SSL 服务器中未指定的字节你好消息

Question

在 SSL 3.0 期间，服务器响应并显示以下服务器hello 消息

16 03 00 00 51 02 00
00 4d 03 00 4f a1 c1
eb e3 fb 00 a9 c8 25
25 48 6f 89 27 ec bb
80 f3 8c 5d db f7 6c
94 56 d8 34 7a b5 9d
02 20 54 ab 20 ea 05
a6 38 6f ee 55 40 ae
af e2 5d ae 2a 4d c1
c6 f4 09 a7 08 b1 c5
49 39 87 82 d3 f7 00
39 00 00 05 ff 01 00
01 00

我对此响应的理解如下：

Content-type: 22 (Handshake protocol)
Version: 3.0
Length: a1 (81 bytes)
Content-type: 02 (ServerHello)
Length: 4d (77 bytes)
Version: 3.0
Random: 4f a1 c1 eb e3 fb 00 a9
        c8 25 25 48 6f 89 27 ec
        bb 80 f3 8c 5d db f7 6c
        94 56 d8 34 7a b5 9d 02
SessionID Length: 20 (32 bytes)
SessionID: 54 ab 20 ea 05 a6 38 6f
           ee 55 40 ae af e2 5d ae
           2a 4d c1 c6 f4 09 a7 08
           b1 c5 49 39 87 82 d3 f7
Cipher Suite: 00 39
Compression method: 00

但我不明白最后 7 个字节应该如何解释：00 05 ff 01 00 01 00

Answer 1

这将是 RFC 5746 中定义的renegotiation_info扩展：

o  If this is the initial handshake for a connection, then the
   "renegotiated_connection" field is of zero length in both the
   ClientHello and the ServerHello.  Thus, the entire encoding of the
   extension is ff 01 00 01 00.  The first two octets represent the
   extension type, the third and fourth octets the length of the
   extension itself, and the final octet the zero length byte for the
   "renegotiated_connection" field.