Ubiety.Stringprep.Core

An implementation of stringprep — the preparation of internationalized strings of RFC 3454 — for .NET. It ships the RFC's character tables and lets you assemble them into the profile you need.

var saslprep = PreparationProcess.Build()
    .WithMappingStep(MappingTable.Build(Mapping.B1)
        .WithValueRangeTable(Prohibited.C12, ' ')
        .Compile())
    .WithNormalizationStep(NormalizationForm.FormKC)
    .WithProhibitedValueStep(ValueRangeTable.Build(
            Prohibited.C12, Prohibited.C21, Prohibited.C22, Prohibited.C3, Prohibited.C4,
            Prohibited.C5, Prohibited.C6, Prohibited.C7, Prohibited.C8, Prohibited.C9)
        .Compile())
    .WithBidirectionalStep()
    .Compile();

saslprep.Run("I­X");   // "IX"  - the soft hyphen is mapped to nothing
saslprep.Run("Ⅸ");     // "IX"  - roman numeral nine, normalized
saslprep.Run("");     // throws ProhibitedValueException

• Getting started — install, build a profile, run it
• Building a profile — the four steps, custom tables, worked profiles
• Table reference — every RFC 3454 table and the name it has here
• API reference — generated from the source

Stringprep is not a protocol. RFC 3454 defines the machinery — a mapping step, a normalization step, a prohibition step and a bidirectional check — and leaves it to other specifications to say which tables go in which step. Those specifications are profiles: SASLprep (RFC 4013) for usernames and passwords, Nameprep (RFC 3491) for domain labels, and others. This library gives you the tables and the steps; you compose the profile.