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/*
* Policies for TLS
* (C) 2004-2010,2012 Jack Lloyd
*
* Released under the terms of the Botan license
*/
#include <botan/tls_policy.h>
#include <botan/tls_suites.h>
#include <botan/tls_exceptn.h>
#include <botan/internal/stl_util.h>
namespace Botan {
std::vector<std::string> TLS_Policy::allowed_ciphers() const
{
std::vector<std::string> allowed;
allowed.push_back("AES-256");
allowed.push_back("AES-128");
allowed.push_back("TripleDES");
allowed.push_back("ARC4");
// Note that SEED is not included by default
return allowed;
}
std::vector<std::string> TLS_Policy::allowed_hashes() const
{
std::vector<std::string> allowed;
allowed.push_back("SHA-256");
allowed.push_back("SHA-1");
// Note that MD5 is not included by default
return allowed;
}
std::vector<std::string> TLS_Policy::allowed_key_exchange_methods() const
{
std::vector<std::string> allowed;
//allowed.push_back("ECDH");
//allowed.push_back("SRP");
allowed.push_back("DH");
allowed.push_back(""); // means RSA via server cert
return allowed;
}
std::vector<std::string> TLS_Policy::allowed_signature_methods() const
{
std::vector<std::string> allowed;
//allowed.push_back("ECDSA");
allowed.push_back("RSA");
allowed.push_back("DSA");
return allowed;
}
namespace {
class Ciphersuite_Preference_Ordering
{
public:
Ciphersuite_Preference_Ordering(const std::vector<std::string>& ciphers,
const std::vector<std::string>& hashes,
const std::vector<std::string>& kex,
const std::vector<std::string>& sigs) :
m_ciphers(ciphers), m_hashes(hashes), m_kex(kex), m_sigs(sigs) {}
bool operator()(const TLS_Ciphersuite& a, const TLS_Ciphersuite& b) const
{
if(a.kex_algo() != b.kex_algo())
{
for(size_t i = 0; i != m_kex.size(); ++i)
{
if(a.kex_algo() == m_kex[i])
return true;
if(b.kex_algo() == m_kex[i])
return false;
}
}
if(a.cipher_algo() != b.cipher_algo())
{
for(size_t i = 0; i != m_ciphers.size(); ++i)
{
if(a.cipher_algo() == m_ciphers[i])
return true;
if(b.cipher_algo() == m_ciphers[i])
return false;
}
}
if(a.sig_algo() != b.sig_algo())
{
for(size_t i = 0; i != m_sigs.size(); ++i)
{
if(a.sig_algo() == m_sigs[i])
return true;
if(b.sig_algo() == m_sigs[i])
return false;
}
}
if(a.mac_algo() != b.mac_algo())
{
for(size_t i = 0; i != m_hashes.size(); ++i)
{
if(a.mac_algo() == m_hashes[i])
return true;
if(b.mac_algo() == m_hashes[i])
return false;
}
}
return false; // equal (?!?)
}
private:
std::vector<std::string> m_ciphers, m_hashes, m_kex, m_sigs;
};
}
std::vector<u16bit> TLS_Policy::ciphersuite_list(bool have_srp) const
{
std::vector<std::string> ciphers = allowed_ciphers();
std::vector<std::string> hashes = allowed_hashes();
std::vector<std::string> kex = allowed_key_exchange_methods();
std::vector<std::string> sigs = allowed_signature_methods();
if(!have_srp)
{
std::vector<std::string>::iterator i = std::find(kex.begin(), kex.end(), "SRP");
if(i != kex.end())
kex.erase(i);
}
Ciphersuite_Preference_Ordering order(ciphers, hashes, kex, sigs);
std::map<TLS_Ciphersuite, u16bit, Ciphersuite_Preference_Ordering> ciphersuites(order);
// When in doubt use brute force :)
for(u32bit i = 0; i != 65536; ++i)
{
TLS_Ciphersuite suite = TLS_Ciphersuite::lookup_ciphersuite(i);
if(suite.cipher_keylen() == 0)
continue; // not a ciphersuite we know
if(value_exists(ciphers, suite.cipher_algo()) &&
value_exists(hashes, suite.mac_algo()) &&
value_exists(kex, suite.kex_algo()) &&
value_exists(sigs, suite.sig_algo()))
{
ciphersuites[suite] = i;
}
}
std::vector<u16bit> ciphersuite_codes;
for(std::map<TLS_Ciphersuite, u16bit, Ciphersuite_Preference_Ordering>::iterator i = ciphersuites.begin();
i != ciphersuites.end(); ++i)
{
ciphersuite_codes.push_back(i->second);
}
return ciphersuite_codes;
}
/*
* Return allowed compression algorithms
*/
std::vector<byte> TLS_Policy::compression() const
{
std::vector<byte> algs;
algs.push_back(NO_COMPRESSION);
return algs;
}
/*
* Choose which ciphersuite to use
*/
u16bit TLS_Policy::choose_suite(const std::vector<u16bit>& client_suites,
bool have_rsa,
bool have_dsa,
bool have_srp) const
{
for(size_t i = 0; i != client_suites.size(); ++i)
{
u16bit suite_id = client_suites[i];
TLS_Ciphersuite suite = TLS_Ciphersuite::lookup_ciphersuite(suite_id);
if(suite.cipher_keylen() == 0)
continue; // not a ciphersuite we know
if(!have_srp && suite.kex_algo() == "SRP")
continue;
if(suite.sig_algo() == "RSA" && have_rsa)
return suite_id;
else if(suite.sig_algo() == "DSA" && have_dsa)
return suite_id;
#if 0
else if(suite.sig_algo() == "") // anonymous server
return suite_id;
#endif
}
return 0;
}
/*
* Choose which compression algorithm to use
*/
byte TLS_Policy::choose_compression(const std::vector<byte>& c_comp) const
{
std::vector<byte> s_comp = compression();
for(size_t i = 0; i != s_comp.size(); ++i)
for(size_t j = 0; j != c_comp.size(); ++j)
if(s_comp[i] == c_comp[j])
return s_comp[i];
return NO_COMPRESSION;
}
}
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