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KERBEROS: THE MIT’S COMPUTERNETWORK PROTOCOL AND ITS

DEVELOPMENT

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KERBEROS

Third Party Authenticat

Strong Cryptography

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Origin

GreekMythology

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Modern History

Massachusetts

's nstitute o!TechnologyPro"ect Athena

Ste#e Millerand Cli$ord

%eu&an

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evolution

Early Kereros (#)* #+*#,-

Kereros .

Kereros /

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BASC 0ESG%

 Authentication Server

Ticket Granting Server

File Server

Key Distribution Center

CLIENT

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BASC 0ESG%

 AS

TGS

FS

CLIENT

1ser%a&e2 gichyPass3ord2 )+,./4

56

Client Secret Key

One 3ay

7ash

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BASC 0ESG%

 AS

TGS

FS

CLIENT

User gichy wants

to use !e ser"er

#$!ear

te%t&

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BASC 0ESG%

 AS

TGS

FS

CLIENT

Checks i!client isin the

dataase

Generates theClient

SecretKey

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BASC 0ESG%

 AS

TGS

FS

CLIENT

+ Messages

eing sent

A8 Client 9

TGSSession Key

B8 Ticket

GrantingTicketClientdecodes A21sing its

secret key

ClientCA%:T

decode B

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BASC 0ESG%

 AS

TGS

FS

CLIENT

C8 TicketGranting

Ticket !ro&

B

08Authenticat

or

TGSdecrypts Cand gets

TicketGrantingTicket

TGSdecrypts 0

using

Client9TGSSession keyand getsClient 0

and

TGS checksthat Client 0

!ro& C&atches

Client 0 !ro&0 and

ti&esta&pdoes not

e;ceed ticket#alidity

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BASC 0ESG%

 AS

TGS

FS

CLIENT

E8 Client<to<=S ticket=8Client9Ser#er Session

Key

Clientdecodes =

usingClient9TGS

session key*otains

Client9Ser#er Session

Key

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BASC 0ESG%

 AS

TGS

FS

CLIENT

E8 Client<to<=S ticket

G8Authenticat

or

=S decryptsE

=S decryptsG

=S checksthat Client 0

!ro& E&atches

Client 0 !ro&G and

ti&esta&pdoes not

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BASC 0ESG%

 AS

TGS

FS

CLIENT

78 The

ti&esta&p!ound in G>

encrypted

3ith theClient9Ser#er Session

Key

Clientdecrypts 7

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BASC 0ESG%

 AS

TGS

FS

CLIENT

Client

issuesser#icere?uest to

the =S

=S ser#ices

the re?uest

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O%C@1SO

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an( )ou