Издательство John Wiley, 1996, -1027 pp.There are two kinds of cryptography in this world: cryptography that will stop your kid sister from reading your files, and cryptography that will stop major governments from reading your files. This book is about the latter. If I take a letter, lock it in a safe, hide the safe somewhere in New York, then tell you to read the letter, that’s not security. That’s obscurity. On the other hand, if I take a letter and lock it in a safe, and then give you the safe along with the design specifications of the safe and a hundred identical safes with their combinations so that you and the world’s best safecrackers can study the locking mechanism—and you still can’t open the safe and read the letter—that’s security.
For many years, this sort of cryptography was the exclusive domain of the military. The United States’ National Security Agency (NSA), and its counterparts in the former Soviet Union, England, France, Israel, and elsewhere, have spent billions of dollars in the very serious game of securing their own communications while trying to break everyone else’s. Private individuals, with far less expertise and budget, have been powerless to protect their own privacy against these governments.
During the last 20 years, public academic research in cryptography has exploded. While classical cryptography has been long used by ordinary citizens, computer cryptography was the exclusive domain of the world’s militaries since World War II. Today, state–of–the–art computer cryptography is practiced outside the secured walls of the military agencies. The layperson can now employ security practices that can protect against the most powerful of adversaries—security that may protect against military agencies for years to come.
Do average people really need this kind of security? Yes. They may be planning a political campaign, discussing taxes, or having an illicit affair. They may be designing a new product, discussing a marketing strategy, or planning a hostile business takeover. Or they may be living in a country that does not respect the rights of privacy of its citizens. They may be doing something that they feel shouldn’t be illegal, but is. For whatever reason, the data and communications are personal, private, and no one else’s business. This book is being published in a tumultuous time. In 1994, the Clinton administration approved the Escrowed Encryption Standard (including the Clipper chip and Fortezza card) and signed the Digital Telephony bill into law. Both of these initiatives try to ensure the government’s ability to conduct electronic surveillance.
Some dangerously Orwellian assumptions are at work here: that the government has the right to listen to private communications, and that there is something wrong with a private citizen trying to keep a secret from the government. Law enforcement has always been able to conduct court–authorized surveillance if possible, but this is the first time that the people have been forced to take active measures to make themselves available for surveillance. These initiatives are not simply government proposals in some obscure area; they are preemptive and unilateral attempts to usurp powers that previously belonged to the people.
Clipper and Digital Telephony do not protect privacy; they force individuals to unconditionally trust that the government will respect their privacy. The same law enforcement authorities who illegally tapped Martin Luther King Jr.’s phones can easily tap a phone protected with Clipper. In the recent past, local police authorities have either been charged criminally or sued civilly in numerous jurisdictions—Maryland, Connecticut, Vermont, Georgia, Missouri, and Nevada—for conducting illegal wiretaps. It’s a poor idea to deploy a technology that could some day facilitate a police state.
The lesson here is that it is insufficient to protect ourselves with laws; we need
to protect ourselves with mathematics. Encryption is too important to be left
solely to governments.
This book gives you the tools you need to protect your own privacy; cryptography products may be declared illegal, but the information will never be.Foundations
Part I—Cryptographic Protocols
Protocol Building Blocks
Basic Protocols
Intermediate Protocols
Advanced Protocols
Esoteric Protocols
Part II—Cryptographic Techniques
Key Length
Key Management
Algorithm Types and Modes
Using Algorithms
Part III—Cryptographic Algorithms
Mathematical Background
Data Encryption Standard (DES)
Other Block Ciphers
Still Other Block Ciphers
Combining Block Ciphers
Pseudo-Random-Sequence Generators and Stream Ciphers
Other Stream Ciphers and Real Random-Sequence Generators
One-Way Hash Functions
Public-Key Algorithms
Public-Key Digital Signature Algorithms
Identification Schemes
Key-Exchange Algorithms
Special Algorithms for Protocols
Part IV—The Real World
Example Implementations
Politics
Part V—Source Code
