Drummond Group, LLC This document provides an applicability statement (RFC 2026, Section 3.2) describing how to securely exchange structured business data over HTTP. Structured business data may be XML; Electronic Data Interchange (EDI) in either the American National Standards Committee (ANSI) X12 format or the UN Electronic Data Interchange for Administration, Commerce, and Transport (UN/EDIFACT) format; or other structured data formats. The data is packaged using standard MIME structures. Authentication and data confidentiality are obtained by using Cryptographic Message Syntax with S/MIME security body parts (see Section 10.1). Authenticated acknowledgements make use of multipart/signed Message Disposition Notification (MDN) responses to the original HTTP message. This applicability statement is informally referred to as "AS2" because it is the second applicability statement, produced after "AS1" (RFC 3335). This document obsoletes RFC 4130 and stands on its own without reference to AS1 or SMTP, except where required for IANA registry updates. This document also updates IANA registries originally created by RFC 3335 and RFC 4130.