Data (in the example, the 4-byte ASCII string "ping").Data length (2 bytes, network byte order).Protocol version (2 bytes, as in header).Sequence number (unsigned 64-bit integer, network byte order uniquely identifies this record in this direction counts from zero for all encrypted traffic including the handshake-finished messages, each direction has independent sequence numbers).Message (the following fields concatenated without spacing):.The key is the same for all messages sent in a given direction within a particular session. Key: determined from the exchanged pre-master secret client and server use different keys to create the MAC (and the other's key to verify the MAC).The MAC is an HMAC (Hash-based Message Authentication Code) using the hash algorithm specified in the cipher suite (SHA1 in the example, SHA2-256 in your question) as the pseudo-random function, and computed from the following data: Padding using a modified version (every padding byte is reduced by one) of the padding defined in PKCS#7( ) (brings the plaintext length to a multiple of the block size which for AES is 16 bytes always at least one byte of padding to avoid ambiguity so will be 1-16 bytes inclusive 8 bytes in the example).The MAC (in the example, HMAC-SHA1, which is 20 bytes with your cipher suite, HMAC-SHA2-256, which is 32 bytes).The actual message payload (In the example, the ASCII string "ping", 4 bytes).The plaintext of the message is as follows: Encrypted payload (AES in CBC mode always produces a multiple of the block length which is 16 encrypted plaintext includes the MAC example is 32 bytes long).Encryption IV (16 bytes for AES, unique for every encryption).big-endian, does not include the header length but does include the IV) Record payload length (2 bytes, network byte order a.k.a.TLS version (2 bytes, major and minor version, 1-indexed, includes SSL versions, so TLS 1.2 is 0x03, 0x03).
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |