[arabic-vip] ZWNJ Possible Risks/Issues

[Raed Al-Fayez]

Dear All,

The goal of this emails is just to share with you some of the possible risks/issues when using ZWNJ in domain names (as what many members have requested):


1-      In Unicode the ZWNJ is considered to be an invisible join control character and listed in the "Unicode Security Considerations" document which means that there are a some kind of risk when using it.

2-      Arab users (and any user who do not know ZWNJ) will not be able to type the domain name (because they will think it is a space not ZWNJ) which will lead reachability problems.

3-      Urdu/Farsi users (and other users that know ZWNJ) may not be able to type the domain name when they use Arabic keyboards (e.g. airport/internet cafes outside their countries) which will lead reachability problems.

4-      I think the current IDNA RFCs does not totally solve the issue of ZWNJ and the TAH family (0637, 0638 or 069F) you can still generate two different A-labels sharing the same U-Label (look alike)! see these links:

http://unicode.org/cldr/utility/idna.jsp?a=%D8%B7%D8%A8%D9%84%0D%0A%D8%B7%E2%80%8C%D8%A8%D9%84

http://demo.icu-project.org/icu-bin/idnbrowser?t=%D8%B7%E2%80%8C%D8%A8%D9%84



[cid:image001.jpg at 01CC7C42.C288E920]

5-      Still there are other issues not only with the TAH family (0637, 0638 or 069F) but with other code points (for example 06BE & 06FF and there might be more that share the same problem).

[cid:image003.jpg at 01CC7C42.C288E920]

[cid:image007.jpg at 01CC7C42.C288E920]



6-      When Unicode changes there might be a risk that newly added code point might have the same issues as the TAH group.

7-      ..etc

At the end I am not saying that ZWNJ is not important because we don't use it. I am fully aware that there are many languages use ZWNJ but the use in domain names might raise some risks/issues similar to what I have shown in this email.

With best regards,

Raed I. Al-Fayez
------------------------------------------
Senior IT Projects Specialist, M.Sc, PMP
Saudi Network Information Center (SaudiNIC)
Communication and Information Technology Commission (CITC)
Tel: + 966-1-2639235   - Fax: + 966-1-2639393
http://www.nic.net.sa<http://www.nic.net.sa/>

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