Subject: RE: [Mip6] Security Section Comments ondraft-ietf-mip6-bootstrap-ps-01.txt

From: [email-masked]
Date: Wed, 23 Feb 2005 07:23:16 +0200

Hi James,

> Actually, I think we want to keep the keys separate even if the network
> access provider and mobility service provider are the same. From a security
> standpoint, it makes sense to maintain separate keys, so that if one is
> compromised the other won't be.  I suppose one could argue that "well, if
> the network access service is compromised, the user is so hosed, so it
> really doesn't matter if mobility service is compromised" but the othe way
> around is something different. If the mobility service key is compromised,
> the mobile host could stay put at the same place and re-establish secure
> mobility access service, as long as network access service is not
> compromised. If the two keys are the same, then the mobile host must go
> through re-establishing secure network access service before mobility
> service security can be repaired.
> 
> Does this make sense? If so, perhaps the draft should make this point
> explicitly.

I think we should make this point explicitly.  To modify your proposed text:

>> In addition to these attacks, there are other considerations that are
>> important in achieving a good security design. Because mobility and network
>> access authentication are separate services, any keys for these services
>> need to be cryptographically separate, separately named, and have separate
>> lifetimes that are not exceeded. This is necessary because a mobile host
>> must be able to move from one serving (or roaming) network access provider
>> to another without needing to change its mobility access provider. Finally,
>> basic cryptographic processes must provide for multiple algorithms in order
>> to accommodate the widely varying deployment needs.

 In addition to these attackes, there are other considerstions that are important
 in achieving a good security design. As mobility and network access authentication
 are seperate services, keys for these services need to be cryptographically 
 seperate, seperately named and have seperate lifetimes. This is needed because
 if one service is compromised, the other service is not. This is necessary 
 so that a mobile host can move from one serving (or roaming) network access 
 provider to another without needing to change its mobility access provider. 
 Finally, basic cryptographic processes must provide for multiple algorithms in order
 to accommodate the widely varying deployment needs.

John

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From: "James Kempf" <[email-masked]>
Date: Wed, 23 Feb 2005 08:39:27 -0800

Sounds fine.

            jak

----- Original Message ----- 
From: <[email-masked]>
To: <[email-masked]>; <[email-masked]>
Sent: Tuesday, February 22, 2005 9:23 PM
Subject: RE: [Mip6] Security Section Comments
ondraft-ietf-mip6-bootstrap-ps-01.txt

Hi James,

>> to accommodate the widely varying deployment needs.

 In addition to these attackes, there are other considerstions that are
important
 in achieving a good security design. As mobility and network access
authentication
 are seperate services, keys for these services need to be cryptographically
 seperate, seperately named and have seperate lifetimes. This is needed
because
 if one service is compromised, the other service is not. This is necessary
 so that a mobile host can move from one serving (or roaming) network access
 provider to another without needing to change its mobility access provider.
 Finally, basic cryptographic processes must provide for multiple algorithms
in order
 to accommodate the widely varying deployment needs.

John

---

From: Yoshihiro Ohba <[email-masked]>
Date: Wed, 23 Feb 2005 19:41:58 -0500

Hi John and James,

I think that we might define which level of the keys for the two
services in the EAP key hierarchy needs to be cryptographically
separated (for simplicity let me assume that the keys are part 
of EAP key hierarchy).

It is always good to cryptographically separate keys derived from the
EAP MK (Master Key) for network access service and keys derived from
the EAP MK for mobility service.  On the other hand, depending on
optimization level and deployment scneario, two EAP MKs may be the
same, meaning that cryptographic separation may not always be possible
at the highest level of the EAP key hierarchy.

Yoshihiro Ohba

---

From: "James Kempf" <[email-masked]>
Date: Thu, 24 Feb 2005 10:42:25 -0800

Yoshi,

This works if EAP is used, but it might not be. From the perspective of the
problem statement, I think it is sufficient to state that the keys need to
be cryptographically separated. In the solutions document, this then can be
addressed in a way appropriate to the solution.

            jak

----- Original Message ----- 
From: "Yoshihiro Ohba" <[email-masked]>
To: <[email-masked]>
Cc: <[email-masked]>; <[email-masked]>
Sent: Wednesday, February 23, 2005 4:41 PM
Subject: Re: [Mip6] Security Section Comments

important
authentication
because