The use of non-ASCII strings in Internet protocols requires additional processing to be handled properly. As part of the Internationalized Domain Names (idn) work in 2003, a method for preparation and comparison of internationalized strings was defined and generalized to be re-used by other protocols. This "stringprep" method [RFC 3454] defines the overall framework whereas specific protocols define their own profiles. Known existing IETF profiles are:
- The Nameprep profile [RFC 3490] for use in Internationalized Domain Names in Applications (IDNA) - The iSCSI profile [RFC 3722] for use in Internet Small Computer Systems Interface (iSCSI) Names - The Nodeprep and Resourceprep profiles [RFC 3920] for use in the Extensible Messaging and Presence Protocol (XMPP) - The Policy MIB profile [RFC 4011] for use in the Simple Network Management Protocol (SNMP) - The SASLprep profile [RFC 4013] for use in the Simple Authentication and Security Layer (SASL) - The trace profile [RFC 4505] for use with the SASL ANONYMOUS mechanism - The LDAP profile (RFC 4518] for use with LDAP
The IAB completed a review of IDN and made recommendations for change [RFC 4690], which triggered a new version of the IDNA protocol called IDNA2008. Whereas IDNA2003 was tied to Unicode 3.2 via stringprep, IDNA2008 does not use the stringprep method, but instead uses an algorithm based on the properties of Unicode characters, which makes it agile to the Unicode database version. The protocols using stringprep need Unicode version agility and therefore need to investigate whether and how to move away from the current stringprep approach, with the associated challenges of backward compatibility and migration.
The goal of this group is to assess whether a new method based on the new IDNA2008 algorithmic approach is the appropriate path forward for existing stringprep protocols as well as for other application protocols requiring internationalized strings.
The group will evaluate if a new generalized framework based on the algorithmic approach is appropriate and, if so, define it.
The group will analyze existing stringprep profiles and will do one of the following with regard to each profile:
1. Develop a replacement for the profile in close collaboration with the related protocol working group (if any).
2. Collaborate with another active working group which will be developing the new profile as part of its charter.
3. Advise the authors of profiles for which there is no active working group how to proceed.
The group will also define a set of best current practices for preparation and comparison of internationalized strings.
Because the framework, profile replacements, and guidelines are very much interrelated, work on them will proceed in parallel as much as possible.
Based on normal working group processes for achieving consensus, the group will attempt to gather input from, and may provide advice to, "customers" working on IETF technologies other than those listed above, including but not limited to Network Address Identifiers (RFC 4282) and Kerberos (RFC 4120). However, the group will prioritize work on the listed stringprep profiles higher than work on other technologies, and will formally accept additional tasks as official milestones only after rechartering.
In completing its tasks, the working group should collaborate with other teams involved in internationalized identifiers, such as the IETF's IRI and EAI working groups as well as other relevant standards development organizations (e.g., the Unicode Consortium).
1. Problem statement / analysis of existing stringprep profiles (Informational).
2. Possible new framework to replace stringprep (Standards Track).
3. Possible replacements for the existing IETF stringprep profiles as listed earlier in this charter (Standards Track).
4. String preparation and comparison guidelines (BCP).