Masahisa Kawashima

Cryptographic alias e-mail addresses for privacy enforcement in business outsourcing

This paper proposes a method of anonymizing e-mail addresses for privacy enforcement in business outsourcing. By means of a cryptographic encoding scheme, the method generates an alias address containing a tracking ID for traceability and revocation. This feature helps an enterprise identify leakage path and revoke a cluster of leaked alias addresses in case of an address leakage incident.

An authentication method for interaction between personal servers based on the exchange of addresses

The sharing of information held on personal servers is becoming widespread, as represented by Weblogs, SNS, etc. In this situation, it is necessary for each personal server to authenticate users autonomously without any special conditions for the site to which they belong. In this paper, we propose an authentication method for interaction between personal servers. The proposal introduces a new method, which involves retrieving a public key based on the prior exchange of addresses. It requires no trusted-third-party, suppresses the number of secret data items to be managed, and enables key revocation with certainty. We investigate a possible security pitfall of the proposal which results in a risk of impersonation using DNS spoofing, and propose a countermeasure for this, showing that the risk is avoidable.

Adopting IPsec to SIP Network for On-Demand VPN Establishment between Home Networks

We have developed a new on-demand VPN system that works over a managed SIP network such as the next-generation network (NGN). The system achieves a stable broadband VPN connection between two home networks in an easy-to-use manner by using SIP for session management. The system uses telephone numbers, QoS management, and packet-filtering capabilities that are provided by the NGN. In this paper, we describe the system and focus on how IKEv2 and IPsec, with a slight extension to the port-number handling, can be adapted to an NGN that has NAT- or 5-tuple-based packet filtering within the network.