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06:40
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Q: Finding CRC collisions for specific divisor

BSchlinkerMy current textbook (Information Security: Principles and Practice by Mark Stamp) discusses how to determine the CRC of data via long-division, using XOR instead of subtraction to determine the remainder. If our divisor has N-bits, we append (N-1) 0 bits to the dividend (the data) and then use l...

 
13 hours later…
19:36
Hi guys if you're here, I'm running slightly late, feel free to start.
I will catch up shortly :)
19:51
Right, I'm here
My apologise, please feel free to blame the trains in the UK :(
So, who've we got :)
?
Well, you have little ol' me
an' me
dunno how much use I am though but thought I'd say hi:-)
@poncho It might just be us :( Ok, In a sec, I'll start as I have a book I've been reading and either of @poncho or @rory can fire away if they've got a book to talk about. If nobody joins us, we'll just do a free for all ask about what crypto books you've read
Heh - I think I've only read 2 proper Crypto books ever. The Handbook of Applied Cryptography and Practical Cryptography
@RoryAlsop Well in a bit feel free to stick some thoughts down here in chat :)
19:57
And both outstripped my maths before the end :-(
I've read considerably more, but nothing that recently
Ok, well we'll see how we do :)
(both of those were some years ago.....)
Right, I've been reading this little number:
So - this covers just about everything you could want to know on ECC, including implementation. It starts off with a very brief introduction to fields of small characteristic and arthmetic on elliptic curves, then plunges straight into Efficient Implementation - i.e. point compression. From there, you start reading about the MOV attack, Schoofs algorithm etc.
I am personally about 3/4 of the way through.
Hmmm, I don't believe I've seen that one. On EC references, I've got the Frey et al (Handbook of Elliptic and Hyperelliptic Curve Cryptography), and Washington (Elliptic Curves/Number Theory and Cryptography)
20:01
Now, it's very thorough, but it's very mathematical. The introductory sections are very very brief overviews of the arithmetic of elliptic curves, so if you're not familiar with that (like me) you either need another book, or the patience to google.
So, what do you think of the Blake? The ones I've read have been more about the mathematics behind Elliptic Curves, and less (hardly much at all) about the cryptography
@poncho This is very mathematically-inclined. There are some algorithms presented, but only in very pure form. There are, in this book, a few notes on efficiency
which my programmer brain is able to interpret, but it isn't a "how to implement" book by any means.
I am definitely enjoying it and thinking it's a good read, but if you want an intro reference I might find something else, likewise for a "how to implement".
Actually, I don't care that much about "how to implement". What I'm interested in is answers to security related questions; "what do you need to avoid"
As for an intro text, I believe I already have a basic understanding
@poncho It's pretty light in that area through. Just had a thumb through to check and it focuses a lot on the maths/algorithms. It reminds me of reading about "theoretical" RSA in a number theory textbook as opposed to reading PKCS#1. Obviously, it covers the MOV attack so it does have some things to avoid when searching for good curves.
So that's my book :) Any questions I can try to answer, or we can talk about some others?
Sounds like it's not that much of a step up over what I already have (I don't believe they cover MOV, or searching for a good curve, so if I ever need to do that, I might get it; I don't anticipate needing that, though...)
Hmmmm, how much does it go into IBE?
20:13
@poncho So what do you make of the handbook of elliptic curve... book? I looked at that when wondering what to buy; in th eend I got this one from the library.
@poncho Not at all.
Oh no wait a sec
Well, it rather depends on what you're looking for. If you're looking for something that talks about the mathematics behind elliptic curves, it goes through that rather extensively. If we're talking about the cryptography, well, it does, but (IMHO) in rather less depth
Ok so on IBE, it covers weil pairings and related mathematics but makes no specific mention of IBE
@poncho Ah ok, interesting - I assume the number theory one is similar then?
For example, ECDSA is essentially one of the two most commonly used EC crypto primitives (the other one is ECDH); the ECDSA algorithm is discussed on one page (without any discussion of, say, what happens if the signer doesn't choose r uniformly (or even, as far as I can see, that using r for two different signatures is a bad idea)
Yes, the Washington is even worse (to the point I almost suspect that the publisher put in the "and Cryptography" mostly to make it sell more)
@poncho Oh dear :( Ok, one to avoid then!
Ok, maybe it's not that bad... but, there's no reason to search it out either.
20:23
Fair enough - so, @poncho, any other books you want to bring up?
Hmmmm, I didn't have anything in particular in mind; as I mentioned, I haven't been reading many crypto books (not counting things I needed to look up references in)
Ok, well I've read another one. This one was a while ago, and I felt was pretty light on detail really. It dealt with basic DH and RSA, but again, missing the critical crypto elements (like RSA padding). It covers EC, but in no way near as much depth as the green book above:
It is an undergraduate text, so I suppose as an intro reference it is fine (fairly easy to read etc), I just felt like when I'd done I'd already covered what I knew.
Whilst we're here too, I have also looked at this:
I struggled to find any books covering cryptanalysis at all - this one does and is my next to-read. I am yet to sit down with it, but it looks quite comprehensive, so I'm looking forward to it.
Has anyone read it?
Sorry, I haven't.
It does look interesting, though...
And, yes, books covering cryptanalysis are quite hard to find
I found one other, actually, I don't have a link to hand, but it had next to nothing in it.
Not even a mention from the amazon preview of differential or linear cryptanalysis (which the above has) or pollard's rho (which I have yet to study). When I sit down with it (and for next time) I'll be able to talk all about it; but this one looked much more promising than the other.
I just glanced through the table of contents on the Swenson; it sounds like it covers the basics (up to LC/DC); that's good, but it doesn't go much beyond that.
20:34
I think this one might need to go with it:
It also has worked examples in C, which is more up my street (it's not the one I was referring to).
(Which I can't find).
Right, @RoryAlsop, from an intro perspective do you want to cover HOAC etc ?
@Ninefingers you have already scared me!
Practical Crypto is probably well below anything you guys would ever read
Hmmm, well, the Joux is a lot pricier, and it doesn't appear to cover LC/DC; it does appear to cover correlation attacks (useful against LFSR-based stream ciphers), as well as Coppersmith's attack against partially revealed RSA keys. Those attacks would appear to be less generic; my advice (if you had to pick one) would be to go with the Swenson
and the HOAC is relatively functional but relies on the reader having a reasonable grasp of the maths already
Actually, "Practical Crypto" is exactly that; it doesn't worry about the theoretical aspects of crypto (that we like to talk about, because they're neat and tidy), but "how do you do crypto that's actually secure in the real world".
There's quite of bit of "social" aspects to cryptography that we tend to ignore, but are practically imortent
That one? (I'm just pasting in Amazon links, by the way - it does the big box thing, no special magic). I've not read that - but it sounds like it covers a more security-practicalities focused view on crypto?
So as it's quiet I'll mention two others that come up a bit:
20:43
@Ninefingers yes it was that one - had to go and get it out to look at the cover
So on Applied crypto - these days I think it's fair to say it's showing its age, but when I read it (not so long ago, actually) it covers implementing in C many different algorithms in a very thorough way.
The other intro reference that gets mentioned is this:
Which is available here: cacr.uwaterloo.ca/hac
AC is (IMHO) the book that both helped the most in crypto, and caused the most damage. It helped the most because it attacted so many people to learn more about cryptography. It did the most damage because so many people just read it, and figured they knew enough...
@poncho That sounds pretty accurate - it's fair to say having participated here my eyes have been opened, so it's a good introductory reference but definitely not a complete, all inclusive guide.
On HOAC - I think again that's a very thorough introductory reference - again slightly dated, but still useful.
I am personally not that thrilled with HOAC as an intro text; it seemed to me more geared to give description of algorithms, with not enough detail about what the algorithms are meant to do. I think it's rather more important to stress the "why" and less the "what".
@poncho I've always sort of used it as a "I need to know how to do X - look up such a chapter" - I feel it's more that kind of book. I'd honestly say the whys I've picked up more as I've come here and from reading online previous to crypto.se starting than from any of the intro books.
Is there an intro book that covers the why, do we know?
21:01
Hmmm, I'm not sure; I don't read that many intro books (unless I'm deliberately reseaching somthing I didn't know before, such as EC).
@poncho mmm ok.
Right, anyone anything else they want to add? Any questions anyone wants to ask, whilst I'm here?
Right, well I think we'll call that an end :) Thanks for coming along @Rory, @poncho, I'll organise another one in the next week or so for a month's time (ish) :) Feel free to check meta where they get posted and comment if the date/time is problematic.
cheers @Ninefingers - was good to see what gets talked about on this, sorry it's not my area of expertise though
Also, if anyone wants a chat event on a specific topic, feel free. It doesn't have to be me who organises it - anyone can :)
And now it's been bookmarked:

Chat event #3 - book discussion featuring Poncho, Rory Alsop and Ninefingers

2 hours ago, 1 hour 36 minutes total – 89 messages, 3 users, 0 stars

Bookmarked 22 secs ago by Ninefingers

How do you bookmark?
21:16
@RoryAlsop Room > create new bookmark. Anyone can, no need to be a room owner or mod.
Select a starting and ending message and it forms a bookmarked page in the room's "conversations" tab.
ahh - never seen that before. thanks
We've a few on the DMZ - Jeff Ferland has been busy :)
One of mine with this.josh:

L4 and capabilities

Nov 26 '11 at 4:43, 1 hour 32 minutes total – 69 messages, 2 users, 0 stars

Bookmarked Nov 26 '11 at 6:31 by Ninefingers

Where can you find existing bookmarks?
this is all very new and confusing - I obviously need to click on things more
can't see link to existing bookmarks, though
@RoryAlsop if you click info and get the room page up - there's a "conversations" tab in there
should list them all :)
heh - another page I have never seen. I seem to recall clicking on info a year ago and not getting anything coming up so I never usd it again
21:22
@RoryAlsop Useful in TL to find some of the discussions that have taken place. Not all of them are sensible ones though :(
hahahaha - every time I have needed to find one so far I have asked about it and someone magically gave me a link. I assumed they had some tool, but didn't realise I could see it too
@RoryAlsop I've no idea how they do it so fast - I do know roughly where to look though.
Ah, sorry everyone, I missed the chat meeting :-(
Well, I suppose you'll need to bring donuts to the next one :-)
I could have come (I was at the computer the whole time, writing unit tests), but I somehow totally forgot it.
But I didn't prepare any review anyways (no time).
21:30
I'd like to put my donut order in. One like this please ;)
@Ninefingers I did read this one (Blake: Elliptic Curves in Cryptography), too, some months ago (after it was mentioned here). Your impression fits mine quite nice.
@PaŭloEbermann No probs, it's not the end of the world, we had a nice chat anyway I think, but it would be nice to hear about that Rijndael/AES book you've been reading at some point.
Okay, I'll write up a bit for the next time.
(I think I'll have to put the chat meetings in all my Google calendars, both the private and the work one, to minimize the chance of missing a meeting. Just the e-Mail reminder and the popup from the site some minutes ago are not enough.)
@PaŭloEbermann there's an iCal link you can use - chat.stackexchange.com/rooms/schedule/export/784/all
I'm hoping things like that are fed into the community calendar idea Shog9 had.
@Ninefingers Ah, thanks.
Adding this now.
21:43
If google calendar ever falls apart my life will be one huge disorganised mess!
22:00
Okay, everything committed, and even Jenkins did accept it ... so I'm going home now. Good night everyone.
G' night!

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