Good Books

Welcome to Crypto. We hope you enjoy your visit.

You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are some features you can't use. If you join our community, you'll be able to access member-only sections, and use many member-only features such as customizing your profile, sending personal messages, and voting in polls. Registration is simple, fast, and completely free.

Join our community!

If you're already a member please log in to your account to access all of our features:

Pages:
1
2
3

Good Books; Add a favourite crypto book to the list
Topic Started: Oct 2 2005, 06:47 AM (1,321 Views)
insecure	Oct 2 2005, 06:47 AM Post #1
Elite member Posts: 381 Group: Trusted Member Member #10 Joined: September 9, 2005	"Applied Cryptography", 2nd edition, Bruce Schneier. Well worth the cash. Discusses some pretty heavy crypto. (Just pre-dates AES, so look out for a 3rd edition in case one happened whilst I wasn't looking.)



Revelation	Oct 2 2005, 07:15 AM Post #2
Administrator Posts: 386 Group: Admin Member #1 Joined: August 23, 2005	Thanks for the tip, this book might be in the local library
	RRRREJMEEEEEPVKLWENFNVJKEEEEEAOLKAFKLXCFZAASDJXZTTTTTTTLSIOWJXMOKLAFJNNKFNXN RAGRBAQEMHIGDJVDSEOXVIYCELFHWLELJFIENXLRATALSJFSLCYTKLASJDKMHGOVOKAJDNMNUITN RRRRLJVEEEEECLYVYHNVPFTAEEEEEMWLMEIRNGLARWJAKJDFLWNTIERJMIPQWOTZEOCXKNUBNXCN RJIRPOWEANFUSNCZVDVZNMSFEKLOEPZLDKDJWSAAAAAAAOERHJCTNCKFRIMVKSOFOMKMANREWNBN RZUDRGXEEEEENFQIDVLQNCKNEEEEEDGLLLLLLAWIOSNCDARLODMTOEJXMILDFJROTKJSDNLVCZNN


rot13	Oct 3 2005, 07:58 PM Post #3
Elite member Posts: 306 Group: Trusted Member Member #14 Joined: September 29, 2005	If you like classical cryptography, I enjoyed "Cryptanalysis" by Helen Fouche Gaines (originally titled Elementary Cryptanalysis). For modern cryptography, in addition to Schneier's book, you might look at Douglas Stinson's "Cryptography: Theory & Practice".



cows	Oct 10 2005, 04:55 PM Post #4
Unregistered	Not really a book for learning Crypto but an interesting book in the least: Digital Fortress by Dan Brown Interesting and about the NSA...
Unregistered


Donald	Oct 10 2005, 07:56 PM Post #5
Elite member Posts: 454 Group: Trusted Member Member #8 Joined: September 2, 2005	Quote: Digital Fortress Take any cryptography you read about in "Digital Fortress" with a big grain of salt. I haven't read "Digital Fortress" yet, but the cryptographic community has had some pretty bad things to say about it. It may be a good book (I enjoyed "Angels and Demons") but don't trust the crypto. My favorite crypto book is a kids novel: "Alvin's Secret Code" by Clifford B. Hicks. It's a fun story, and you learn basic cryptography along the way. Unfortunantly, you can't get it new anymore, but it's still available on the used market.



rot13	Oct 10 2005, 08:09 PM Post #6
Elite member Posts: 306 Group: Trusted Member Member #14 Joined: September 29, 2005	Donald Oct 10 2005, 07:56 PM Quote: Digital Fortress Take any cryptography you read about in "Digital Fortress" with a big grain of salt. I haven't read "Digital Fortress" yet, but the cryptographic community has had some pretty bad things to say about it. It may be a good book (I enjoyed "Angels and Demons") but don't trust the crypto. I read it, and the crypto is definitely a little off. Overall, the book was good, so if you can ignore the wrong stuff, it is enjoyable. One of the claims of the book is that there is no such thing as an unbreakable cipher, and even presents some fictional law about it. He also gets bits and bytes confused. There was also the suggestion that doubling the number of bits in a key doubles the time it takes to break it. Those are the things that stand out in my memory, it has been over a year since I read it.



cows	Oct 11 2005, 04:45 PM Post #7
Unregistered	i know you just said not to trust it too much - does this include the part about the rotating plain text - making it 'supposedly' impossible to crack - don't believe the impossible part, but what about the rotating part?
Unregistered


Donald	Oct 11 2005, 05:58 PM Post #8
Elite member Posts: 454 Group: Trusted Member Member #8 Joined: September 2, 2005	"cows" what about the rotating part? Ask rot13! <This wikipidia article> explains how rot-13 works. A real cryptographer can probably read rot-13 right off the page. So hopefully Dan Brown was talking about something more complicated than merely rotating text. The only provably unbreakable cipher is a one time pad. And perhaps thats what he was talking about since you can "rotate text" as part of it. You collect an amount of random data that MUST be EQUAL to the length of your message. You use that to encrypt your message, The method of encryption could be xor, or Vigenere style, it doesn't make much difference, just as long as you NEVER EVER EVER reuse the key. Now here, I'll prove that it's unbreakable for you. assume my message was SENDHELP. and my random data was AQZDRGIW, lets use vigenere since I'm doing this by hand (and since Vigenere is "rotating text"): (there is a cute little vigenere applet at http://www.uncg.edu/mat/security/vigenere/vigenere.html that will demonstrate the basic idea of a Vigenere for you, or you can read about it on this board) Code: `sendhelp <-original text AQZDRGIW <-true random key SULGYKTK <-encrypted text (Using Caesar shifts)` so, you find the SULGYKTK code and think you can break it, right? The problem is that it could be decrypted to ANYTHING, depending on what random key I decrypt with. for example: Code: `SULGYKTK <-encrypted text GQISLKIH <-decryption key medonald <-plain text SULGYKTK <-encrypted text KTUSOGLR <-decryption key ibrokeit <-plain text` Because EVERY 8 letter combination is possible, and there is no way to tell which decryption is correct unless you have the original random key. One time pads are absolutely uncrackable and secure. And also so impractical as to be almost useless. Donald



insecure	Oct 11 2005, 08:27 PM Post #9
Elite member Posts: 381 Group: Trusted Member Member #10 Joined: September 9, 2005	Donald Oct 11 2005, 05:58 PM One time pads are absolutely uncrackable and secure. And also so impractical as to be almost useless. When security is the only consideration, and practicality can take a running jump, the one-time pad is still used. For example, the USA used one-time pads during the Cold War, for communications with their embassy in Moscow. I suspect they probably still do, and not just for the Moscow embassy, either. You remember how, on TV news bulletins in the 1970s, when politicians flew to Russia or wherever, you used to sometimes see those guys in suits with the briefcases chained to their wrists? Well, now you should be able to work out what was in the briefcases.



cows	Oct 17 2005, 09:33 AM Post #10
Advanced Member Posts: 91 Group: New Members Member #20 Joined: October 10, 2005	Isn't that mildly stupid having the key chained to your wrist. If anybody wanted it that badly they would surely assasinate the target and the take the case.
	Everything is possible, The impossible just takes longer If we do not know what a particle is doing then it is allowed t do everything possible simultaneously. "Anyone who can contemplate Quantum Mechanics without getting dizzy, didn't understand it."


insecure	Oct 17 2005, 09:37 AM Post #11
Elite member Posts: 381 Group: Trusted Member Member #10 Joined: September 9, 2005	Well, the courier probably isn't too pleased about it, but let's face it - an embassy courier blown away by gunmen whilst on duty might just raise suspicion that the key had been compromised. So it would be a pointless kill



Donald	Oct 17 2005, 01:23 PM Post #12
Elite member Posts: 454 Group: Trusted Member Member #8 Joined: September 2, 2005	"cows" If anybody wanted it that badly they would surely assasinate the target and the take the case. "Insecure" Well, the courier probably isn't too pleased about it But cows has hit upon an important truth. With modern cryptography, it is almost ALWAYS easier to find a weakness in the system then to break the the cipher. And the weakest point of the system is usually the people using it. This was true during WWII as well. The biggest holes in Enigma and Purple were actually lazy soldiers who set keys to their girlfriends names, idiot generals who sent the same messages twice (and often in two different ciphers), and empty headed cipher clerks who transmitted the keys to the new ciphers in the old one. If the NSA wants to read the encrypted messages coming out of the Iran embassy. It's a lot easier (and cheaper) to offer a secretary $100,000 and U.S. Citizenship to hand over the keys than it is to break AES. And it's more likely that the people in the Embassy will do stupid things (like use the same one time pad twice), then that the NSA will find the key through cryptanalysis alone. And actually, that's probably the primary job of NSA cryptanalaysts today. Not to BREAK properly used strong cryptography, but to recognize when human beings have missused it and left the back door open. But hopefully they can find some way more subtle than shooting the courier. That only lets you read ONE message before they change the codes. Donald



cows	Oct 17 2005, 04:06 PM Post #13
Advanced Member Posts: 91 Group: New Members Member #20 Joined: October 10, 2005	Even if it was obvious that you had killed the guy holding the key - you would still have it, and they wouldn't be able to change their code that quickly and we would still ahve all their old messages to crack. Onthe subject of books though - one i heard about - only �10 for a signed copy and comes with a CD full of tools (though you have probably made your own) Anyway it is: The Code Book by Simon Singh found on his website mmm... what you think?
	Everything is possible, The impossible just takes longer If we do not know what a particle is doing then it is allowed t do everything possible simultaneously. "Anyone who can contemplate Quantum Mechanics without getting dizzy, didn't understand it."


Donald	Oct 17 2005, 04:45 PM Post #14
Elite member Posts: 454 Group: Trusted Member Member #8 Joined: September 2, 2005	"cows" you would still have it, and they wouldn't be able to change their code that quickly and we would still ahve all their old messages to crack. Actually, that's what the "one time" in the "one time pad" is about. You only use it one time. SO, shooting a courier carrying the random data for a one time pad would, unless your enemies are complete idiots, probably do you no good at all. You would get the pad that nothing had been encrypted with yet. Since a dead courier will give the embassy a good idea that their pad has been intercepted, they will probably not send a message using that pad. So, all you get is an international incident and no decrypted messages. Donald



insecure	Oct 17 2005, 05:10 PM Post #15
Elite member Posts: 381 Group: Trusted Member Member #10 Joined: September 9, 2005	Donald is of course correct. In any case, these guys with the keys tended to travel along with ambassadors or senior politicians, and a covert kill is pretty tricky in such circumstances. But the important point is that the safe arrival of these keys at the embassy would have to be confirmed (probably using the tail end of the previous pad) before the host nation would encrypt anything through that pad. On cows's other point, Simon Singh's "The Code Book" is well worth the money.



1 user reading this topic (1 Guest and 0 Anonymous)


Go to Next Page
« Previous Topic · Off-topic · Next Topic »

Pages:
1
2
3