Cryptography Decrypted Book

Foreword.


Preface.


Introduction.

I. SECRET KEY CRYPTOGRAPHY.

1. Locks and Keys.

Locks and Combinations.

Defining Cryptographic Terms.

Making and Solving Puzzles.

Review.

2. Substitution and Caesar's Cipher.

Cryptanalysis of Caesar's Cipher.

Empowering the Masses.

The Importance of Separating the Method and the Key.

Adding Keys.

A Weakness of Caesar's Ciphers: The Failure to Hide Linguistic Patterns.

More Complex Substitution: Vigenere's Cipher.

Review.

3. Transposition Ciphers: Moving Around.

Patterns and Cryptanalysis.

Adding Complexity.

Computer Transposition.

Combining Substitution and Transposition.

Review.

4. Diffuse and Confuse: How Cryptographers Win the End Game.

Diffusion.

The Polybius Cipher.

The Principle of Confusion.

Cryptographic Locks and Keys.

Review.

5. DES Isn't Strong Anymore.

The Historical Need for an Encryption Standard.

Cycling Through Computer Keys.

Double and Triple DES.

DES (and Other Block Cipher) Modes.

The Avalanche Effect.

Supplement: Binary Numbers and Computer Letters.

Review.

6. Evolution of Cryptography: Going Global.

Early Cryptography.

Commercial and Military Needs.

Entering the Computer Age.

Review.

7. Secret Key Assurances.

Confidentiality.

Authentication.

An Authentication Attack.

Not Really Random Numbers.

Integrity.

Using the MAC for Message Integrity Assurance.

Why Bother Using a Message Authentication Code?

File and MAC Compression.

Nonrepudiation: Secret Keys Can't Do It.

Review.

8. Problems with Secret Key Exchange.

The Problem and the Traditional Solution.

Using a Trusted Third Party.

Key Distribution Center and Key Recovery.

Problems with Using a Trusted Third Party.

Growth in the Number of Secret Keys.

Trust and Lifetime.

Review.

II. PUBLIC KEY CRYPTOGRAPHY.

9. Pioneering Public Key: Public Exchange of Secret Keys.

The Search for an Innovative Key Delivery Solution.

Developing an Innovative Secret Key Delivery Solution.

First Attempt: A Database of Key/Serial Number Pairs.

Second Attempt: An Encrypted Database of Key/Serial Number Pairs.

Merkle's Insight: Individually Encrypted Key/Serial Number Pairs.

Black Hat's Frustrating Problem.

The Key to Public Key Technology.

A New Solution: Diffie-Hellman-Merkle Key Agreement.

Alice and Bob Openly Agree on a Secret Key.

Problems with the Diffie-Hellman Method.

Separate Encryption and Decryption Keys.

Review.

10. Confidentiality Using Public Keys.

New Twists on Old Security Issues.

Confidentiality Assurances.

Distribution of Public Keys.

Two-Way Confidentiality.

Review.

11. Making Public Keys: Math Tricks.

Alice's Easy Problem.

Grade School Math Tricks.

More Grade School Math.

Division and Remainders: Modular Math.

Modular Inverses.

Using Modular Inverses to Make a Public Key.

Putting It All Together.

Giving BlackHat a Difficult, Time-Consuming Problem.

Trapdoor to the Easy Problem.

Knapsack Cryptography.

Modulo Calculations.

Exercise: Find Which Numbers Sum to 103.

Review.

12. Creating Digital Signatures Using the Private Key.

Written and Digital Signature Assurances.

Reviewing and Comparing Authentication.

Secret Key Authentication.

Private Key Authentication 117

Authentication and Integrity Using Private and Secret Keys.

Private Key Authentication Methods.

RSA.

DSA.

Signing Terminology.

Nonrepudiation.

Assurances in Both Directions.

Summary of Public Key Assurances.

Public Key Means Public / Private Key.

Assurance Initiated.

Compressing before Signing.

Review.

13. Hashes: Non-keyed Message Digests.

Detecting Unintentional Modifications.

Detecting Intentional Modifications.

Signing the Message Digest.

Detecting BlackHat's Forgery.

Replay Attacks.

Supplement: Unsuccessfully Imitating a Message Digest.

Review.

14. Message Digest Assurances.

Two Message Digest Flavors.

Non-keyed Message Digest Assurances.

One-wayness.

Collision Resistance.

Weak Collision Resistance.

Examples of One-way and Weak Collision Resistance.

Strong Collision Resistance.

Non-keyed Digest Implementations.

Keyed Message Digest Assurances.

A MAC Made with DES.

DES-MAC Security.

Message Digest Compression.

Digest Speed Comparisons.

Hashed MAC.

Review.

15. Comparing Secret Key, Public Key, and Message Digests.

Encryption Speed.

Key Length.

Ease of Key Distribution.

Cryptographic Assurances.

Symmetric (Secret) Key.

Asymmetric (Public) Key.

Review.

III. DISTRIBUTION OF PUBLIC KEYS.

16. Digital Certificates.

Verifying a Digital Certificate.

Attacking Digital Certificates.

Attacking the Creator of the Digital Certificate.

Malicious Certificate Creator.

Attacking the Digital Certificate User.

The Most Devastating Attack.

Understanding Digital Certificates: A Familiar Comparison.

Issuer and Subject.

Issuer Authentication.

Transfer of Trust from the Issuer to the Subject.

Issuer's Limited Liability.

Time Limits.

Revoking Trust.

More than One Certificate.

Fees for Use.

The Needs of Digital Certificate Users.

Getting Your First Public Key.

Certificates Included in Your Browser.

Review.

17. X.509 Public Key Infrastructure.

Why Use X.509 Certificate Management?

What Is a Certificate Authority?

Application, Certification, and Issuance.

Certificate Revocation.

Polling and Pushing: Two CRL Delivery Models.

Building X.509 Trust Networks.

Root Certificates.

More Risks and Precautions.

Distinguished Names.

Certification Practice Statement.

X.509 Certificate Data.

Challenge Response Protocol.

Review.

18. Pretty Good Privacy and the Web of Trust.

The History of PGP.

Comparing X.509 and PGP Certificates.

Building Trust Networks.

Bob Validates Alice's Key.

Casey Validates Alice's Key Sent by Bob.

Dawn Validates Alice's Key Sent by Casey via Bob.

Web of Trust.

PGP Certificate Repositories and Revocation.

Compatibility of X.509 and PGP

Review.

IV. REAL-WORLD SYSTEMS.

E-mail Cryptographic Parameters.

Negotiation of SSL and IPsec Cryptographic Parameters.

User Initiation of Cryptographic E-mail, SSL, and Ipsec.

19. Secure E-mail.

Generic Cryptographic E-mail Messages.

Invoking Cryptographic Services.

Confidentiality and Authentication.

Choosing Services.

Positioning Services.

Deterring E-mail Viruses.

Review.

20. Secure Socket Layer and Transport.

Layer Security.

History of SSL.

Overview of an SSL Session.

An SSL Session in Detail.

Hello and Negotiate Parameters.

Key Agreement (Exchange).

Authentication.

Confidentiality and Integrity.

TLS Variations.

Anonymous Diffie-Hellman.

Fixed and Ephemeral Diffie-Hellman.

Comparing TLS, SSL v3, and SSL v2.

A Big Problem with SSL v2.

A Possible Problem with TLS and SSL.

Generating Shared Secrets.

Bob Authenticates Himself to AliceDotComStocks.

Review.

21. IPsec Overview.

Enhanced Security.

Key Management.

Manual Distribution.

Automated Distribution.

IPsec Part 1: User Authentication and Key Exchange Using IKE.

SSL/TLS and IPsec Key Agreement.

Security Association.

Phases.

IKE Nomenclature.

Benefits of Two-Phase Key Exchange.

IPsec Part 2: Bulk Data Confidentiality and Integrity for Message or File Transport.

Protocol and Mode.

ESP Examples.

AH Examples.

Management Control.

Implementation Incompatibilities and Complications.

Review.

22. Cryptographic Gotchas.

Replay Attack.

Man-in-the-Middle Attack.

Finding Your Keys in Memory.

Does Confidentiality Imply Integrity?

Example 1.

Example 2: Cut-and-Paste Attack.

Public Key as a Cryptanalysis Tool.

Example 1: The Chosen Plaintext Attack.

Public Key Cryptographic Standards.

Example 2: The Bleichenbacher Attack.

BlackHat Uses Bob's RSA Private Key.

Review.

23. Protecting Your Keys.

Smart Cards.

Types of Smart Cards.

What's Inside a Smart Card.

Protections and Limitations.

Smart Card Attacks.

Review.

Epilogue.

Appendix A. Public Key Mathematics (and Some Words on Random Numbers).

Appendix B. (A Few) IPsec Details.

Bibliography.

Index. 0201616475T04062001