SSL with New Client Authentication

Takuya Yahagi, S1090215University of AizuPerformance Evaluation Lab.

Purpose

To evaluate performance of SSL with client authentication with waiting time and probability of finding malicious user point of view.

Spoofing

Uses other’s or non-existent mail address to send phishing mail, spam and some kind of virus mail.

Sender ID (1)

Problem If IP address is also forged, Sender ID can’t prevent spoofing.

Sender Receiver DNS

Domain(2)

IP address(3)

SSL•Client hello(1)

•Random value Used to create common key•Cryptography algorithms list

• Server hello(2)•Random value Used to create common key•Selected algorithm

•Server certificate(2)•Public key

•Server hello done(2)

•Client key exchange(3)•Premaster secret Used to create common key

•Change cipher spec(3),(4) Signal of encryption

•Finished(3),(4)

ProblemThere is no client authentication.

Client hello (1)Client certificate

Server hello

Server certificate(2)

Server hello done

Client key exchangeChange cipher specFinished (3)

Change cipher spec

Finished (4)

ServerClient

Feige-Fiat-Shammir Identification Protocol

• Prove identity via demonstration of knowledge of secret without revealing even a single bit of secret.

• Malicious person, Mallory has 50% chance of passing this trial without secret number by guessing that Bob will send c = 0 or 1.

Alice Bob

w

crlmsr

lmwm

llst

s

cA

AA

A

mod Calculate

mod CalculateSelect

number. large is where ,mod:Open value

:numberSecret

2

2

lwtlr

c

cA modmodCheck

1or 0Select

2

Waiting time of SSL and SSL with authentication

Waiting time of SSL

Waiting time of SSL with authentication

S1 S2 S3

C1 C2

S4 S5

C3 C4 C5

W2

W1 W3 W4

W5C: ClientW: Waiting time of SSLS: Service time of SSL

S1 S3

A1 A2 M1 A3 A4

W2

W1 W3 W4

W5

A: AliceM: MalloryW: Waiting time of SSL with authenticationS: Service time of SSL with authenticationS2 S4 S5

Waiting Time of SSL

. where

,)1(2

][22

SSLNE

)1(2

2][

:SSL of time waitingof n valueExpectatio0 then same, always is SSL of timeService 2

SSLYE

Expectation of number of SSL clients:

SSL of timeservice of Variance:

SSL of timeservice Average:1

client incoming of Rate:

Waiting Time of SSL with Authentication(1)

2

2

22

)1()1()12(1][

)1(1][

x

x

x

xxn

x

xTVar

x

xTE

nn

M

n

M

Expectation value and variance of Mallory’s number of trials:

0][][

A

ATVar

nTE

Expectation value and variance of Alice’s number of trials:

trialsofNumber : trialoneper Mallory finding ofy Probabilit:

nx

][][ ][][

MauthM

SSLMauthMNVarsSVar

sNEsSE

SSL of timeService: trialof timeService:

SSL

authss

Expectation value and variance of Mallory’s and Alice’s service time of SSL with authentication:

0][][][][

AauthA

SSLAauthANVarsSVar

sNEsSE

Waiting Time ofSSL with Authentication(2)

. where

,)1(2

][22

authNE

tionauthentica with SSL of timeservice of Variance:

tionauthentica with SSL of timeservice Average:1

client incoming of Rate:

Expectation of number of SSL with authentication clients:

][

][ authauth

NEYE

Expectation value of waiting time of SSL with authentication:

Waiting Time

10 20 30 40 50 60

0.2

0.4

0.6

0.8

1Waiting time

n 20

n 15

n 5

No auth

Probability of Miss

5 10 15 20n

0.02

0.04

0.06

0.08

p(n)

Probability of missing Mallory in n trials: n

np

2

1)(

Conclusion and Future Works

Using the feature of this authentication, client can prove identity more securely.This method is solution to IP address spoofing.

However, service time of authentication and probability of Mallory is not accurate value.