PGP: Pretty Good Privacy

Foreword. Preface. Part I: PGP Overview. Chapter 1: Introduction to PGP Why PGP? The Case for Encryption Your Mail Can Go Astray Protecting Your Privacy Where Did PGP Come from? Basic PGP Terminology Keys: Public, Secret, and Session Key Certificates Key Rings Pass Phrases Digital Signatures Signatures on Key Certificates How to Run PGP The Command Line Interface Getting Help (-h Option) Specifying Command Line Arguments Using ASCII Armor (-a Option) Encrypting and Signing Email (-e and -s Options) PGP File Extensions PGP Environment Variables PGP Configuration Variables The PGP Language File PGP and Its Competitors Key Certification with PGP. Chapter 2: Cryptography Basics How Does Simple Cryptography Work? Codes Ciphers Substitution ciphers One-Time Pads Keys and Key Length Breaking the Code Brute force (key search) attack Cryptanalysis Private Key Cryptography Private Key Algorithms A Private Key Example Problems with Private Key Cryptography The Key Distribution Center The Outlook for Private Key Public Key Cryptography Public Key Systems Advantages of Public Key Systems Digital Signatures Using Private and Public Key Cryptography Together How Good is Cryptography? The Strong and the Weak The Case for Weakness What Encryption Can't Do U.S. Restrictions on Cryptography Cryptography and the U.S. Patent System Cryptography and Export Controls Part II: Cryptography History and Policy. Chapter 3: Cryptography Before PGP Cryptography Through the Ages National Security and the NSA Lucifer and the DES The National Bureau of Standards The Security of the DES DES Cracking Alternatives to the DES Public Key Cryptography Ralph Merkle's Puzzles Diffie-Hellman Multi-User Techniques Diffie-Hellman Exponential Key Exchange The Birth of RSA How does RSA work? Technical Memorandum no.82 The Rise and Fall of Knapsacks Taking Public Key to Market. Chapter 4: A Pretty Good History of PGP Phil Zimmermann: On the Road to PGP Metamorphic Systems Charlie Merritt Phil Zimmermann Meets Public Key Face to Face with Jim Bidzos The Rise of RSA Data Security Working with Big Jim A Pretty Good Program The Anti-Crime Bill S.266 The Birth of PGP-Version 1.0 PGP Grows Up Bass-O-Matic The Real Thing-PGP Version 2.0 The Cypherpunks PEM, RSAREF, and RIPEM ViaCrypt MIT Steps in Throwing PGP into the Wind The Federal Investigation of Zimmermann Whither PGP? RSA-129 Solved! Chapter 5: Privacy and Public Policy Wiretapping and the U.S. Government The FBI's Digital Telephony Plan The Untold Cost of Digital Telephony Return of Digital Telephony Where's the Beef? An Information Superhighway that's "Wired for Sound" The NSA's Clipper Chip Inside Clipper Who Gets the Keys? The Battle over Clipper and the EES Problems with Clipper. Chapter 6: Cryptography Patents and Export Patents and Policy Export: 40 Bits is not Enough! The Digital Signature Standard The Battle over the DSS The DSS and Patents The Fall of PKP? The Cylink Lawsuit The Schlafly Lawsuit Part III: Using PGP. Chapter 7: Protecting Your Files Encrypting and Decrypting Files Encrypting a File Making a Mistake Erasing the Original File (-w Option) Retrieving Your Encrypted File (Default Option) The Pass Phrase Should You Use a Different Pass Phrase for Every File? How to Pick a Pass Phrase Good Pass Phrases Why Use a Long Pass Phrase? Chapter 8: Creating PGP Keys Making Public Key Cryptography Work The Theory Behind the Keys Using PGP to Create Keys (-kgOption) Choosing the Length of Your Public Key Entering Your User ID Picking Your Pass Phrase Creating Randomness What If PGP Won't Generate Keys? PGP Key Rings: A Place for Your Keys. Chapter 9: Managing PGP Keys Secret and Public Key Rings Viewing Keys (-kvOption) Viewing Keys on Your Public Key Ring Viewing Keys on Your Secret Key Ring Viewing Keys on Other Key Rings Getting More Information about Keys (-kvc Option) Changing Your Key Certificate (-keOption) Changing Your Pass Phrase Changing Your User ID (-ke Option) Editing with Options Changing Your User ID (-ke and -kr Options) Giving Your Public Key to Someone Copying Your Public Key Ring Extracting Your Public Key (-kx Option) Extracting Printable Keys with ASCII Armor (-kxa Option) Using Filter Mode (-f Option) Extracting Multiple Keys into a Single ASCII-Armored File Adding Keys to Key Rings (-kaOption) Adding Someone's Key to Your Public Key Ring Adding a Key to a Specified Key Ring No Duplicates Allowed Removing Keys from Key Rings (-krOption) Removing Keys from Your Public Key Ring Removing Keys from a Specified Key Ring A Starter Set of Public Keys. Chapter 10: Encrypting Email Sending Encrypted Email Step 1: Creating the Message Creating a message with your word processor Creating a message from the keyboard Running PGP in filter mode Step 2: Getting the Recipient's Public Key Step 3: Encrypting the Message (-e Option) Step 4: Sending the Message Doing It All at Once (-f Option) Encrypting and Sending a Message at the Same Time Typing, Encrypting, and Sending at the Same Time Receiving Encrypted Email Decrypting Email Changing the Output File (-o Option) Viewing the Decrypted File (-m Option) User Unknown Sending and Receiving Huge Documents Changing the Size of Armored Files Sending an Encrypted File to a Mailing List Encrypting and Sending to Multiple People Adding Yourself to the Mailing List Adding Yourself Automatically to the List. Chapter 11: Using Digital Signatures How Do Digital Signatures Work? The MD5 Message Digest Function Message Digests and Public Key RSA Digital Signatures PGP's Digital Signatures Signing a Message (-s Option) Verifying a Digital Signature Selecting from Multiple Secret Keys (-u Option) Signing and Encrypting a Message (-se Option) Receiving Signed Mail Creating Detached Signatures (-sb Option). Chapter 12: Certifying and Distributing Keys Forged Keys The Web of Trust Adding a Key with Signatures (-kaOption) Adding a Key for Phil's Pretty Good Pizza The fingerprint The certification Adding a Key for Terrence Talbot, Esq. Levels of trust Adding a Key for Sam Spade Viewing Signatures Checking Your Keys and Signatures (-kc Option) Checking Your Keys and Signatures (-kvv Option) Checking all the Fingerprints for Your Keys (-kvc Option) Changing Your Trust in a Person (-ke Option) Why Change the Level of Trust? Specifying a Different Key Ring Signing a Key (-ksOption) Signing with a Different Secret Key (-uOption) Removing a Signature (-krsOption) Unknown Signers Certifying the Keys in keys.asc (Version 2.6.1). Chapter 13: Revoking, Disabling, and Escrowing Keys Revoking Your Public Key What is a Key Revocation Certificate? Making a Key Revocation Certificate (-kd Option) Questions about Revoking Keys Disabling a Public Key (-kd Option) A Manual System for Escrowing Keys Simple Key Escrow Split-Key Escrow. Chapter 14: PGP Configuration File What is the PGP Configuration File? Where is the Configuration File? Editing the Configuration File Specifying a Configuration on the Command Line Inside the PGP Configuration File Configuration Variable Summary. Chapter 15: PGP Internet Key Servers Communicating with a Key Server Key Server Commands Getting Help Finding out Who is on the Server Adding Your Key to the Server Getting a Public Key from the Server Getting a Set of Public Keys Getting Updated Keys Where are the Key Servers? Part IV: Appendices A: Getting PGP Getting PGP from MIT What to Type Other Ways of Getting PGP University of Hamburg: Lots of Crypto Resources University of California at Berkeley: The Cypherpunks Netcom: The PGP FAQ and Other Information Electronic Frontier Foundation Other Sources B: Installing PGP on a PC Choosing a Directory Unpacking PGP Verifying Your Copy of PGP Setting up the Environment on a PC PGPPATH Environment Variable TZ Environment Variable A Sample autoexec.bat File Creating Your Secret Key/Public Key Pair C: Installing PGP on a UNIX System Unpacking PGP on UNIX Getting a C Compiler Building the RSAREF Library Building PGP Verifying Your Copy of PGP Finishing the PGP Installation Under UNIX The Dangers of Using PGP in a Multi-User Environment D: Installing PGP on a Macintosh Getting MacPGP Installing MacPGP Copying the File Decoding the File Creating a Setup Folder Creating a PGP Folder Launching MacPGP Creating Your Keys Adding Keys to Your Key Ring MacBinarizing the Distribution Certifying the Keys E: Versions of PGP F: The Mathematics of Cryptography How Diffie-Hellman Works How RSA Works The Security of RSA How Large is Very Large? How Random is Random? Dr. Ron Rivest on the Difficulty of Factoring Abstract Factoring Algorithms Costs of Computation Results Conclusions How PGP Picks Primes. Glossary. Bibliography Books Papers and Other Publications Electronic Resources. Index List of Figures 1-1: Threats to your message 1-2: Paper mail, with envelopes, provides privacy 1-3: Email, like postcards, offers little privacy 1-4: Information on a PGP public key certificate 1-5: PGP key rings 1-6: A digital signature 2-1: A simple example of encryption 2-2: Freemason cipher 2-3: George Washington's codebook 2-4: One-time pad 2-5: Brute force attack 2-6: Private key cryptography with three people 2-7: Private key cryptography with five people 2-8: Private key cryptography with a key distribution center ) 2-9: A session key from the KDC allows secure communication 2-10: Public key cryptography 7-1: Encrypting and decrypting a file 10-1: Encrypting email 10-2: Decrypting email 11-1: Signing a message 11-2: Verifying a message 11-3: Signing and encrypting a message 11-4: Decrypting and verifying a signature 12-1: The web of trust D-1: MacPGP self-extracting archive D-2: MacPGP distribution folder D-3: Files in the MacPGP folder D-4: PGP window used for messages D-5: Key menu (Generate key... option) D-6: Picking a key size D-7: Typing a pass phrase D-8: Key menu (Add keys... option) D-9: Adding keys from the keys.asc file D-10: Adding keys to the pubring.pgp file D-11: File menu (MacBinarize... option) D-12: MacBinarizing the MacPGP2.6-Installer file D-13: File menu (Open/Decrypt... option) D-14: Selecting a file for certification D-15: Specifying the filename for certification D-16: Specifyng the filename again for certification E-1:Versions of PGP List of Tables 3-1: Time required to break a DES-encrypted message 6-1: The public key cryptography patents F-1: Number of MIPS-years that can be bought for $1000 for low, average, and high levels of technological growth F-2: Number of MIPS-years that can be purchased by an attacker, combining money available and technological growth estimates F-3: Number of MIP-years required to factor a number in low, average and high scenarios F-4: Size of a number (in bits) that an attacker would be able to factor at various points of time under various scenarios 001 1565926412