Securing e GovernmentSecuring e GovernmentPublic Key InfrastructurePublic Key Infrastructure

Prof Dr Mohamed KoutaProf Dr Mohamed KoutaChairman Of MIS DepartmentChairman Of MIS Department

Arab Academy For Science And TechnologyArab Academy For Science And Technology

OutlineOutline

Security Requirements.Security Requirements. Symmetric Key Cryptosystem.Symmetric Key Cryptosystem. Asymmetric (Public) Key Cryptosystem.Asymmetric (Public) Key Cryptosystem. Over View of Digital Signature.Over View of Digital Signature. Secure Socket Layer Protocol.Secure Socket Layer Protocol. Digital Certificate.Digital Certificate. Certificate Authority.Certificate Authority. PKI Components.PKI Components. PKI Implementation.PKI Implementation. Using biometrics and Smart Token.Using biometrics and Smart Token. PKI Assessment.PKI Assessment.

Security RequirementsSecurity Requirements

Privacy.Privacy. Authenticity.Authenticity. Non repudiationNon repudiation Integrity.Integrity.

Symmetric Key Cryptosystem

Poly alphabetic Cipher

Consider a key length = 4

Key = BAND1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

 

Plain Text M= E BUS INES S

B AND BAND B

Cipher Text E(M)= G CIW KOSW U

 

Symmetric-key Cryptosystems

Encryption

Es

Decryption DsSender Receiver

M M

C

Secret

Key

Secret

Key

Secure ChannelSecret

Key

Intruder

Overview

Symmetric-key Cryptosystems

Encryption

Es

Decryption DsSender Receiver

M M

C

Secret

Key

Secret

Key

Secure ChannelSecret

Key

Intruder

Overview

Asymmetric-key Cryptosystems

Encryption

EK

Decryption DKSender Receiver

M M

C

Public

Key

Private

Key

Intruder

Overview

Overview of Digital SignatureOverview of Digital Signature

Signer’s Private Key

SignedDocument

EncryptedDigestHash

Algorithm

Digest

Remember, a digital signature involves services provided by Certificate Authority (CA)

Verifying the Digital SignatureVerifying the Digital Signaturefor Authentication and Integrityfor Authentication and Integrity

Hash Algorithm

Digest

Digest??

Signer’sPublic Key

And so does the process of verifying the validity of a digital signature

Sender’s ComputerSender’s Private Signature Key

Sender’s Certificate

+

+

Message

+Digital Signature

Receiver’s Certificate

Encrypt

Symmetric Key

Encrypted Message

Receiver’sKey-Exchange Key

Encrypt

DigitalEnvelope

Message

Message Digest

10© Prentice Hall, 2000

Receiver’s Computer

DecryptSymmetric

Key

Encrypted Message

Sender’s Certificate

+

+

Message

compare

DigitalEnvelope

Receiver’s Private Key-Exchange Key

Decrypt

Message DigestDigital SignatureSender’s Public Signature Key

Decrypt

Message Digest

11© Prentice Hall, 2000

Digital CertificateDigital Certificate

X509 StandardX509 StandardEach certificate contains theEach certificate contains the

public-key of a user and is signedpublic-key of a user and is signed

with the private-key of a trusted with the private-key of a trusted

certificate authoritycertificate authority

CertificateCertificate AuthorityAuthority

In an uncontrolled system, anyone could publish a In an uncontrolled system, anyone could publish a new public-key and assume a new identity.new public-key and assume a new identity.

Any Participant can send his public-key to any other Any Participant can send his public-key to any other one broadcast the keyone broadcast the key

CertificateCertificate AuthorityAuthority

This would be like allowing anyone to issue his or This would be like allowing anyone to issue his or her own passport or driving licensesher own passport or driving licenses

This is clearly unacceptable for any application that, This is clearly unacceptable for any application that, like electronic commerce, requires authentication like electronic commerce, requires authentication and non-repudiation.and non-repudiation.

In order to assure a proper information exchange In order to assure a proper information exchange mechanism, an important entity should be involved mechanism, an important entity should be involved in the process which is the Certificate Authority in the process which is the Certificate Authority (CA).(CA).

CertificateCertificate AuthorityAuthority

Cont. Distribution of Public KeysCont. Distribution of Public Keys

Public key CertificatePublic key Certificate

CertificateCertificate AuthorityAuthority

Requirements of setting up the CARequirements of setting up the CA1.1. Compatibility with existing Internet based Certificate Compatibility with existing Internet based Certificate

AuthoritiesAuthorities It should be possible to use the certificates in It should be possible to use the certificates in

applications such as Netscape navigators, secure email, applications such as Netscape navigators, secure email, and custom built business-to-business e-commerce and custom built business-to-business e-commerce applications.applications.

Certificates must be consistent with accepted Certificates must be consistent with accepted standards; such the widely recognized X.509 standards; such the widely recognized X.509 certificate formats.certificate formats.

Certificate AuthorityCertificate Authority

Effective Distribution mechanismsEffective Distribution mechanisms Directory server support:-Directory server support:-

includes client certificates, and certificate validity includes client certificates, and certificate validity status.status.

Certificates accompanying signatures:-Certificates accompanying signatures:- The certificate, being signed by the ECA, enables the The certificate, being signed by the ECA, enables the

receiving party to check the validity of both the receiving party to check the validity of both the certificate, and the accompanying signature.certificate, and the accompanying signature.

Support for certificate revocation:-Support for certificate revocation:-

Certificate AuthorityCertificate Authority

Revocation of Revocation of CertificatesCertificates The user’s private key The user’s private key

is compromisedis compromised The user is no longer The user is no longer

certified by this CAcertified by this CA The CA’s certificate is The CA’s certificate is

compromisedcompromised

Certificate management Certificate management cyclecycle

User

CertificateAuthority

Program

Request a certificateSend browser form

Send public key

Request certificatefor key linked with LIR ID

Certificate

CA never sees the private key

Certificate

Certificate

Some time later the user wants to revoke the certificate…

Revocation requestCertificate is included

in the Certificate Revocation List (CRL)

PKI ComponentPKI Component

Certificate Authority (CA).Certificate Authority (CA). Issues Digital CertificatesIssues Digital Certificates

Authorization Authority (AA).Authorization Authority (AA). Response for Digital Certificate (DC) requestResponse for Digital Certificate (DC) request

Registration Authority (RA).Registration Authority (RA). Contains a database for DC and Certificate Revocation ListContains a database for DC and Certificate Revocation List CRL.CRL.

Directory Services.Directory Services. Handles DC exchange.Handles DC exchange.

Applications.Applications.

PKI ImplementationPKI Implementation

Issuing the Certificate Practice Statement Issuing the Certificate Practice Statement (CPS).(CPS).

A statement of Practices that CA employs in issuing DC.A statement of Practices that CA employs in issuing DC.

Building the PKI as according CPS.Building the PKI as according CPS. Training for users and administration Staff.Training for users and administration Staff. Connections to secured systems that could Connections to secured systems that could

circumvented the PKI must be ended.circumvented the PKI must be ended. Integration with the different applications. Integration with the different applications.

Using Biometrics and Using Biometrics and Smart Token inSmart Token in

Electronic signature Electronic signature

How a citizen can apply for a Smart TokenHow a citizen can apply for a Smart Token Step 1Step 1 The citizen (Applicant A) provides his National Security Number Card (NSN)The citizen (Applicant A) provides his National Security Number Card (NSN) to to

one of the Service Provider (SP).one of the Service Provider (SP). Step 2Step 2 SP sends the NSN information to the CA.SP sends the NSN information to the CA. Step 3Step 3 CA checks for Applicant already has a DC or revoked with RA.CA checks for Applicant already has a DC or revoked with RA. Step 4Step 4 If A is applying first time, CA asks for authorization from AA.If A is applying first time, CA asks for authorization from AA. Step 5Step 5 AA responses for CA.AA responses for CA. Step 6Step 6 CA asks A to generate his keys pair.CA asks A to generate his keys pair. Step 7Step 7 The Two pairs are generated inside the applicant smart Token.The Two pairs are generated inside the applicant smart Token. Step 8Step 8 The public Key is sent to the CA.The public Key is sent to the CA. Step 9Step 9 The CA generates and sends the DC back to the applicant Token.The CA generates and sends the DC back to the applicant Token. Step 10Step 10 The token is trained for the applicant finger print. The token is trained for the applicant finger print.

Sender side Pre Session StagePre Session Stage

CA

2 check validity

Sender (S) Receiver (R)

1 S w

ants

to c

omm

unicat

e w

ith R

3 SDC

3 R

DC

Sender side

ESM + DE

Sender PC

Sender Token

Sender Data

MD

SDS +SDC

1- Selecting the message M to be sent from the sender PC (SPC).

2- According to the Hashing Algorithm (HA) stored in the SPC , M will be hashed and the message digest (MD)

will be generated.

3- The message digest MD is transferred from the SPC to the sender Smart Token (SST).

6- Using a random number generator (RNG), a session key (SK) will be generated inside the SPC.

7- Encrypting M+SDS+SDC using symmetric key encryption algorithm SKEA and Sk as encryption key and call it the encrypted signed message (ESM).

8- Extracting the receiver public key (RPUK) from the RDC available in the SCL.

9- Encrypt the SK with RPUK using PKUK to create Digital Envelop (DE) send ESM+DE.

4- Using public key cryptographic algorithm (PKCA) ,the MD is encrypted with the sender private key (SPRK) to get the sender digital signature (SDS).

5- The SDS+ a copy from the sender digital certificate (SDC) are sent back to the SPC.

Sender side Third ProcessThird Process

Receiver PC

DE

Encrypted Signed message (ESM)Encrypted session keyBy receiver public key (DE)

Sender PC

ESM+

1-DE is sent to the receiver smart token (RST).

4- By the SK the message will be Decrypted using the same SKEA Now we have : M+ SDS + SDC.

5- The SDC received from CA is compared with SDC received from the sender to assure its validity. If its valid the procedure continue , aborted otherwise. 6- Decrypt the SDS by the sender public key SPUK contained in the SDC to get MD. Call it MD1.

8- Using M generate a message digest MD using the same HA. Call it MD2.

7- Compare the two digests MD1 and MD2. If MD1 and MD2 are identical then message accepted otherwise the message is rejected.

Receiver PC

Receiver side

2- Using PKEA the DE is Decrypted by the RPRK to get the session key SK.

3- Send SK back to the RE PC

Receiver Token

ESM + DE

Received Data

DE

SK

Token blank containToken blank contain

1- RSA Encryption/decryption Algorithm.1- RSA Encryption/decryption Algorithm.

2- USB Interface.2- USB Interface.

3- Biometric sensor.3- Biometric sensor.

4- Image processing.4- Image processing.

5- Feature extraction & recognition.5- Feature extraction & recognition.

6- ROM.6- ROM.

7- RAM7- RAM

Smart Token Block

Biometric Device

Interface Bus

USB including power supply

Token Block Diagram

SMART TOKEN BLOCKU

SB

inte

rfac

e

BUS

Biometric Interface

ROMPrivate KeyCertificate contain Public KeyFinger print of the owner

RAMProcessing and result storage RSA En /Dec

Algorithm& Key Generation

Biometric Device

Interface Bus

Power supply from USB

Control unitFeature extraction & recognition

Image

processing

USB

BUS

Biometric Verification for Biometric Verification for Smart TokenSmart Token

AT77C101B-CB02V AT77C101B-CB02V SensorSensor

Architecture of the Architecture of the automatic identity automatic identity

authentication systemauthentication system

Image processing and Image processing and extraction of fingerprint extraction of fingerprint

minutiaminutia

Step (1) Input ImageStep (1) Input Image

Step (2) Region of Step (2) Region of InterestInterest

Step (3) Orientation Step (3) Orientation FieldField

Step (4) Ridge DetectionStep (4) Ridge Detection

Ridge ending and ridge bifurcation.

Step (5) Extracted Step (5) Extracted RidgesRidges

Step (6) Thinned RidgesStep (6) Thinned Ridges

Step (7) Smoothing Step (7) Smoothing procedureprocedure

• • The presence of undesired spikes and breaks present in a The presence of undesired spikes and breaks present in a thinned ridge map may lead to many spurious thinned ridge map may lead to many spurious minutiae being detected.minutiae being detected.

• • Therefore, before the minutiae detection, a smoothing Therefore, before the minutiae detection, a smoothing procedure is applied to remove spikes and to join procedure is applied to remove spikes and to join broken ridges.broken ridges.

Step (8) Minutiae Step (8) Minutiae detectiondetection

Last Step Minutia Last Step Minutia ExtractionExtraction

MinutiaeMinutiae M Matchingatching

Alignment of the input ridge and the template ridge

Applying the matching Applying the matching algorithm to an input algorithm to an input

minutiae set and a minutiae set and a templatetemplate

(a) input minutiae set (b) template minutiae set

Applying the matching Applying the matching algorithm to an input algorithm to an input

minutiae set and a minutiae set and a templatetemplate (Cont.) (Cont.)

(c) alignment result based on the minutiae marked with green circles

(d) matching result where template minutiae and their correspondences are connected by green lines.

PKI AssessmentsPKI Assessments

CPSCPS CACA AAAA RARA CRL policies.CRL policies. Certificate Usage with applications.Certificate Usage with applications. Auditing.Auditing. Cryptographic devices and dataCryptographic devices and data Cryptographic AlgorithmsCryptographic Algorithms Critical Information Flow.Critical Information Flow. Sensitive Software Applications.Sensitive Software Applications. Key Managements.Key Managements. Network Devices Hosts, Routers, firewalls, switches).Network Devices Hosts, Routers, firewalls, switches).

Examples forExamples for PKI applications PKI applications

E-mail.E-mail. E-Gov services (Pension, ..).E-Gov services (Pension, ..). E-Election (voting).E-Election (voting). Group decision making.Group decision making. Multi signature.Multi signature. Notarizing.Notarizing. E-payment.E-payment. Medical care.Medical care.

Note:Note: It is up to the application to deploy the smart token. It is up to the application to deploy the smart token.