14-01-2013, 02:21 PM
TLS (Transport Layer Security)
TLS.docx (Size: 17.6 KB / Downloads: 26)
• IETF standard RFC 2246 similar to SSLv3
• with minor differences
– in record format version number
– uses HMAC for MAC
– a pseudo-random function expands secrets
– has additional alert codes
– some changes in supported ciphers
– changes in certificate negotiations
– changes in use of padding
1.Version number
• TLS Record Format is same as SSL Record Format
• Difference in version values
• Major version is 3
• Minor version is 1
2.Message Authentication Code
• Uses HMAC Algorithm
HMACK = Hash[(K+ XOR opad) |
Hash[(K+ XOR ipad)|M)]]
• MAC calculation
HMAC_hash(MAC_write_secret,seq_num|TLSCompressed.type | TLSCompressed.version | TLSCompressed.length | TLSCompressed.fragment))