I'm just reading this:

http://www.sans.org/reading_room/whitepapers/vpns/1459.php

I few "interesting" things about this document. (E.g., there's a section 
called "what the heck is IPSec?" That's very whitty, but I'm not sure 
how seriously you should trust such a document...)

The basic premise seems to be that all VPN systems currently in 
existence actually suck, except OpenVPN which is completely perfect. A 
suspicious conclusion, obviously.

The document claims this is because "IPSec is too complicated to be 
secure", and that "TSL is mature and battle-tested". It also asserts 
that running software in user-space is inherantly better from a security 
perspective. (While it *is* better, it's hardly the end of the story...)

The document seems to indicate that installing IPSec VPN software on 
Windows is excrusiatingly difficult due to the built-in IPSec 
functionallity Windows already has. (...is does??) For example,

"On Windows, OpenVPN installs just like any other program. It comes 
bundled up as an executable and all you need to do it double click on 
the installer. Total installation of the Windows client takes about 10
minutes including configuration. For anyone who has tried to configure 
the builtin Windows IPSec client that should be impressive. For people 
who have tried to install and configure third party IPSec clients, that 
number should be shocking!"

Um... am I missing something? Installing Cisco's IPSec VPN involves... 
double-clicking the installer. And that's it. What's so hard about that?

Also amusing is the statement "Blowfish is a very strong algorithm with 
no known weaknesses. Its 128-bit key provides us with a large enough key 
space to make brute force key attacks impossible in polynomial time." 
Erm... like... WTF?

Still, I did learn one useful thing: Apparently the "route" command 
exists on Windoze.

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Weeeee....

http://eprint.iacr.org/2008/166.pdf

There's nothing like cryptanalysis to make you paranoid! ;-)

-- 
http://blog.orphi.me.uk/
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Ooo, shiny...

http://orion.math.iastate.edu/dept/thesisarchive/MS/EKleimanMSSS05.pdf

Anybody know what a "null space" is?

(Better yet - anybody know of a job where knowing this kind of thing is 
actually an advantage?)

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http://blog.orphi.me.uk/
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Invisible wrote:
> The document claims this is because "IPSec is too complicated to be 
> secure", and that "TSL is mature and battle-tested".

I like how they make this assertion, then later on say "you might need 
the load balancing that IPsec does, but you can get that with OpenVPN by 
running this other complicated program on a spare machine." It sounds 
like a lot of the complication is stuff that OpenVPN basically leaves out.

Plus, I'm not really sure how they're running TLS over UDP, given that 
TLS is stream-oriented and assumes reliable delivery. It's also not real 
obvious from their descriptions that it's possible to run a UDP protocol 
over OpenVPN.

> Um... am I missing something? Installing Cisco's IPSec VPN involves... 
> double-clicking the installer. And that's it. What's so hard about that?

Ditto.

> Also amusing is the statement "Blowfish is a very strong algorithm with 
> no known weaknesses. Its 128-bit key provides us with a large enough key 
> space to make brute force key attacks impossible in polynomial time." 
> Erm... like... WTF?

Of course, it hasn't been tested as furiously as AES, either.

> Still, I did learn one useful thing: Apparently the "route" command 
> exists on Windoze.

Yup.
http://technet2.microsoft.com/WindowsServer/en/library/552ed70a-208d-48c4-8da8-2e27b530eac71033.mspx?mfr=true
Might be worth reading thru the list so you know what's available.

-- 
Darren New / San Diego, CA, USA (PST)
  Helpful housekeeping hints:
   Check your feather pillows for holes
    before putting them in the washing machine.

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>> The document claims this is because "IPSec is too complicated to be 
>> secure", and that "TSL is mature and battle-tested".
> 
> I like how they make this assertion, then later on say "you might need 
> the load balancing that IPsec does, but you can get that with OpenVPN by 
> running this other complicated program on a spare machine." It sounds 
> like a lot of the complication is stuff that OpenVPN basically leaves out.

Well, is that a protocol feature or a software feature?

> Plus, I'm not really sure how they're running TLS over UDP, given that 
> TLS is stream-oriented and assumes reliable delivery. It's also not real 
> obvious from their descriptions that it's possible to run a UDP protocol 
> over OpenVPN.

Hmm, that's a good point.

>> Also amusing is the statement "Blowfish is a very strong algorithm 
>> with no known weaknesses. Its 128-bit key provides us with a large 
>> enough key space to make brute force key attacks impossible in 
>> polynomial time." Erm... like... WTF?
> 
> Of course, it hasn't been tested as furiously as AES, either.

I was more amused by the statement that key size has any relationship to 
complexity class.

Blowfish is far more popular than, say, TEA or SQUARE or any number of 
other ciphers from the zoo of less-known algorithms out there. I note 
however that Blowfish has been "replaced" by Twofish which is meant to 
be stronger. (And AES finalist, I believe.)

A lot of people are apparently jumpy about the whole XSL attack thing on 
AES.


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Orchid XP v8 wrote:
>>> The document claims this is because "IPSec is too complicated to be 
>>> secure", and that "TSL is mature and battle-tested".
>>
>> I like how they make this assertion, then later on say "you might need 
>> the load balancing that IPsec does, but you can get that with OpenVPN 
>> by running this other complicated program on a spare machine." It 
>> sounds like a lot of the complication is stuff that OpenVPN basically 
>> leaves out.
> 
> Well, is that a protocol feature or a software feature?

I'm saying that they mock IPsec for solving problems *they* don't have, 
because it was "designed by a committee".  I suspect the people on the 
"committee" actually *did* have those problems, so incorporated 
solutions to them into the standard, instead of making everyone solve it 
themselves with ad hoc solutions consisting of interacting layers which 
could easily introduce a security hole if you don't know what you're doing.

> I was more amused by the statement that key size has any relationship to 
> complexity class.

Yes, I understood the WTF. :-) Of course, if it's running over TLS, you 
can put whatever cipher both sides agree on in there.

And actually, key size *can* have a relationship to complexity class, 
perhaps. If you can pre-compute something that lets you look up in 
polynomial time the key that someone is using, except that the key is 
too long to store the precomputed somethings for every key, I can see 
where that can happen. (Technically, the same complexity class, but in 
practice, you can break something in polynomial time if you discount the 
precomputation, perhaps.)

But yeah, the whole discussion was full of WTFs like that. Plus, they 
say basically "IPSec is too complicated to deploy, OpenVPN does the same 
thing only its easy to deploy", without giving any evidence at all of 
either. Most of the paper is a description of SSL, and I'm pretty sure 
there aren't fundamental security problems with IPSec that aren't in SSL.

(And apparently the authors don't know that actual difference between 
SSL and TLS.  Hint: OpenVPN seems to use SSL.)

-- 
Darren New / San Diego, CA, USA (PST)
  Helpful housekeeping hints:
   Check your feather pillows for holes
    before putting them in the washing machine.

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Darren New wrote:

> But yeah, the whole discussion was full of WTFs like that. Plus, they 
> say basically "IPSec is too complicated to deploy, OpenVPN does the same 
> thing only its easy to deploy", without giving any evidence at all of 
> either. Most of the paper is a description of SSL, and I'm pretty sure 
> there aren't fundamental security problems with IPSec that aren't in SSL.
> 
> (And apparently the authors don't know that actual difference between 
> SSL and TLS.  Hint: OpenVPN seems to use SSL.)

Hmm. I just wanted to know whether this piece of software was worth using.

I think I have my answer now...

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Orchid XP v8 wrote:
> Hmm. I just wanted to know whether this piece of software was worth using.
> I think I have my answer now...

Oh. I imagine if it solves the problem you have, it's probably worth 
using, assuming you can get it working and it's sufficiently widespread 
you trust it.

That the people writing the *paper* didn't write it in a convincing way 
doesn't really say much about the *code*.

-- 
Darren New / San Diego, CA, USA (PST)
  Helpful housekeeping hints:
   Check your feather pillows for holes
    before putting them in the washing machine.

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Invisible wrote:
> Weeeee....
> 
> http://eprint.iacr.org/2008/166.pdf
> 
> There's nothing like cryptanalysis to make you paranoid! ;-)
> 
It lead to a discussion in parliament here and a bad time for one of our 
ministers. Introduction of the country-wide OV chipcard (OV is the 
abbreviation for public transport) is postponed now.

At the last election in some cities voting was done again by paper and 
red pencil because somebody showed that you could listen to what people 
voted by putting a radio receiver close to it and a few more 
insecurities of the digital voting machines.

What these examples have in common is that they were badly designed and 
they relied on people not knowing the details as an important security 
measure. The latter is of course an absolute sin in cryptography, but 
apparently not (yet) when designing voting equipment or identification 
cards.

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andrel wrote:

> What these examples have in common is that they were badly designed and 
> they relied on people not knowing the details as an important security 
> measure. The latter is of course an absolute sin in cryptography, but 
> apparently not (yet) when designing voting equipment or identification 
> cards.

Security through obscurity = hmm, it doesn't work. ;-)

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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