TLS 1.3 Handshake Protocol

Sun, 21 Oct 2018 10:05:36 +0000

握手协议用于协商连接的安全参数。握手消息被提供给 TLS 记录层，在记录层它们被封装到一个或多个 TLSPlaintext 或 TLSCiphertext 中，它们按照当前活动连接状态进行处理和传输。

 enum {
 client_hello(1),
 server_hello(2),
 new_session_ticket(4),
 end_of_early_data(5),
 encrypted_extensions(8),
 certificate(11),
 certificate_request(13),
 certificate_verify(15),
 finished(20),
 key_update(24),
 message_hash(254),
 (255)
 } HandshakeType;

 struct {
 HandshakeType msg_type; /* handshake type */
 uint24 length; /* remaining bytes in message */
 select (Handshake.msg_type) {
 case client_hello: ClientHello;
 case server_hello: ServerHello;
 case end_of_early_data: EndOfEarlyData;
 case encrypted_extensions: EncryptedExtensions;
 case certificate_request: CertificateRequest;
 case certificate: Certificate;
 case certificate_verify: CertificateVerify;
 case finished: Finished;
 case new_session_ticket: NewSessionTicket;
 case key_update: KeyUpdate;
 };
 } Handshake;

协议消息必须按照一定顺序发送(顺序见下文)。如果对端发现收到的握手消息顺序不对，必须使用 “unexpected_message” alert 消息来中止握手。

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TLS 1.3 Handshake Protocol