/* * 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 #include #include #include #include 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 allowed_ciphers() const; /** * Returns a list of hash algorithms we are willing to use for * signatures, in order of preference. */ virtual std::vector allowed_signature_hashes() const; /** * Returns a list of MAC algorithms we are willing to use. */ virtual std::vector 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 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 allowed_signature_methods() const; /** * Return list of ECC curves we are willing to use in order of preference */ virtual std::vector 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 compression() const; /** * Choose an elliptic curve to use */ virtual std::string choose_curve(const std::vector& 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(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 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 allowed_ciphers() const override { return std::vector({"AES-128/GCM"}); } std::vector allowed_signature_hashes() const override { return std::vector({"SHA-256"}); } std::vector allowed_macs() const override { return std::vector({"AEAD"}); } std::vector allowed_key_exchange_methods() const override { return std::vector({"ECDH"}); } std::vector allowed_signature_methods() const override { return std::vector({"ECDSA"}); } std::vector allowed_ecc_curves() const override { return std::vector({"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 allowed_macs() const override { return std::vector({"AEAD"}); } bool acceptable_protocol_version(Protocol_Version version) const override { return version == Protocol_Version::DTLS_V12; } }; } } #endif