Re: [P2PSIP] Identity certificate segregation [was Re: draft-ietf-p2psip-base publication to be requested]

[Marc Petit-Huguenin <[e-mail]>]

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On 07/02/2011 09:28 AM, Diego Suarez wrote:
> Hi,
> 
>>From my point of view, in this case the user has to both prove she is in
> possession of the PKC that includes the required username and also prove
> she is operating from the required node. However, modifying the
> SignerIdentity to include multiple identities ( the user and the
> device ) would not really prove that since only one signature could be
> included (either the user's signature or the device's one). 
> 
> Therefore, I'd modify the SecurityBlock instead to allow the inclusion
> of more than only one signature. 
> 
> For this case, the securityBlock would include two signatures. One with
> the SignerIdentity of the user and the signature of the user's PKC
> (including the username ) and another with the SignerIdentity of the
> device and the signature of the device's PKC ( including the nodeID).

Right, something like this:

struct {
   GenericCertificate certificates<0..2^16-1>;
   Signature          signatures<0..2^16-1>;
   } SecurityBlock;

Note that StoredData also needs to be modified:

struct {
   uint32          length;
   uint64          storage_time;
   uint32          lifetime;
   StoredDataValue value;
   Signature       signatures<0..2^16-1>;
   } StoredData;

> 
> cheers
> 
> 
> On Fri, 2011-07-01 at 15:44 -0700, Marc Petit-Huguenin wrote:
> Hi Diego,
> 
> How does this work with an access control policy like USER-NODE-MATCH, which
> requires both a Node-ID and a username in the SignerIdentity?  If the Node-ID
> and the username are in separate certificates, wouldn't that require to extend
> the SignerIdentity structure to store multiple identities?
> 
> Thanks.
> 
> On 06/09/2011 10:47 AM, Diego Suarez wrote:
>>>> I think it would require a (slight) modification in the base document.
>>>> Current P2PSIP certification model is based on a single PKC (including
>>>> both usernames and nodeIDs) that uniquely identifies a user and her
>>>> devices. On the other hand, our model is base on a split certification.
>>>> Devices and users are independent. Each device has its own PKC including
>>>> a nodeID and a PK. Similarly, each user has her own PKC including her
>>>> username and a PK. This approach do not prevent a centralized entity
>>>> (such as an offline CA) to have information related to the devices each
>>>> user (or company, etc.) has registered, but permits, among other
>>>> improvements, a user to be connected to the system through devices she
>>>> has not registered herself such as a phone issued by a telco or a fixed
>>>> phone in a laboratory shared by all the members of a research group.
>>>>
>>>>
>>>> On Thu, 2011-06-09 at 10:05 -0700, Marc Petit-Huguenin wrote:
>>>> Does this model really required modifications in the base document, or can it be
>>>> designed as an extension?  (Unfortunately the paper is not freely available, so
>>>> it is difficult to know really what is needed for this).
>>>>
>>>> On 06/09/2011 07:31 AM, Diego Suarez wrote:
>>>>>>> Hi, 
>>>>>>>
>>>>>>> I had in mind writing a draft about this, but since I'm running out of
>>>>>>> time, I would like to summarize a new certification model for P2PSIP I
>>>>>>> have been working on, in case it is of interest for the group.
>>>>>>> Further details can be found in paper:
>>>>>>>
>>>>>>> D. Touceda, J. Camara, L. Villalba, and J. Marquez, Advantages of
>>>>>>> identity certificate segregation in P2PSIP systems, Communications,
>>>>>>> IET, vol. 5, pp. 879889, Apr. 2011.
>>>>>>>
>>>>>>>
>>>>>>> The idea is to split the certification of users and devices. Devices are
>>>>>>> identified by PKCs including a nodeID and the PK of the device, while
>>>>>>> users are identified by PKCs including a username and the PK of the
>>>>>>> user. Similar models have been used before in other communications
>>>>>>> systems, such as GSM where devices and users are separately represented
>>>>>>> by the international mobile equipment identity (IMEI) stored in the
>>>>>>> phones and the international mobile subscriber identity (IMSI) stored in
>>>>>>> the user subscriber identity module (SIM), respectively.
>>>>>>>
>>>>>>> Motivations of this model are:
>>>>>>>
>>>>>>> - Users and devices are different entities performing different
>>>>>>> roles within a P2PSIP system. Devices are nodes of the P2P
>>>>>>> overlay network (represented by a nodeID) that offer services
>>>>>>> (to route messages, to store data, . . .) to the system, while
>>>>>>> users (represented by an username) utilize these services,
>>>>>>> usually to establish media communications using SIP.
>>>>>>>
>>>>>>> - Support for mobility scenarios where a user may be logged at different
>>>>>>> devices at the same time using the same PKC.
>>>>>>>
>>>>>>> - Support several users to be logged in the same device (like a fixed
>>>>>>> phone) at the same time.
>>>>>>>
>>>>>>> - Support for user independent hard-coded devices.
>>>>>>>
>>>>>>> - Interoperability with SIP. SIP certificates are not valid in actual
>>>>>>> P2PSIP since they don't include a nodeID.
>>>>>>>
>>>>>>> cheers
>>>>>>>
>>>>>>> Diego Suárez
>>>>>>>
>>>>>>>
>>>>>>> On Wed, 2011-06-08 at 09:48 -0700, David A. Bryan wrote:
>>>>>>>> Unless something major comes up, we plan to request the newest version
>>>>>>>> of the base draft, draft-ietf-p2psip-base-15, be published. I'll put
>>>>>>>> in the request in a week (June 16th or 17th). If there are any further
>>>>>>>> comments from the last call a while ago (or further comments on the
>>>>>>>> comments since then), please send them to the list ASAP.
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>>
>>>>>>>> David (as chair)

- -- 
Marc Petit-Huguenin
Personal email: [e-mail]
Professional email: [e-mail]
Blog: http://blog.marc.petit-huguenin.org
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