Network protocol, history, uses, application, procedures

2. Third Party Authenti
Strong Cryptograph

4. Modern History
Massachusetts's
Institute of
Technology
Project Athena
Steve Miller
and Clifford
Neuman

5. evolution
Early Kerberos (v1, v2, v3)
Kerberos 4
Kerberos 5

6. BASIC DESIGN
Authentication Server
Ticket Granting Server
File Server
Key Distribution Center
CLIENT

7. BASIC DESIGN
AS
TGS
FS
CLIENT
UserName: gichy
Password: 12345?><
Client Secret Key
One way Hash

8. BASIC DESIGN
AS
TGS
FS
CLIENT
User gichy wants to
use file server
(clear text)

9. BASIC DESIGN
AS
TGS
FS
CLIENT
Checks if
client is in
the database
Generates
the Client
Secret Key

10. BASIC DESIGN
AS
TGS
FS
CLIENT
2 Messages
being sent
A. Client / TGS
Session Key
B. Ticket
Granting Ticket
Client decodes A:
Using its secret
key
Client CAN’T
decode B

11. BASIC DESIGN
AS
TGS
FS
CLIENT
C. Ticket
Granting Ticket
from B
D.
Authenticator
TGS decrypts C
and gets Ticket
Granting Ticket
TGS decrypts D
using
Client/TGS
Session key and
gets Client ID
and Timestamp
TGS checks that
Client ID from C
matches Client ID
from D and
timestamp does
not exceed ticket
validity period

12. BASIC DESIGN
AS
TGS
FS
CLIENT
E. Client-to-FS
ticket
F. Client/Server
Session KeyClient decodes F
using Client/TGS
session key,
obtains
Client/Server
Session Key

13. BASIC DESIGN
AS
TGS
FS
CLIENT
E. Client-to-FS
ticket
G.
Authenticator
FS decrypts EFS decrypts GFS checks that
Client ID from E
matches Client ID
from G and
timestamp does
not exceed validity
period

14. BASIC DESIGN
AS
TGS
FS
CLIENT
H. The
timestamp
found in G + I
encrypted with
the
Client/Server
Session Key
Client decrypts
H

15. BASIC DESIGN
AS
TGS
FS
CLIENT
Client issues
service request
to the FS
FS services the
request

17. hank You