_keylen = state->suite.cipher_keylen();
size_t cipher_ivlen = 0;
if(have_block_cipher(state->suite.cipher_algo()))
cipher_ivlen = block_size_of(state->suite.cipher_algo());
const size_t prf_gen = 2 * (mac_keylen + cipher_keylen + cipher_ivlen);
const byte MASTER_SECRET_MAGIC[] = {
0x6D, 0x61, 0x73, 0x74, 0x65, 0x72, 0x20, 0x73, 0x65, 0x63, 0x72, 0x65, 0x74 };
const byte KEY_GEN_MAGIC[] = {
0x6B, 0x65, 0x79, 0x20, 0x65, 0x78, 0x70, 0x61, 0x6E, 0x73, 0x69, 0x6F, 0x6E };
std::auto_ptr<KDF> prf(get_kdf(prf_name));
if(resuming)
{
master_sec = pre_master_secret;
}
else
{
SecureVector<byte> salt;
if(state->version != SSL_V3)
salt += std::make_pair(MASTER_SECRET_MAGIC, sizeof(MASTER_SECRET_MAGIC));
salt += state->client_hello->random();
salt += state->server_hello->random();
master_sec = prf->derive_key(48, pre_master_secret, salt);
}
SecureVector<byte> salt;
if(state->version != SSL_V3)
salt += std::make_pair(KEY_GEN_MAGIC, sizeof(KEY_GEN_MAGIC));
salt += state->server_hello->random();
salt += state->client_hello->random();
SymmetricKey keyblock = prf->derive_key(prf_gen, master_sec, salt);
const byte* key_data = keyblock.begin();
c_mac = SymmetricKey(key_data, mac_keylen);
key_data += mac_keylen;
s_mac = SymmetricKey(key_data, mac_keylen);
key_data += mac_keylen;
c_cipher = SymmetricKey(key_data, cipher_keylen);
key_data += cipher_keylen;
s_cipher = SymmetricKey(key_data, cipher_keylen);
key_data += cipher_keylen;
c_iv = InitializationVector(key_data, cipher_ivlen);
key_data += cipher_ivlen;
s_iv = InitializationVector(key_data, cipher_ivlen);
}
}
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