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/*
* Hooks for application level policies on TLS connections
* (C) 2004-2006,2013 Jack Lloyd
*
* Released under the terms of the Botan license
*/
#ifndef BOTAN_TLS_POLICY_H__
#define BOTAN_TLS_POLICY_H__
#include <botan/tls_version.h>
#include <botan/tls_ciphersuite.h>
#include <botan/x509cert.h>
#include <botan/dl_group.h>
#include <vector>
namespace Botan {
namespace TLS {
/**
* TLS Policy Base Class
* Inherit and overload as desired to suit local policy concerns
*/
class BOTAN_DLL Policy
{
public:
/**
* Returns a list of ciphers we are willing to negotiate, in
* order of preference.
*/
virtual std::vector<std::string> allowed_ciphers() const;
/**
* Returns a list of hash algorithms we are willing to use for
* signatures, in order of preference.
*/
virtual std::vector<std::string> allowed_signature_hashes() const;
/**
* Returns a list of MAC algorithms we are willing to use.
*/
virtual std::vector<std::string> allowed_macs() const;
/**
* Returns a list of key exchange algorithms we are willing to
* use, in order of preference. Allowed values: DH, empty string
* (representing RSA using server certificate key)
*/
virtual std::vector<std::string> allowed_key_exchange_methods() const;
/**
* Returns a list of signature algorithms we are willing to
* use, in order of preference. Allowed values RSA and DSA.
*/
virtual std::vector<std::string> allowed_signature_methods() const;
/**
* Return list of ECC curves we are willing to use in order of preference
*/
virtual std::vector<std::string> allowed_ecc_curves() const;
/**
* Returns a list of compression algorithms we are willing to use,
* in order of preference. Allowed values any value of
* Compression_Method.
*
* @note Compression is not currently supported
*/
virtual std::vector<byte> compression() const;
/**
* Choose an elliptic curve to use
*/
virtual std::string choose_curve(const std::vector<std::string>& curve_names) const;
/**
* Attempt to negotiate the use of the heartbeat extension
*/
virtual bool negotiate_heartbeat_support() const;
/**
* Allow renegotiation even if the counterparty doesn't
* support the secure renegotiation extension.
*
* @warning Changing this to true exposes you to injected
* plaintext attacks. Read RFC 5746 for background.
*/
virtual bool allow_insecure_renegotiation() const { return false; }
/**
* Allow servers to initiate a new handshake
*/
virtual bool allow_server_initiated_renegotiation() const;
/**
* Return the group to use for ephemeral Diffie-Hellman key agreement
*/
virtual DL_Group dh_group() const;
/**
* Return the minimum DH group size we're willing to use
*/
virtual size_t minimum_dh_group_size() const;
/**
* If this function returns false, unknown SRP/PSK identifiers
* will be rejected with an unknown_psk_identifier alert as soon
* as the non-existence is identified. Otherwise, a false
* identifier value will be used and the protocol allowed to
* proceed, causing the handshake to eventually fail without
* revealing that the username does not exist on this system.
*/
virtual bool hide_unknown_users() const { return false; }
/**
* Return the allowed lifetime of a session ticket. If 0, session
* tickets do not expire until the session ticket key rolls over.
* Expired session tickets cannot be used to resume a session.
*/
virtual u32bit session_ticket_lifetime() const;
/**
* @return true if and only if we are willing to accept this version
* Default accepts TLS v1.0 and later.
* Override if you want to allow negotiating SSLv3 (*not recommended*)
* Override if you want to enable DTLS in your application.
*/
virtual bool acceptable_protocol_version(Protocol_Version version) const;
/**
* Returns the more recent protocol version we are willing to
* use, for either TLS or DTLS depending on datagram param.
* Shouldn't ever need to override this unless you want to allow
* a user to disable use of TLS v1.2 (which is *not recommended*)
*/
virtual Protocol_Version latest_supported_version(bool datagram) const;
/**
* When offering this version, should we send a fallback SCSV?
* Default returns true iff version is not the latest version the
* policy allows, exists to allow override in case of interop problems.
*/
virtual bool send_fallback_scsv(const Protocol_Version& version) const;
/**
* Allows policy to reject any ciphersuites which are undesirable
* for whatever reason without having to reimplement ciphersuite_list
*/
virtual bool acceptable_ciphersuite(const Ciphersuite& suite) const;
/**
* @return true if servers should choose the ciphersuite matching
* their highest preference, rather than the clients.
* Has no effect on client side.
*/
virtual bool server_uses_own_ciphersuite_preferences() const { return true; }
/**
* Return allowed ciphersuites, in order of preference
*/
virtual std::vector<u16bit> ciphersuite_list(Protocol_Version version,
bool have_srp) const;
virtual ~Policy() {}
};
/**
* NSA Suite B 128-bit security level (see @rfc 6460)
*/
class BOTAN_DLL NSA_Suite_B_128 : public Policy
{
public:
std::vector<std::string> allowed_ciphers() const override
{ return std::vector<std::string>({"AES-128/GCM"}); }
std::vector<std::string> allowed_signature_hashes() const override
{ return std::vector<std::string>({"SHA-256"}); }
std::vector<std::string> allowed_macs() const override
{ return std::vector<std::string>({"AEAD"}); }
std::vector<std::string> allowed_key_exchange_methods() const override
{ return std::vector<std::string>({"ECDH"}); }
std::vector<std::string> allowed_signature_methods() const override
{ return std::vector<std::string>({"ECDSA"}); }
std::vector<std::string> allowed_ecc_curves() const override
{ return std::vector<std::string>({"secp256r1"}); }
bool acceptable_protocol_version(Protocol_Version version) const override
{ return version == Protocol_Version::TLS_V12; }
};
/**
* Policy for DTLS. We require DTLS v1.2 and an AEAD mode
*/
class BOTAN_DLL Datagram_Policy : public Policy
{
public:
std::vector<std::string> allowed_macs() const override
{ return std::vector<std::string>({"AEAD"}); }
bool acceptable_protocol_version(Protocol_Version version) const override
{ return version == Protocol_Version::DTLS_V12; }
};
}
}
#endif
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