diff options
Diffstat (limited to 'comm/third_party/botan/src/lib/tls/msg_client_kex.cpp')
| -rw-r--r-- | comm/third_party/botan/src/lib/tls/msg_client_kex.cpp | 404 |
1 files changed, 404 insertions, 0 deletions
diff --git a/comm/third_party/botan/src/lib/tls/msg_client_kex.cpp b/comm/third_party/botan/src/lib/tls/msg_client_kex.cpp new file mode 100644 index 0000000000..39266962b5 --- /dev/null +++ b/comm/third_party/botan/src/lib/tls/msg_client_kex.cpp @@ -0,0 +1,404 @@ +/* +* Client Key Exchange Message +* (C) 2004-2010,2016 Jack Lloyd +* 2017 Harry Reimann, Rohde & Schwarz Cybersecurity +* +* Botan is released under the Simplified BSD License (see license.txt) +*/ + +#include <botan/tls_messages.h> +#include <botan/tls_extensions.h> +#include <botan/rng.h> + +#include <botan/internal/tls_reader.h> +#include <botan/internal/tls_handshake_io.h> +#include <botan/internal/tls_handshake_state.h> +#include <botan/internal/tls_handshake_hash.h> +#include <botan/credentials_manager.h> +#include <botan/internal/ct_utils.h> + +#include <botan/rsa.h> + +#if defined(BOTAN_HAS_CECPQ1) + #include <botan/cecpq1.h> +#endif + +#if defined(BOTAN_HAS_SRP6) + #include <botan/srp6.h> +#endif + +namespace Botan { + +namespace TLS { + +/* +* Create a new Client Key Exchange message +*/ +Client_Key_Exchange::Client_Key_Exchange(Handshake_IO& io, + Handshake_State& state, + const Policy& policy, + Credentials_Manager& creds, + const Public_Key* server_public_key, + const std::string& hostname, + RandomNumberGenerator& rng) + { + const Kex_Algo kex_algo = state.ciphersuite().kex_method(); + + if(kex_algo == Kex_Algo::PSK) + { + std::string identity_hint = ""; + + if(state.server_kex()) + { + TLS_Data_Reader reader("ClientKeyExchange", state.server_kex()->params()); + identity_hint = reader.get_string(2, 0, 65535); + } + + const std::string psk_identity = + creds.psk_identity("tls-client", hostname, identity_hint); + + append_tls_length_value(m_key_material, psk_identity, 2); + + SymmetricKey psk = creds.psk("tls-client", hostname, psk_identity); + + std::vector<uint8_t> zeros(psk.length()); + + append_tls_length_value(m_pre_master, zeros, 2); + append_tls_length_value(m_pre_master, psk.bits_of(), 2); + } + else if(state.server_kex()) + { + TLS_Data_Reader reader("ClientKeyExchange", state.server_kex()->params()); + + SymmetricKey psk; + + if(kex_algo == Kex_Algo::DHE_PSK || + kex_algo == Kex_Algo::ECDHE_PSK) + { + std::string identity_hint = reader.get_string(2, 0, 65535); + + const std::string psk_identity = + creds.psk_identity("tls-client", hostname, identity_hint); + + append_tls_length_value(m_key_material, psk_identity, 2); + + psk = creds.psk("tls-client", hostname, psk_identity); + } + + if(kex_algo == Kex_Algo::DH || + kex_algo == Kex_Algo::DHE_PSK) + { + const std::vector<uint8_t> modulus = reader.get_range<uint8_t>(2, 1, 65535); + const std::vector<uint8_t> generator = reader.get_range<uint8_t>(2, 1, 65535); + const std::vector<uint8_t> peer_public_value = reader.get_range<uint8_t>(2, 1, 65535); + + if(reader.remaining_bytes()) + throw Decoding_Error("Bad params size for DH key exchange"); + + const std::pair<secure_vector<uint8_t>, std::vector<uint8_t>> dh_result = + state.callbacks().tls_dh_agree(modulus, generator, peer_public_value, policy, rng); + + if(kex_algo == Kex_Algo::DH) + m_pre_master = dh_result.first; + else + { + append_tls_length_value(m_pre_master, dh_result.first, 2); + append_tls_length_value(m_pre_master, psk.bits_of(), 2); + } + + append_tls_length_value(m_key_material, dh_result.second, 2); + } + else if(kex_algo == Kex_Algo::ECDH || + kex_algo == Kex_Algo::ECDHE_PSK) + { + const uint8_t curve_type = reader.get_byte(); + if(curve_type != 3) + throw Decoding_Error("Server sent non-named ECC curve"); + + const Group_Params curve_id = static_cast<Group_Params>(reader.get_uint16_t()); + const std::vector<uint8_t> peer_public_value = reader.get_range<uint8_t>(1, 1, 255); + + if(policy.choose_key_exchange_group({curve_id}) != curve_id) + { + throw TLS_Exception(Alert::HANDSHAKE_FAILURE, + "Server sent ECC curve prohibited by policy"); + } + + const std::string curve_name = state.callbacks().tls_decode_group_param(curve_id); + + if(curve_name == "") + throw Decoding_Error("Server sent unknown named curve " + + std::to_string(static_cast<uint16_t>(curve_id))); + + const std::pair<secure_vector<uint8_t>, std::vector<uint8_t>> ecdh_result = + state.callbacks().tls_ecdh_agree(curve_name, peer_public_value, policy, rng, + state.server_hello()->prefers_compressed_ec_points()); + + if(kex_algo == Kex_Algo::ECDH) + { + m_pre_master = ecdh_result.first; + } + else + { + append_tls_length_value(m_pre_master, ecdh_result.first, 2); + append_tls_length_value(m_pre_master, psk.bits_of(), 2); + } + + append_tls_length_value(m_key_material, ecdh_result.second, 1); + } +#if defined(BOTAN_HAS_SRP6) + else if(kex_algo == Kex_Algo::SRP_SHA) + { + const BigInt N = BigInt::decode(reader.get_range<uint8_t>(2, 1, 65535)); + const BigInt g = BigInt::decode(reader.get_range<uint8_t>(2, 1, 65535)); + std::vector<uint8_t> salt = reader.get_range<uint8_t>(1, 1, 255); + const BigInt B = BigInt::decode(reader.get_range<uint8_t>(2, 1, 65535)); + + const std::string srp_group = srp6_group_identifier(N, g); + + const std::string srp_identifier = + creds.srp_identifier("tls-client", hostname); + + const std::string srp_password = + creds.srp_password("tls-client", hostname, srp_identifier); + + std::pair<BigInt, SymmetricKey> srp_vals = + srp6_client_agree(srp_identifier, + srp_password, + srp_group, + "SHA-1", + salt, + B, + rng); + + append_tls_length_value(m_key_material, BigInt::encode(srp_vals.first), 2); + m_pre_master = srp_vals.second.bits_of(); + } +#endif + +#if defined(BOTAN_HAS_CECPQ1) + else if(kex_algo == Kex_Algo::CECPQ1) + { + const std::vector<uint8_t> cecpq1_offer = reader.get_range<uint8_t>(2, 1, 65535); + + if(cecpq1_offer.size() != CECPQ1_OFFER_BYTES) + throw TLS_Exception(Alert::HANDSHAKE_FAILURE, "Invalid CECPQ1 key size"); + + std::vector<uint8_t> newhope_accept(CECPQ1_ACCEPT_BYTES); + secure_vector<uint8_t> shared_secret(CECPQ1_SHARED_KEY_BYTES); + CECPQ1_accept(shared_secret.data(), newhope_accept.data(), cecpq1_offer.data(), rng); + append_tls_length_value(m_key_material, newhope_accept, 2); + m_pre_master = shared_secret; + } +#endif + else + { + throw Internal_Error("Client_Key_Exchange: Unknown key exchange method was negotiated"); + } + + reader.assert_done(); + } + else + { + // No server key exchange msg better mean RSA kex + RSA key in cert + + if(kex_algo != Kex_Algo::STATIC_RSA) + throw Unexpected_Message("No server kex message, but negotiated a key exchange that required it"); + + if(!server_public_key) + throw Internal_Error("No server public key for RSA exchange"); + + if(auto rsa_pub = dynamic_cast<const RSA_PublicKey*>(server_public_key)) + { + const Protocol_Version offered_version = state.client_hello()->version(); + + rng.random_vec(m_pre_master, 48); + m_pre_master[0] = offered_version.major_version(); + m_pre_master[1] = offered_version.minor_version(); + + PK_Encryptor_EME encryptor(*rsa_pub, rng, "PKCS1v15"); + + const std::vector<uint8_t> encrypted_key = encryptor.encrypt(m_pre_master, rng); + + append_tls_length_value(m_key_material, encrypted_key, 2); + } + else + throw TLS_Exception(Alert::HANDSHAKE_FAILURE, + "Expected a RSA key in server cert but got " + + server_public_key->algo_name()); + } + + state.hash().update(io.send(*this)); + } + +/* +* Read a Client Key Exchange message +*/ +Client_Key_Exchange::Client_Key_Exchange(const std::vector<uint8_t>& contents, + const Handshake_State& state, + const Private_Key* server_rsa_kex_key, + Credentials_Manager& creds, + const Policy& policy, + RandomNumberGenerator& rng) + { + const Kex_Algo kex_algo = state.ciphersuite().kex_method(); + + if(kex_algo == Kex_Algo::STATIC_RSA) + { + BOTAN_ASSERT(state.server_certs() && !state.server_certs()->cert_chain().empty(), + "RSA key exchange negotiated so server sent a certificate"); + + if(!server_rsa_kex_key) + throw Internal_Error("Expected RSA kex but no server kex key set"); + + if(!dynamic_cast<const RSA_PrivateKey*>(server_rsa_kex_key)) + throw Internal_Error("Expected RSA key but got " + server_rsa_kex_key->algo_name()); + + TLS_Data_Reader reader("ClientKeyExchange", contents); + const std::vector<uint8_t> encrypted_pre_master = reader.get_range<uint8_t>(2, 0, 65535); + reader.assert_done(); + + PK_Decryptor_EME decryptor(*server_rsa_kex_key, rng, "PKCS1v15"); + + const uint8_t client_major = state.client_hello()->version().major_version(); + const uint8_t client_minor = state.client_hello()->version().minor_version(); + + /* + * PK_Decryptor::decrypt_or_random will return a random value if + * either the length does not match the expected value or if the + * version number embedded in the PMS does not match the one sent + * in the client hello. + */ + const size_t expected_plaintext_size = 48; + const size_t expected_content_size = 2; + const uint8_t expected_content_bytes[expected_content_size] = { client_major, client_minor }; + const uint8_t expected_content_pos[expected_content_size] = { 0, 1 }; + + m_pre_master = + decryptor.decrypt_or_random(encrypted_pre_master.data(), + encrypted_pre_master.size(), + expected_plaintext_size, + rng, + expected_content_bytes, + expected_content_pos, + expected_content_size); + } + else + { + TLS_Data_Reader reader("ClientKeyExchange", contents); + + SymmetricKey psk; + + if(key_exchange_is_psk(kex_algo)) + { + const std::string psk_identity = reader.get_string(2, 0, 65535); + + psk = creds.psk("tls-server", + state.client_hello()->sni_hostname(), + psk_identity); + + if(psk.length() == 0) + { + if(policy.hide_unknown_users()) + psk = SymmetricKey(rng, 16); + else + throw TLS_Exception(Alert::UNKNOWN_PSK_IDENTITY, + "No PSK for identifier " + psk_identity); + } + } + + if(kex_algo == Kex_Algo::PSK) + { + std::vector<uint8_t> zeros(psk.length()); + append_tls_length_value(m_pre_master, zeros, 2); + append_tls_length_value(m_pre_master, psk.bits_of(), 2); + } +#if defined(BOTAN_HAS_SRP6) + else if(kex_algo == Kex_Algo::SRP_SHA) + { + SRP6_Server_Session& srp = state.server_kex()->server_srp_params(); + + m_pre_master = srp.step2(BigInt::decode(reader.get_range<uint8_t>(2, 0, 65535))).bits_of(); + } +#endif +#if defined(BOTAN_HAS_CECPQ1) + else if(kex_algo == Kex_Algo::CECPQ1) + { + const CECPQ1_key& cecpq1_offer = state.server_kex()->cecpq1_key(); + + const std::vector<uint8_t> cecpq1_accept = reader.get_range<uint8_t>(2, 0, 65535); + if(cecpq1_accept.size() != CECPQ1_ACCEPT_BYTES) + throw Decoding_Error("Invalid size for CECPQ1 accept message"); + + m_pre_master.resize(CECPQ1_SHARED_KEY_BYTES); + CECPQ1_finish(m_pre_master.data(), cecpq1_offer, cecpq1_accept.data()); + } +#endif + else if(kex_algo == Kex_Algo::DH || + kex_algo == Kex_Algo::DHE_PSK || + kex_algo == Kex_Algo::ECDH || + kex_algo == Kex_Algo::ECDHE_PSK) + { + const Private_Key& private_key = state.server_kex()->server_kex_key(); + + const PK_Key_Agreement_Key* ka_key = + dynamic_cast<const PK_Key_Agreement_Key*>(&private_key); + + if(!ka_key) + throw Internal_Error("Expected key agreement key type but got " + + private_key.algo_name()); + + std::vector<uint8_t> client_pubkey; + + if(ka_key->algo_name() == "DH") + { + client_pubkey = reader.get_range<uint8_t>(2, 0, 65535); + } + else + { + client_pubkey = reader.get_range<uint8_t>(1, 1, 255); + } + + try + { + PK_Key_Agreement ka(*ka_key, rng, "Raw"); + + secure_vector<uint8_t> shared_secret = ka.derive_key(0, client_pubkey).bits_of(); + + if(ka_key->algo_name() == "DH") + shared_secret = CT::strip_leading_zeros(shared_secret); + + if(kex_algo == Kex_Algo::DHE_PSK || + kex_algo == Kex_Algo::ECDHE_PSK) + { + append_tls_length_value(m_pre_master, shared_secret, 2); + append_tls_length_value(m_pre_master, psk.bits_of(), 2); + } + else + m_pre_master = shared_secret; + } + catch(Invalid_Argument& e) + { + throw TLS_Exception(Alert::ILLEGAL_PARAMETER, e.what()); + } + catch(std::exception&) + { + /* + * Something failed in the DH/ECDH computation. To avoid possible + * attacks which are based on triggering and detecting some edge + * failure condition, randomize the pre-master output and carry on, + * allowing the protocol to fail later in the finished checks. + */ + rng.random_vec(m_pre_master, ka_key->public_value().size()); + } + + reader.assert_done(); + } + else + throw Internal_Error("Client_Key_Exchange: Unknown key exchange negotiated"); + } + } + +} + +} |