Appendix A. Protocol Data Structures and Constant Values (协议数据结构和常量值)

本附录汇总 TLS 1.2 protocol 中使用的数据结构和常量值.

A.1. Record Layer (记录层)

struct {
    uint8 major;
    uint8 minor;
} ProtocolVersion;

ProtocolVersion version = { 3, 3 };  /* TLS v1.2 */

enum {
    change_cipher_spec(20), alert(21), handshake(22),
    application_data(23), (255)
} ContentType;

struct {
    ContentType type;
    ProtocolVersion version;
    uint16 length;
    opaque fragment[TLSPlaintext.length];
} TLSPlaintext;

struct {
    ContentType type;
    ProtocolVersion version;
    uint16 length;
    opaque fragment[TLSCompressed.length];
} TLSCompressed;

struct {
    ContentType type;
    ProtocolVersion version;
    uint16 length;
    select (SecurityParameters.cipher_type) {
        case stream: GenericStreamCipher;
        case block:  GenericBlockCipher;
        case aead:   GenericAEADCipher;
    } fragment;
} TLSCiphertext;

A.2. Change Cipher Specs Message

struct {
    enum { change_cipher_spec(1), (255) } type;
} ChangeCipherSpec;

A.3. Alert Messages (告警消息)

enum { warning(1), fatal(2), (255) } AlertLevel;

enum {
    close_notify(0),
    unexpected_message(10),
    bad_record_mac(20),
    decryption_failed_RESERVED(21),
    record_overflow(22),
    decompression_failure(30),
    handshake_failure(40),
    no_certificate_RESERVED(41),
    bad_certificate(42),
    unsupported_certificate(43),
    certificate_revoked(44),
    certificate_expired(45),
    certificate_unknown(46),
    illegal_parameter(47),
    unknown_ca(48),
    access_denied(49),
    decode_error(50),
    decrypt_error(51),
    export_restriction_RESERVED(60),
    protocol_version(70),
    insufficient_security(71),
    internal_error(80),
    user_canceled(90),
    no_renegotiation(100),
    unsupported_extension(110),
    (255)
} AlertDescription;

struct {
    AlertLevel level;
    AlertDescription description;
} Alert;

A.4. Handshake Protocol (握手协议)

enum {
    hello_request(0), client_hello(1), server_hello(2),
    certificate(11), server_key_exchange (12),
    certificate_request(13), server_hello_done(14),
    certificate_verify(15), client_key_exchange(16),
    finished(20),
    (255)
} HandshakeType;

struct {
    HandshakeType msg_type;
    uint24 length;
    select (HandshakeType) {
        case hello_request:       HelloRequest;
        case client_hello:        ClientHello;
        case server_hello:        ServerHello;
        case certificate:         Certificate;
        case server_key_exchange: ServerKeyExchange;
        case certificate_request: CertificateRequest;
        case server_hello_done:   ServerHelloDone;
        case certificate_verify:  CertificateVerify;
        case client_key_exchange: ClientKeyExchange;
        case finished:            Finished;
    } body;
} Handshake;

A.5. The Cipher Suite (密码套件)

TLS 1.2 定义的 cipher suite identifier 包括 RSA, DH, DHE 和 anonymous DH 组合, 使用 NULL, RC4, 3DES, AES-CBC, SHA, SHA256 等算法. TLS_RSA_WITH_AES_128_CBC_SHA 是 mandatory-to-implement cipher suite.

A.6. The Security Parameters (安全参数)

SecurityParameters 描述当前 connection state 所需的 PRF algorithm, bulk cipher algorithm, cipher type, MAC algorithm, compression algorithm, master secret, client random 和 server random.