The Internationalized Resource Identifier (IRI) is an internet protocol standard which builds on the

Uniform Resource Identifier A Uniform Resource Identifier (URI), formerly Universal Resource Identifier, is a unique sequence of characters that identifies an abstract or physical resource, such as resources on a webpage, mail address, phone number, books, real-world obje ...

(URI) protocol by greatly expanding the set of permitted characters. It was defined by the

Internet Engineering Task Force The Internet Engineering Task Force (IETF) is a standards organization for the Internet standard, Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster ...

(IETF) in 2005 in RFC 3987. While URIs are limited to a subset of the

US-ASCII ASCII ( ), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of 95 (English language focused) printable character, printable and 33 control character, control c ...

character set (characters outside that set must be mapped to octets according to some unspecified character encoding, then percent-encoded), IRIs may additionally contain most characters from the

Universal Character Set The Universal Coded Character Set (UCS, Unicode) is a standard set of characters defined by the international standard ISO/ IEC 10646, ''Information technology — Universal Coded Character Set (UCS)'' (plus amendments to that standard), w ...

(Unicode/

ISO 10646 The International Organization for Standardization (ISO ; ; ) is an independent, non-governmental, international standard development organization composed of representatives from the national standards organizations of member countries. Mem ...

), including Chinese, Japanese, Korean, and

Cyrillic The Cyrillic script ( ) is a writing system used for various languages across Eurasia. It is the designated national script in various Slavic, Turkic, Mongolic, Uralic, Caucasian and Iranic-speaking countries in Southeastern Europe, Ea ...

characters.

Syntax

IRIs extend URIs by using the

, where URIs were limited to

ASCII ASCII ( ), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of 95 (English language focused) printable character, printable and 33 control character, control c ...

, with far fewer characters. IRIs may be represented by a sequence of octets but by definition are defined as a sequence of characters, because IRIs may be spoken or written by hand.

Compatibility

IRIs are mapped to URIs to retain backwards-compatibility with systems that do not support the new format. For applications and protocols that do not allow direct consumption of IRIs, the IRI should first be converted to Unicode using canonical composition normalization (NFC), if not already in Unicode format. All non-ASCII code points in the IRI should next be encoded as

UTF-8 UTF-8 is a character encoding standard used for electronic communication. Defined by the Unicode Standard, the name is derived from ''Unicode Transformation Format 8-bit''. Almost every webpage is transmitted as UTF-8. UTF-8 supports all 1,112,0 ...

, and the resulting bytes percent-encoded, to produce a valid URI. Example: The IRI https://en.wiktionary.org/wiki/Ῥόδος becomes the URI https://en.wiktionary.org/wiki/%E1%BF%AC%CF%8C%CE%B4%CE%BF%CF%82 ASCII code points that are invalid URI characters ''may'' be encoded the same way, depending on implementation. This conversion is easily reversible; by definition, converting an IRI to an URI and back again will yield an IRI that is semantically equivalent to the original IRI, even though it may differ in exact representation. Some protocols may impose further transformations; e.g.

Punycode Punycode is a representation of Unicode with the limited ASCII character subset used for Internet hostnames. Using Punycode, host names containing Unicode characters are transcoded to a subset of ASCII consisting of letters, digits, and hyphens, w ...

for DNS labels.

Advantages

There are reasons to see URIs displayed in different languages; mostly, it makes it easier for users who are unfamiliar with the Latin (A–Z) alphabet. Assuming that it isn't too difficult for anyone to replicate arbitrary Unicode on their keyboards, this can make the URI system more accessible.

Disadvantages

Mixing IRIs and

URIs can make it much easier to execute

phishing Phishing is a form of social engineering and a scam where attackers deceive people into revealing sensitive information or installing malware such as viruses, worms, adware, or ransomware. Phishing attacks have become increasingly sophisticate ...

attacks that trick someone into believing they are on a different site than they really are. For example, one can replace an ASCII "a" in www.myfictionalbank.com with the Unicode look-alike " α" to give www.myfictionαlbank.com and point that IRI to a malicious site. This is known as an

IDN homograph attack The internationalized domain name (IDN) homograph attack (sometimes written as homoglyph attack) is a method used by malicious parties to deceive computer users about what remote system they are communicating with, by exploiting the fact that man ...

. While a URI does not provide people with a way to specify web resources using their own alphabets, an IRI does not make clear how web resources can be accessed with keyboards that are not capable of generating the requisite internationalized characters. This means that IRIs are now handled in a way very similar to many other software which might require the use of a non-keyboard

input method An input method (or input method editor, commonly abbreviated IME) is an operating system component or program that enables users to generate characters not natively available on their input devices by using sequences of characters (or mouse oper ...

when dealing with texts in various languages.

References

External links