21 internautes sur 22 ont trouvé ce commentaire utile
Dr. Lee D. Carlson
- Publié sur Amazon.com
Bypassing computer security systems has sometimes been called an art rather than a science by those who typically do not interact with computing machines at a level that would allow them to appreciate the science behind security attacks. This book does not address the strategies of how to bypass security systems, but instead concentrates on how to use cryptographic methods to corrupt the machines once access has been acquired. Clearly the authors are very excited about the developments in cryptovirology, a relatively young field, that have taken place in the last five years. Their goal though is not to train hackers to break into systems, but rather to coach the reader on how to find vulnerabilities in these systems and then repair them. The subject of cryptovirology is fascinating, especially in the mathematics that is uses, and a thorough knowledge of its power will be required for meeting the challenges of twenty-first century network computing.
After a "motivational chapter" that it meant to shed insight on what it is like to be a hacker, this being done through a collection of short stories, the authors move on to giving a general overview of the field of cryptovirology in chapter 2. The reader gets his first dose of zero-knowledge interactive proofs (ZKIPs), which allow a prover to convince a verifier of a fact without revealing to it why the fact is true. The authors point out that viruses are vulnerable once found, since their rudimentary programming can be then studied and understood. This motivates the introduction of public key cryptography into the payload of the virus, and it is at this point that the field of cryptovirology is born.
Chapter 3 is more of a review of modular arithmetic, entropy generators, and pseudorandom number generators and can be skipped for those readers familiar with these. The authors emphasize the need for effective random number generators and in using multiple sources for entropy generation. They also introduce the very interesting concept of a `mix network', which allows two mutually distrusting parties to communicate securely and anonymously over a network. `Onion routing' is discussed as a method for implementing asynchronous mix networks. Mix networks can be used to hide the propagation history of a worm or virus.
In chapter 4, the authors discuss how to implement anonymous communication and how to launch a cryptotrojan attack that utilizes an anonymous communication channel. There are many applications of anonymous communication, one being E-money, and also, unfortunately, money laundering. The authors describe in fair detail how to conduct criminal operations with mix networks and anonymous money. This same technology though allows freedom of speech in geographical areas that are not sympathetic to it. Electronic voting, so controversial at the present time, is discussed as an activity that is very susceptible to the threat of stegotrojans or government violation of anonymity. Techniques for doing deniable password snatching using cryptovirology, and for countering it using zero-knowledge proofs, are also discussed.
Chapter 5 introduces techniques for preventing the reading of counters when a virus is propagating from one machine to another. Known as `cryptocounters', the authors discuss various techniques for constructing them, such as the ElGamal and Paillier public key cryptosystems.
Private information retrieval (PIR), which allows the secure and private theft of information, is discussed in chapter 6, wherein the authors present a few schemes for performing PIR. These schemes, unfortunately, allow the theft of information without revealing anything about the information sought and without revealing anything about what is taken. The authors also introduce a concept that they call `questionable encryptions', which are algorithms to produce valid encryptions or fake encryptions depending on the inputs. Related to question encryption, and also discussed in this chapter, are `deniable encryptions', which allow the sender to produce fake random choices that result in the true plaintext to be kept secret. Also discussed is the topic of `cryptographic computing', which allows computations with encrypted data without first having to decrypt it. The modular arithmetic used in this chapter is fascinating and well worth the read.
Chapter 7 is by far the most interesting of the entire book, and also the most disconcerting if its strategies are ever realized. The goal of the chapter is to find out to what extent a virus can be constructed whose removal will damage the host machine. This, in the author's opinion, would be a genuine `digital disease', and they discuss various scenarios for bringing it about, which are at present not realized, but could be in the near future. The approach discussed involves game theory, and the authors show how the payload of a virus can survive even after discovery of the virus. They give a very detailed algorithm on how to attack a brokerage firm, including the assumptions that must be satisfied by such an attack. The attack is mounted by deploying a distributed cryptovirus that tries to find three suitable host machines, and the attack consists of three phases, the first involving replication leading to the infection of the three machines, the second involving preparation for the attack, and third involving playing the two-player game. The host machines, to be acceptable for launching the attack, must either be "brokerage" machines, which have sensitive information available to the virus, or "reclusive" machines, which are machines that are not subjected to much scrutiny. The goal of the virus, according to the authors, is to give the malware purchasing power, and not direct monetary gain. The virus may then evolve over time to become a portfolio manager, and may even act as a surrogate for purchasing shares on behalf of the firm or client. Other possibilities for the virus are discussed, and the authors overview the security of the attack and its utility.
I did not read the rest of the chapters in the book, so I will omit their review.
12 internautes sur 12 ont trouvé ce commentaire utile
John A. Faulkner
- Publié sur Amazon.com
This book presents an initial, interesting idea - could a computer virus be written that attacks a computer by encrypting the user's data? This could be a tool for extortion or a unique Denial of Service attack. Now this is not a new idea (eg: the KOH virus) but there is a new twist - the data is encoded with an asymmetric cipher, thus rendering it unrecoverable except to the virus writer. The authors state that such a virus has indeed been trialled in a proof-of-concept form, on a Macintosh SE30 (a nice machine to develop on, from memory) in System 6, so there's no "whoops, where's it gone?" problem. There is some detailed high level discussion of techniques and pitfalls. The authors then go on to describe how contemporary cryptographic technology may be adapted to the theft of information such as secure data and passwords. This is all done at the level of mathematical relationships - there is no viral code.
Two new words are added to the language - cryptovirology (the study of computer viruses with a cryptographic payload, usually malicious) and kleptography (the application of cryptography to data theft).
Here are a few chapter or section headings to give a taste of the themes running through this work: Through Hackers's Eyes; Cryptovirology; Deniable Password Snatching; Using Viruses to Steal Information; Computationally Secure Information Stealing; The Nature of Trojan Horses; Subliminal Channels.
The book starts with an accessible piece of fiction, but quickly progresses to the opaque style common to much academic writing in this field. The reader is well advised to brush up on matrix algebra, Jacobians and Abelian and non-Abelian groups and to have a working knowledge of computer viruses (however obtained). There are appendices intended to provide brief tutorials on computer viruses and public key cryptography. But both these very different specialised fields require far more study than any précis can provide.
While the writing is often hard going there is an enjoyable first chapter describing three incidents in the life of a virus writer (a student at a US university) as he writes and releases a virus. It provides a vicarious experience of the motivation for such activity - the mental challenge, the adrenalin rush and the exercise of secret power.
The writing, as referred to above, is uneven and there seems to be some confusion as to who the audience is for this work. Some seems to have come from one of the authors' doctoral thesis - you have been warned! It's an academic work, so academic cryptographers would be the principal readers. But since it's offered for sale to the public, one wonders who else would read it? We can rule out some groups. If you refer to yourself as "133t", then you can count yourself out, as can those wannabees who capture virus code, do a partial rewrite, add their handle, then release their "new" version. There is no rip-off virus code here. Even whoever wrote Nimda or Code Red or NetSky will find this heavy going, competent thought they are in the mysteries of mobile code and system calls. Certainly anti-virus software coders will find this of little use. If I can let my imagination run free, perhaps also the legendary Hidden Masters of cyberspace, those hackers beyond "elite" in their esoteric knowledge, who work alone, do not meet other hackers except deep behind some firewall and who are never suspected, let alone arrested, perhaps they will be inspired to even greater feats of data theft. But then we'd never know, would we?
9 internautes sur 11 ont trouvé ce commentaire utile
- Publié sur Amazon.com
For some time now we have been taught that modern cryptography offers an elegant solution to a number of problems. Communicate securely? use a VPN; identify the author of a document? use a digital signature; securely encrypt e-mail? use PKI. But what if the very power behind these solutions can itself be [misinterpreted]? If such is the case, then encryption can be a curse, a digital signature an illusion and the heralded savior an unconquerable nemesis. This is the essence of what this book is about.
To be sure this is not easy reading. It is adult material, meaning that thinking is required. But it could not be otherwise, the material would not allow it. However the reader will be well rewarded for every morsel of math they endeavor to puzzle through. The realization of the potential dark side of modern cryptography is the first step in preparing to defend against it. This book provides that realization.
The reader may find the first few chapters to be an entertaining fictional account of some days in the life of a hacker. Indeed, the text reads beautifully as such. But here is a chilling thought - what if the events described were real?
4 internautes sur 4 ont trouvé ce commentaire utile
- Publié sur Amazon.com
This book shows what type of viruses and other malware we may expect next, and which absolutely overshadow existing threats. Can you imagine a virus that encrypts your hard drive, then blackmails you for you to be able to decrypt it? How would such a virus work, and what can you do to protect yourself? The authors are clearly knowledgeable, both in terms of cryptography and malware, and the book is interesting and accessible. One can only hope that more good guys than bad guys read this book ... or we are all in trouble.
10 internautes sur 13 ont trouvé ce commentaire utile
- Publié sur Amazon.com
The whole first chapter of this book is a piece of low-grade Gibsonesque cyber-punk. The only thing missing is a reference to an Ono-Sendai "Samurai VII" cyber-deck. (This chapter is especially amusing, since the author makes references to "loading TSR programs." MS-DOS ???) Why are the authors killing trees with that kind of garbage in a book on malware technology?
The rest of the book is fairly informative, although it seems to be padded with a lot of supporting information about things like good vs. bad random number generators. People who have enough background to understand the threats the authors are describing probably don't need a refresher course in algorithms. People who DON'T have enough background probably won't be helped by the cursory treatment of these subjects given in the book.
All that being said, this is probably worth reading if you can get it for half off retail.