Internet-Draft Pars Mutaf Expires: July, 2007 Institut National des Telecommunications Evry, France January, 2007 Private Information Queries (Problem statement) Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Abstract This document makes a problem statement for the "Private Information Queries" protocol. Mutaf Expires July, 2007 [Page 1] Internet-Draft PIQ problem statement January 2007 1. Introduction By current practice, for privacy reasons, cellular phone numbers are not made publicly available nor predictable (this is also suggested in [SIPPRI]). Today, cellular users are obligated to manually share their phone numbers with their colleagues, friends, family members, etc., through face-to-face communication (i.e. oral communication). This is unfortunate. Some wireless technologies e.g. Bluetooth or IrDA can allow for sharing a phone number and other information in a more convenient way. Nevertheless, these technologies operate over very short distances, hence also require user contact. It is very desirable to have a protocol that allows for sharing phone numbers, or other private information over much longer distances. There is also anecdotal evidence that users often loose the list of their correspondents accidentally upon loss of state, or when their cellular device is lost/stolen/changed. Recovering the list of correspondents is very difficult for the same reasons described above. 2. Private information queries Private information queries is an application-layer IP protocol. It can be used to request private information *directly* from the target user's device. It is an Internet protocol, consequently it is possible to request the phone number of a user, via a cellular network i.e. over a very large distance. Figure 1 illustrates the basic protocol operation: Cellular host Cellular host (John Hoffman) (Alice Collins) 1. ------ Request(phone number)------> 2. user approval 3. <----- Response(phone number)------ Figure 1. Private information request/response The request is sent directly to Alice Collins's host's IP address. Upon receipt of the private information request, the responder application displays a message: John Hoffman requested your phone number. Do you wish to return it? [YES/NO] If approved by the user, the responder application returns the requested information. The target user may know John Hoffman and may accept the request. Or, the target user may not know John Hoffman but may have an idea who he is and/or why he is trying to contact, and hence may accept the request (or not). The decision belongs to the target user. It is taken in real-time. Mutaf Expires July, 2007 [Page 2] Internet-Draft PIQ problem statement January 2007 3. Example solution: multicast name resolution How one can get the IP address a phone, if that phone's SIP URI is unknown? A solution can be built on top of multicast name resolution [MNR] or an improved version of it. Although this protocol is currently limited to link-local scope, within a wireless access subnet that covers a large number of cells, one can reach a user over very large distances. This is already an important progress compared to using a short-range wireless technology e.g. Bluetooth (current practice). In this approach, the responder configures a name from the user's human name, for example "alicecollins". The requester user will enter the name Alice Collins, and the application will trigger a multicast name resolution request to the name "alicecollins". The request will be multicast over the subnet, and the target host will return an IP address. At this point, the requester application can send a private information query to the destination user's host. The target user's phone number can be obtained (if accepted by the target user). Next time, the target user can be contacted using his/her phone number i.e. regardless of location. 4. Security considerations The requester's identity (found in the request message) must be authenticated. Public key cryptography and certificates may be used to address this problem. The responder's identity (found in the response message) must be also authenticated in order to avoid phone number spoofing. 5. Conclusion, future work This document presented the need for requesting private information directly from another user's IP device. An initial solution based on multicast name resolution was discussed. Although this document was focused on phone numbers and SIP URIs, other private information e.g. e-mail address, DNS names, IP addresses may also be requested. Mutaf Expires July, 2007 [Page 3] Internet-Draft PIQ problem statement January 2007 References [SIPPRI] J. Peterson, "A Privacy Mechanism for the Session Initiation Protocol (SIP)", RFC 3323, November 2002. [MNR] http://en.wikipedia.org/wiki/Zeroconf Author's Address Pars Mutaf Institut National des Telecommunications Email: pars.mutaf@int-evry.fr This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Mutaf Expires July, 2007 [Page 4]