Re: [CGA-EXT] CGA-EXT Digest, Vol 47, Issue 2

Hosnieh <ietf@rozanak.com> Mon, 07 January 2013 16:05 UTC

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Date: Mon, 7 Jan 2013 11:05:30 -0500 (EST)
From: Hosnieh <ietf@rozanak.com>
To: "Roque Gagliano (rogaglia)" <rogaglia@cisco.com>
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Subject: Re: [CGA-EXT] CGA-EXT Digest, Vol 47, Issue 2
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Dear Rogue,

Thank you for your comments and questions.



> Why this is an important problem to be addressed is not clear in the text
> other than saying "CGA are computing intensive", which is arguable depending
> on network sizes and equipment



The problem is one of privacy. Addresses need to change in order to protect
privacy. In this vain it then becomes beneficial and important to be able to
generate the IID more quickly. For nodes in the network it is enough to use SSAS
without thinking about the use of certificates because that is all that is
needed to prove address ownership. At the same time, it is recommended to use
vehicles outlined in other RFCs to prevent all nodes from claiming to be a
router.



> You need to add text to the document on where the improvement resides. You
> mentioned something on the answer to Ahmad but that is still not convincing.



So being able to generate the address faster along with reducing the
verification time does not convince you? It is already a given that the use of
CGA for a sec value over 1 is not feasible. Even when using a sec value of 0 the
verification time using CGA is much higher than that for SSAS. The conclusion
drawn from this is that, in the event of DoS attacks, SSAS enable nodes have the
ability to process more packets per minute than do those using CGA.



> You mention that the strength of your algorithm requires that the key pair
> needs to be changed every 2 days. In the case you are using SEND, this means
> generating new certificates for every node every >2 days. This seems like a
> non-starter IMHO



As I explained in my answer to Ray in 6man WG, 2 days is just recommendation. If
one uses 20 days the probability is still low. Now let's explain the problem
from different aspects, i.e., internal network and external network.

Internal network:

We can provide privacy in layer 3. For privacy in layer 2, there is also a need
to have a dynamic MAC address (this is explained in another paper that is under
publication) from which we generate the address by using a kind of hashing
algorithm, like SHA256. This is especially feasible in cloud networks where
virtual machines are used. Using temporary keys and IP addresses would provide
privacy in layer 3.

 We also provide security for this network by preventing DAD and IP stealing
attacks.

One thing that is missing in my draft, which I will correct, is how to avoid
spoofed MAC address attacks. In this case, we also need to include the MAC
address in the signature so that, if the verification process fails, the message
is discarded by the node that should redirect this message.

External network:

Changing router prefixes (now done in some countries) and the IID would provide
the privacy needed for this node in layer 3. But for upper layers, there are a
lot of different approaches available: far too numerous to explain them here.

Another thing is that router nodes do not necessarily require the use of
 certification because, for a node in local network, it is important that they
be able to generate their IP address so that nobody can steal their address and
this is also true routers as well. Finally, the reason for recommending that key
pairs be generated with the generation of a new IP address is that this
eliminates the chance of a node being tracked based on its public key in layer 3
of internal networks and in external networks (eliminates the chance of privacy
attacks).





> Please include the reference to your studies instead of saying "Our
> experimental results show a definite improvement ".



Our research in this area is about to be published. I can upload the results of
our research to our website and refer you to that. (I will add the reference to
the draft after the it published and appears online)



Thank you,

Hosnieh






On January 7, 2013 at 4:40 AM "Roque Gagliano (rogaglia)" <rogaglia@cisco.com>;
wrote:
> Hosnieh,
>
> I have some comments:
> - Why this is an important problem to be addressed is not clear in the text
> other than saying "CGA are computing intensive", which is arguable depending
> on network sizes and equipment
> - You need to add text to the document on where the improvement resides. You
> mentioned something on the answer to Ahmad but that is still not convincing.
> - You mention that the strength of your algorithm requires that the key pair
> needs to be changed every 2 days. In the case you are using SEND, this means
> generating new certificates for every node every 2 days. This seams like a
> non-starter IMHO.
> - Please include the reference to your studies instead of saying "Our
> experimental results show a definite improvement ".
>
> BTW, there other proposals for privacy extensions today that you should
> mention:
> https://tools.ietf.org/html/draft-ietf-6man-stable-privacy-addresses-02
>
> Roque.
>
> On Jan 6, 2013, at 9:40 PM, Hosnieh Rafiee <ietf@rozanak.com>; wrote:
>
> > Dear Ahmad,
> >
> > Thank you so much for your comments.
> >
> >> SEND already offers what you are looking for. It has the Timestamp and the
> > Signature options which are attached to the DNP messages.
> >
> > As I explained in my last email to Jeremy, It just updates SEND and does not
> > replace it. It updates SEND because of the signature contents. I also
> > explained in the draft that we used the same timestamp as is used in SEND.
> >
> >> I agree with the claim that CGA is compute intensive, but one can use Sec=0
> > or 1. In this case the computation of the CGA (SEND) would be equivalent to
> > the complexity of your approach.
> > I compared it with both sec value 0 and sec value 1. I did not consider sec
> > value higher because it is not really feasible in practice that someone wait
> > for 2 or 3 hours to days to generate an address. CGA for 1 it is 600 times
> > more. For zero it is about 10 to 20 times more.
> >
> > The computation of this algorithm is faster than that for CGA and also the
> > verification process is much faster. In the verification process you do not
> > need to do all the CGA generation processing in reverse in order to verify
> > it. With CGA you also have to include the verification time for the
> > signature even though we say we use a sec value of 0 this is not considered
> > in the verification process. For CGA you also need to include an extra 17
> > bytes of options (modifier and collision count) in the packet, but with SSAS
> > the packet size would be less.
> >
> > Thank you,
> > Hosnieh
> >
> > -----Original Message-----
> > From: cga-ext-bounces@ietf.org [mailto:cga-ext-bounces@ietf.org] On Behalf
> > Of cga-ext-request@ietf.org
> > Sent: Sunday, January 06, 2013 9:10 PM
> > To: cga-ext@ietf.org
> > Subject: CGA-EXT Digest, Vol 47, Issue 2
> >
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> > Today's Topics:
> >
> > 1. Re: Call for comments on draft-rafiee-6man-ssas-00.txt
> > (Al-Sadeh, Ahmad)
> >
> >
> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Sun, 6 Jan 2013 21:09:53 +0100
> > From: "Al-Sadeh, Ahmad" <Ahmad.AlSadeh@hpi.uni-potsdam.de>;
> > To: Hosnieh Rafiee <ietf@rozanak.com>;, "cga-ext@ietf.org";
> > <cga-ext@ietf.org>;
> > Cc: "ipv6@ietf.org"; <ipv6@ietf.org>;
> > Subject: Re: [CGA-EXT] Call for comments on
> > draft-rafiee-6man-ssas-00.txt
> > Message-ID: <BB4E1F8A-2971-4648-82E4-3A34DBE777A5@mimectl>
> > Content-Type: text/plain; charset="Windows-1252"
> >
> > Hosnieh,
> > I have read your draft. And I have the following comments.
> > SEND already offers what you are looking for. It has the Timestamp and the
> > Signature options which are attached to the DNP messages. So, the new
> > benefits of your approach are not clear to me.
> > I agree with the claim that CGA is compute intensive, but one can use Sec=0
> > or 1. In this case the computation of the CGA (SEND) would be equivalent to
> > the complexity of your approach. Therefore the enhancements that are
> > proposed to protect the user privacy by setting a lifetime for the generated
> > address (e.g. 2 days) or generating the key pairs by CGA code can be
> > directly applied to the CGA and SEND implementation without significant
> > change to proposed standard.
> > In Section 5, ?? it provides proof of address ownership at a speed that is
> > about 600 times faster than that of the CGA algorithm.?
> > For which Sec value this comparison was done?
> > Regards,
> > Ahmad AlSadeh
> >
> > ________________________________
> > From: cga-ext-bounces@ietf.org [cga-ext-bounces@ietf.org] On Behalf Of
> > Hosnieh Rafiee [ietf@rozanak.com]
> > Sent: 04 January 2013 21:13
> > To: cga-ext@ietf.org
> > Subject: [CGA-EXT] Call for comments on draft-rafiee-6man-ssas-00.txt
> >
> >
> > Dear All,
> >
> > This draft addresses the following problem:
> > Unfortunately the existing drafts do not consider the integration of
> > security and privacy for the generation of the Interface ID (IID). This
> > draft tries to offer a solution to this problem while at the same time
> > considering the generation and verification times and complexity of the
> > existing algorithms. Please take a look. Comments are greatly appreciated.
> > Thank you,
> > Hosnieh
> >
> >
> >
> > Filename: draft-rafiee-6man-ssas
> > Revision: 00
> > Title: A Simple Secure Addressing Generation Scheme for IPv6
> > AutoConfiguration (SSAS)
> > Creation date: 2013-01-02
> > WG ID: Individual Submission
> > Number of pages: 13
> > URL:
> > http://www.ietf.org/internet-drafts/draft-rafiee-6man-ssas-00.txt
> > Status: http://datatracker.ietf.org/doc/draft-rafiee-6man-ssas
> > Htmlized: http://tools.ietf.org/html/draft-rafiee-6man-ssas-00
> >
> >
> > Abstract:
> > The default method for IPv6 address generation uses two unique
> > manufacturer IDs that are assigned by the IEEE Standards Association
> > [1] (section 2.5.1 RFC-4291) [RFC4291]. This means that a node will
> > always have the same Interface ID (IID) whenever it connects to a new
> > network. Because the node's IP address does not change, the node is
> > vulnerable to privacy related attacks. To address this issue, there
> > are currently two mechanisms in use to randomize the IID,
> > Cryptographically Generated Addresses (CGA) [RFC3972] and Privacy
> > Extension [RFC4941]. The problem with the former approach is the
> > computational cost involved for the IID generation. The problem with
> > the latter approach is that it lacks security. This document offers a
> > new algorithm for use in the generation of the IID while, at the same
> > time, securing the node against some types of attack, such as IP
> > spoofing. These attacks are prevented with the addition of a
> > signature to the Neighbor Discovery messages (NDP).
> >
> >
> > --------------------------------------------------------------------
> > IETF IPv6 working group mailing list
> > ipv6@ietf.org
> > Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6
> > --------------------------------------------------------------------
> >
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> > End of CGA-EXT Digest, Vol 47, Issue 2
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