International characters are becoming a growing pain for Internet protocol design.
Many protocols just deal with 7-bit ASCII on the basic protocol level while there is an increasing demand for information expression in local languages at the application layer. Various protocols like Internet mail and DNS has addressed this issue by defining conventions to carry international characters over 7-bit ASCII. The problem is rather straightforward as long as the task is limited to presentation of data in a local language context, but grows to a very hard problem when the task is expanded to comparison of canonicalized strings from different sources. The problem is even harder if consistency between visual matching and matching of encoded character strings is required.

The technical plenary at the 76th IETF in Hiroshima (November 8-13 2009) recently focused in on this particular problem. Read More...

I’m currently writing a new standard for TLS which will allow the client to cache big portions of static data exchanged during TLS handshake negotiations and allow the server to omit resending this data on consecutive handshakes, such as in consecutive re-negotiations.

My slides for the TLS meeting today at the Hiroshima IETF, showing the basic approach. is available here: Cached Info (PDF).


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A new embarrassing attack was recently discovered and exploited on Server Certificates and their validation in many current browser environments.

The discovery is that current deployment of domain name matching between the domain expressed in the certificate and the domain protected by the certificate use string matching which treat character 00 (\0) as end of string.
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The TLS workgroup in the IETF (Internet Engineering Task Force) is currently heavily engaged in finding a quick solution to the just recently discovered and published attack against TLS using TLS renegotiaion. Read More...