TLS handshake过程中的Hello消息

最新推荐文章于 2024-09-24 17:45:34 发布

原创

最新推荐文章于 2024-09-24 17:45:34 发布 · 2.1k 阅读

0 ·

CC 4.0 BY-SA版权

客户端在ClientHello消息中向服务器发送所支持的加密套件列表，按优先级排序。服务器根据此列表选择一种，若无法接受则返回错误并关闭连接。忽略不识别、不支持或不愿使用的加密套件。DH和DHE套件用于服务器认证，可选客户端认证，DHE参数由服务器签名以防止中间人攻击。如果客户端未提供签名算法扩展，服务器证书需用默认或指定的hash/signature算法签名。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

The cipher suite list, passed from the client to the server in the ClientHello message, contains the combinations of cryptographic algorithms supported by the client in order of the client's preference (favorite choice first). Each cipher suite defines a key exchange algorithm, a bulk encryption algorithm (including secret key length), a MAC algorithm, and a PRF. The server will select a ciphersuite or, if no acceptable choices are presented, return a handshake failure alert and close the connection. If the list contains ciphersuites the server does not recognize, support, or wish to use, the server MUSTignore those cipher suites, and process the remaining ones as usual.

Q: ignore具体代表什么意思？

uint8 CipherSuite[2];

cipher_suites
This is a list of the cryptographic options supported by the client, with the client's first preference first. If the session_id field is not empty (implying a session resumption request), this vector MUST include at least the cipher_suite from that session. Values are defined in Appendix A.5.

The Cipher Suite

The following values define the cipher suite codes used in the ClientHello and ServerHello messages.

A cipher suite defines a cipher specification supported in TLS Version 1.2.

TLS_NULL_WITH_NULL_NULL is specified and is the initial state of a TLS connection during the first handshake on that channel, but MUST NOT be negotiated, as it provides no more protection than an unsecured connection.

CipherSuite TLS_NULL_WITH_NULL_NULL = { 0x00,0x00 };

The following CipherSuite definitions require that the server provide an RSA certificate that can be used for key exchange. The server may request anysignature-capable （这个能力用在哪里？如果是RSA做密钥协商，是client选择随机数，并用server的公钥加密作为pms） certificate in the certificate request message.

CipherSuite TLS_RSA_WITH_NULL_MD5 = { 0x00,0x01 };
&n