International Domain Name

1
International Domain Name

• TWNIC
• Nai-Wen Hsu
• snw_at_twnic.net.tw

2
Domain name

• RFC 1035
• A label can not longer than 63 characters
• A domain name can not longer than 255 characters
• Maximum labels 127
• Only accept a-z,0-9,- as domain name
• Limited ASCII character code point, 37 LDH
  (Letter-Digit-Hyphen)

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International Domain Name

• IETF IDN WG adopt UNICODE 3.2
• Greek, Cyrillic, Armenian, Hebrew,
  Arabic,Syriac, Thaana, Devanagari,
  Bengali,Gurmukhi, Gujarati, Oriya, Tamil,
  Telugu,Kannada, Malayalam, Sinhala, Thai,
• 95,156 characters

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International Domain Name sample

• ??????.jp
• gwmöbler.com
• ????.tw
• ??????????.cn
• ?????.kr
• ????? . ???

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IETF IDN Standard

• IDNA (RFC3490)
• Internationalizing Domain Names in Applications
• NAMEPREP(RFC3491)
• A Stringprep Profile for Internationalized Domain
  Names
• PUNYCODE(RFC3492)
• A Bootstring encoding of Unicode for
  Internationalized Domain Names in Applications
• STRINGPREP(RFC3454)
• Preparation of Internationalized Strings

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IDNA components and interfaces
User
Input and display local interface methods (pen,
keyboard, ...)
IDNA
IDNA-aware Application (ToASCII and
ToUnicode operations may be called here)
End system
Call to resolver ACE
Application-specific Protocol ACE Unless the
protocol Is updated to handle Other encodings
xn--de-jg4avhby1noc0d
Resolver
DNS Protocol ACE
"Application" is where the application splits a
host name into labels, sets the appropriate
flags, and performs the ToASCII and ToUnicode
operations.
DNS Servers
Application Servers
7
IDNA Structure
Nameprep A Stringprep Profile for
Internationalized Domain Names
User input
(UNICODE)

IDNA

• NAMEPREP
• Mapping
• Normalization
• Prohibit

STRINGPREP
ToASCII
ToUnicode
ACE(PUNYCODE)
To resolver
ACE
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NAMEPREP

• A Stringprep Profile for Internationalized Domain
  Names
• Mapping
• Stringprep table B.1,B.2
• Normalization
• Form KC
• Prohibited Output
• Stringprep table C.1.2,2.2,3,4,5,6,7,8,9

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NAMEPREP -- Mapping

• Commonly mapped to nothing 27
• Ex
• Mapping for case-folding used with NFKC 1371
• ExA ? a (U0041?U0061) ?
  (U03AB?U03CB) ? (U3371?U0068 U0070
  U0061)

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NAMEPREP -- Normalization

• Unicode normalization with form KC

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NAMEPREP -- Normalization

• u? ?? ü
• a??a

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NAMEPREP Prohibited output

• Non-ASCII space characters 17
• Ex (NO-BREAK SPACE)
• Non-ASCII control characters 54
• Ex (DEVICE CONTROL STRING)
• Private use 133371
• Non-character code points 49
• Surrogate codes 2048

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NAMEPREP Prohibited output

• Inappropriate for plain text 4
• Inappropriate for canonical representation 12
• Change display properties or are deprecated 13
• Tagging characters 97

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PUNYCODE

• A Bootstring encoding of Unicode for IDNA
• One of the ACE(ASCII Compatible Encoding)
• Translate non-ASCII characters to ASCII
  characters
• Prefix xn--
• Ex????.tw ? xn--ciun9hb52c2za.tw

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Insufficient in IDN standard

• Current IDN standard (IDNA, NAMEPREP, PUNYCODE)
  can not solve Chinese domain name requirement
• Tradition/Simplify Chinese mapping
• Ex ? ?? ?
• Writing variant mapping
• Ex ? ?? ?

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(No Transcript)
17
Insufficient in IDN standard

• They are the same meaning but it is different
  character in different countries
• In China
• ?(529D)
• In Japan
• ?(52E7)
• In Taiwan
• ?(52F8)

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IDN administration guide line

• Registration policy to solve those problems
  listed above
• Every language has a variant table with 3 fields
• valid code point
• recommended variant
• character variant

19
Variant Table sample
Valid code point (VCP) Recommended variants by .tw (twRV) Recommended variants by .cn (cnRV) Character Variant(s) (CV) Remarks
?(4E01) ?(4E01) ?(4E01) ?(4E01) Singular-relation character(1)
?(4E04) ?(4E0A) ?(4E0A) ?(4E04) ?(4E0A) Pair-relation characters (2.1)
?(4E0A) ?(4E0A) ?(4E0A) ?(4E04) ?(4E0A) Pair-relation characters (2.1)
?(4E07) ?(4E07) ?(4E07) ?(4E07) ?(842C) Pair-relation characters (2.2)
?(842C) ?(842C) ?(4E07) ?(4E07) ?(842C) Pair-relation characters (2.2)
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Variant Table sample
Valid code point (VCP) Recommended variants by .tw (twRV) Recommended variants by .cn (cnRV) Character Variant(s) (CV) remarks
?(53F6) ?(8449) ?(53F6) ?(53F6) ?(8449) Pair-relation characters (2.3)
?(8449) ?(8449) ?(53F6) ?(53F6) ?(8449) Pair-relation characters (2.3)
?(4E2A) ?(500B) ?(4E2A) ?(4E2A)?(500B)?(7B87) Multiple-relation Characters
?(500B) ?(500B) ?(4E2A) ?(4E2A)?(500B)?(7B87) Multiple-relation Characters
?(7B87) ?(500B) ?(4E2A) ?(4E2A)?(500B)?(7B87) Multiple-relation Characters
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Variant Table

• Singular-relation character (VCPtwRVcnRVCV)
  13888(66.4)
• VCPtwRV?cnRV 2783 (13.3)
• VCPcnRV?twRV 2453(11.7)
• VCP?(twRVcnRV) 333(1.6)
• VCP?twRV?SCR 387(1.9)

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Variant Table
Number of character variant(s) 1 2 3 4 5 6 7 8
Number of Characters 13888 66.4 5156 24.7 1158 5.5 424 2.0 165 0.79 60 0.29 35 0.17 16 0.08
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Variant Table

• The table draft is prepared by the CCMT Task
  force
• organized by TWNIC from January, 2002.
• Task force members have 9 experts from
• language linguist, computer experts and DNS
  experts.
• The table draft has submitted to the Bureau of
  Standards,
• Ministry of Economic Affairs to final review.

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Registration procedure

• A Registrant should select the language(s)
• Activation of the requested domain name(s)
  Reservation of the equivalence(s) should be
  provided by the Registry, within the
  language-based character set
• The registrant can require the activation of the
  reserved equivalent domain name(s) at any time

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Registration sample

• A user select zh-tw and zh-cn language with
  domain name ???.com
• ???.com (Recommended variants for zh-tw)
• ???.com (Recommended variants for zh-cn)
• ???.com (Character Variant)
• ???.com (Character Variant)

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Q A