Upload File

public key infrastructure (pki) jen-chang liu, 2004 ref1: ch.10, “ cryptography and network...

  • Home
  • Documents
  • Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and
46
Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “Cryptography and Network Security”, Stalling, 2003. Ref2: Ch.5, “Cryptography and Network Security”, A. Kahate, McGraw Hill, 2003. Ref3: Ch. 6, “RSA Security’s Official Guide to Cr yptography”, 2001

Upload: hunter-luscomb

Post on 14-Dec-2015

219 views

Category:

Documents


2 download

Report

Tags:

TRANSCRIPT

Page 1: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Public Key Infrastructure (PKI)

Jen-Chang Liu, 2004

Ref1: Ch.10, “Cryptography and Network Security”, Stalling, 2003.Ref2: Ch.5, “Cryptography and Network Security”, A. Kahate, McGraw Hill, 2003.Ref3: Ch. 6, “RSA Security’s Official Guide to Cryptography”, 2001

Page 2: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Outline

Key management in public-key cryptosystem

Public Key Certificate (PKC) X.509 standard

Public Key Infrastructure (PKI)

Page 3: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Key management (Ref1)

Two issues for public-key cryptosystem Distribution of public keys The use of public-key encryption to

distribute secret keys (keys for symmetric cipher)

Distribution of public keys Public announcement Public available directory Public-key authority Public-key certificates

Page 4: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

1. Public announcement

Drawback: the opponent can pretend to be another user

Ex. post public keys to public forums, such as USENET newsgroup and Internet mailing list

Page 5: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and
Page 6: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

2. Public available directory

Some trusted entity maintains a publicly available dynamic directory of public keys

Register the public key

Register the public key

{A, KUa }{B, KUb }

…

Attack: an opponent invades the public-key directory, and counterfeit public keys

Page 7: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

3. Public-key authority (Fig 10.3)

Central authority: 1. Maintain directory of public keys2. Each participant knows the public key for the

authority

A can confirmthe message fromthe authority

N1 :認證 B的身份N2 :認證 A的身份

Page 8: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Outline

Key management in public-key cryptosystem

Q: How to authenticate the association between the public key with the owner ?

Public Key Certificate (PKC) X.509 standard

Public Key Infrastructure (PKI)

Page 9: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Public key certificate (PKC 公開金鑰憑證 )

A public key certificate signifies the association between my public key and me Ex. Like a driver license

or passport

Q: Who can approve the association ?

A: A trusted entity – Certificate Authority (CA)

Q: What is the content of a digital certificate?

A: X.509 standard

Page 10: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Example: Digital certificate

Page 11: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

X.509 certificate format 1988, ITU X.509 version

1

Page 12: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

X.509 V2 extensions: unique identifier

V2 extensions: Issuer unique identifier Subject unique identifier

Motivation: Deal with the possibility that the issuer (CA’s name) name and the subject name (certificate holder’s name) might be duplicated over time

RFC2459 specifies that these two names should never be reused, so V2 extensions are made optional

Page 13: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

X. 509 V3 certificate extensions

Certificate Revocation List (CRL 憑證廢止列 )

Certificate policies

Authority key identifier: CA may havemultiple private-public key pairs. Thisfield defines which of these key pairsis used to sign the certificate

Key usage: 1. digital signature2. Certificate signing3. CRL signing4. Key enciphering5. Data enciphering6. Diffie-Hellman key exchange

Page 14: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Certificate Authority (CA 憑證簽發機構 )

CA is a trusted agency that can issue digital certificate. Ex. VeriSign, Entrust, …

Page 15: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Outline

Key management in public-key cryptosystem

Public Key Certificate (PKC) X.509 standard

Public Key Infrastructure (PKI) PKI components Certification creation steps Certificate hierarchies Certificate revocation

* Distribution of public keys is non-trivial

Page 16: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

PKI components The interaction

between PKI components End user Registration

authority (RA) CA Key recovery

server X.500 directory

Page 17: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Registration authority (RA)

RA: an intermediate entity between the end users and the CA Share the workload of CA

Accept and verify registration info about new users Generate keys on behalf of the end users Accept and authorize requests for key backups

and recovery Accept and authorize requests for certificate

revocation RA does not generate certificate

CA becomes an isolated entity, which makes it less susceptible to security attacks

Page 18: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Key recovery server

Q: End users lose their private keys? A: CA must revoke the corresponding PKC,

a new key pair must be generated, a new corresponding PKC must be

created A2: provide a key recovery server

CA backs up private keys at the time of creation

Page 19: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Certificate directory

Q: where to store the certificates? A1: end user stores on his local machine A2: CAs use a certificate directory (or a centr

al storage location) Provide a single point for certificate administrati

on and distribution (ex. for later certificate revocation)

Certificate directories need not to be trusted

Page 20: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Outline

Key management in public-key cryptosystem

Public Key Certificate (PKC) X.509 standard

Public Key Infrastructure (PKI) PKI components Certification creation steps (Ref2) Certificate hierarchies Certificate revocation

Page 21: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Certificate creation steps

Key generation

Registration

Verification

Certificate creation

Page 22: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

1. Subject generating his own key pair

2. RA generating a key pair for subject

1. RA knows private key!2. How to transmit it to user?

Page 23: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Registration ( 註冊、登錄 )

Certificate signing request (CSR)(PKCS#10, part of the Public KeyCryptography Standard)

Page 24: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

On-line registration example

Page 25: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Verification

1. RA verify the user’s credentials2. Check the Proof of Possession of the private

key Q: What if a user claims that she never

possessed the private key, when a document signed with her private key causes legal problems?

Sol 1: RA demands user to sign her CSR Sol 2: RA generates a random number, encrypt

it with the user’s public key, then challenge the user

…

Page 26: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Certificate creation

CA creates a digital certificate for the user Certificates in X.509 standard format Q: Why should we trust digital certificates?

Certificate goes to RA (or user) Certificate directory Backup user private key (if necessary)

Page 27: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Questions about certificate

Why should we trust digital certificate? Similar to: how do we verify a passport? How does the CA sign a digital certificate? How can we verify a digital certificate?

Page 28: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

X.509 certificate format

Page 29: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and
Page 30: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Question about CA’s public key

How do we get CA’s public key of some certificate ? Get CA’s certificate – which approve the assoc

iation between the public key with CA Who signs CA’s certificate?

The organization of CAs CA hierarchies and self-signed certificate Cross-certification

Page 31: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

CA hierarchy

Purpose: root CA can delegate job to lower CAs

Chain of trust

Page 32: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Self-signed certificate for root CA

Who signs for root CA?

1. Root CA is automatic consideredas trusted CA2. Software contains a pre-programmed,hard coded certificated of the root CA3. The root CA signs its own certificate (self-signed certificate)

Page 33: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Example: Self-signed root certificate

Page 34: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Cross-certificationRoot CAs in different countries

Page 35: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Outline

Key management in public-key cryptosystem

Public Key Certificate (PKC) X.509 standard

Public Key Infrastructure (PKI) PKI components Certification creation steps (Ref2) Certificate hierarchies Certificate revocation

Page 36: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Certificate revocation 憑證廢止 Ex. lost of credit card, driver license, … Reasons for certification revocation:

The private key is compromised The CA made mistakes while issuing a

certificate The certificate holder leaves a job,…

Before using a certificate, we check Does the certificate belong to the owner?

(check certificate signature) Is the certificate valid, or is it revoked?

Page 37: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

How to revoke a certificate?

Certificate has been issued, how to revoke it?

Page 38: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Certificate revocation list (CRL)

CRL is a list of revoked certificates published regularly by CA

Page 39: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Validating a certificate using CRL

Page 40: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Problems with CRL

1. CRL can be a large file -> long transmission time

Sol: delta CRL

2. CRL are published Periodically => cannot check online status

Sol: online certificate status check

Page 41: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Online Certificate Status Protocol

(HTTP)

CA setup this server

Page 42: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Key management (Ref1)

Two issues for public-key cryptosystem Distribution of public keys The use of public-key encryption to

distribute secret keys (keys for symmetric cipher)

Distribution of public keys Public announcement Public available directory Public-key authority Public-key certificates

Page 43: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

4. Public-key certificates 憑證 (Fig 10.4)

Certificate: contain public key and other information, generate from the certificate authority

Application mustbe in person or bysecure channel

1. Anyone can read, verify2. Only CA can create

Time: verify currency of certificate

Page 44: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Simple secret key distribution

Public-key scheme has slow data rate use public key to distribute secret key use secret key scheme for data encryption

session key(secret key)

E

KUe || IDA

intercept

KUe[ Ks ]E

KUa[ Ks ] Ks

Page 45: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

Secret key distribution with confidentiality and authentication

Against active and passive attacks

Authenticate B

Authenticate A

Confidentiality(only B can read)

authentication(only A can create it)

Page 46: Public Key Infrastructure (PKI) Jen-Chang Liu, 2004 Ref1: Ch.10, “ Cryptography and Network Security ”, Stalling, 2003. Ref2: Ch.5, “ Cryptography and

A hybrid and hierarchical scheme

KDC

A B C

Use public-key schemeto distribute master key

MKA

MKA

MKB

MKB

Use master keys with KDC to distribute session key

Ks Ks

Advantage: 1. Use master key to distribute session keys, instead of using

public-key scheme => faster !2. Backward compatible to old KDC scheme (master +

session key)


(1986) (Advanced Dungeons & Dragons) REF2: Player Character Record Sheets

William Stallings, Cryptography and Network Security 5/eWilliam Stallings, Cryptography and Network Security 5/e Author Dr Lawrie Brown Subject Lecture Overheads - Ch 6 Created Date

np3 Uji k Sampel-dep-Ref2.ppt

1 Codes, Ciphers, and Cryptography-Ch 2.2 Michael A. Karls Ball State University

04 Vessel Stirrers M e Ref2

Innovative field of cryptography: DNA cryptography

Basic Cryptography - Sapienzaparisi/Risorse/CryptographicPrimitives.pdf · Basic Cryptography Introduction ... The Java Cryptography Architecure (JCA) The Java Cryptography Extensions

Information Security Cryptography ( L02- Types Cryptography)

Scott CH Huang COM5336 Cryptography Lecture 11 Euclidean Domains & Division Algorithm Scott CH Huang COM 5336 Cryptography Lecture 10

1 Codes, Ciphers, and Cryptography-Ch 2.1 Michael A. Karls Ball State University

Ch 12 Cryptographic Hash Function - Faculty of … · 2016-11-10 · SCSR3443 Cryptography 26-Nov-15 m @ 2015/2016-1 1 Chapter 12 Cryptographic Hash Functions Forouzan, B.A. Cryptography

Java*Cryptography - Cogent Logic · Java*Cryptography Symmetric*Key*Cryptography • Cryptography. Cryptography

Cryptography Cryptography 1. Activity What is cryptography ? 2

Ch 12: Cryptography

Codes, Ciphers, and Cryptography-Ch 2.2

TSR - 9028 - REF2 - Player Character Sheet

1 Codes, Ciphers, and Cryptography-Ch 3.1 Michael A. Karls Ball State University

Scott CH Huang COM 5336 Cryptography Lecture 6 Public Key Cryptography & RSA Scott CH Huang COM 5336 Cryptography Lecture 6

Chapter 8 - Cryptography. Cryptography General Concepts

Cryptography - Report Advanced Cryptography Standard AES.pdf

BILLERID Biller Name Location Category Ref 1 Ref2 …...BILLERID Biller Name Location Category Ref 1 Ref2 Ref3 AECGAH Torrent Power Ltd Ahmedabad Electricity Consumer No NA Numeric

Man&Manetti Store Ref2

Cryptography - A Reviewweb.cse.msstate.edu/~ramkumar/review1.pdfSymmetric Cryptography Asymmetric Cryptography Key Management Network Security Symmetric Cryptography Overview Block

Tutoriel OverBlog MOOC REF2

Elementary Cryptography Chapter Outlinejfiore/2013/fall/5107/handouts/pfleeger/ch... · , Security in Computing, ch. 2 1 Security in Computing Chapter 2 Elementary Cryptography, Security

Scott CH Huang COM 5336 Cryptography Lecture 1 Scott CH Huang COM 5336 Cryptography Lecture 1 Introduction

Advanced Cryptography Isogeny-based Cryptography

Codes, Ciphers, and Cryptography Quantum Cryptography

Cryptography - Coding and Cryptography

Scott CH Huang COM 5336 Cryptography Lecture 7a COM 5336 Cryptography Lecture 7a Primality Testing Scott CH Huang 1

1 Codes, Ciphers, and Cryptography-Ch 2.3 Michael A. Karls Ball State University

Ch 11 Message Integrity and Authentication...SCSR3443 Cryptography 26-Nov-15 m @ 2015/2016-1 1 Chapter 11 Message Integrity and Message Authentication Forouzan, B.A. Cryptography and

From History of cryptography - frcatel.fri.uniza.sk · From History of cryptography Stanislav Palu´ch University of Zlina/Department of Mathematical Methodsˇ 9. okto´bra 2017 Stanislav

1 Codes, Ciphers, and Cryptography-Ch 3.2 Michael A. Karls Ball State University

(Continue) Cryptography - University of Washington · 2013-02-05 · Cryptography: Now on to asymmetric cryptography HW2 out soon (on cryptography) (Reminder:) Symmetric Cryptography