EDIINT Working Group Dale Moberg Internet draft Dick Brooks Expires: October 2001 Rik Drummond April 1, 2001 HTTP Transport for Secure EDI draft-ietf-ediint-as2-08.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. To view the current status of any Internet-Draft, please check the ``1id-abstracts.txt'' listing contained in an Internet- Drafts Shadow Directory, see http://www.ietf.org/shadow.html. Any questions, comments, and reports of defects or ambiguities in this specification may be sent to the mailing list for the EDIINT working group of the IETF, using the address . Requests to subscribe to the mailing list should be addressed to . Abstract This document describes how to exchange structured business data securely using HTTP transport for EDIFACT, X12, XML or other used for business to business data interchange. The data is packaged using standard MIME content-types. Authentication and privacy are obtained by using CMS (S/MIME) or OpenPGP security body parts. Authenticated acknowledgements make use of multipart/signed replies to the HTTP POST requests. This document extends the procedures and payload packaging options of AS1 in the following ways: HTTPS may be used to obtain data privacy, both synchronous and asynchronous reply procedures are described, multipart/form-data packaging may be used, a generalized multipart/report format is added to the MDN format of AS1, replies may include a multipart/mixed payload that contains both the acknowledgement and an additional EDI payload. This document is intended to be read in conjunction with AS1 and the referenced RFCs defining the MIME and cryptographic packaging that are used to obtain secure, authenticated, and acknowledged transport. Moberg, Brooks, Drummond [page 1] HTTP Transport for Secure EDI April 1, 2001 Feedback Instructions: If you want to provide feedback on this draft, follow these guidelines: -Send feedback via e-mail to the ietf-ediint list for discussion, with "AS#2" in the Subject field. To enter/follow the discussion, you need to subscribe at ietf-ediint@imc.org. -Be specific as to what section you are referring to, preferably quoting the portion that needs modification, after which you state your comments. -If you are recommending some text to be replaced with your suggested text, again, quote the section to be replaced, and be clear on the section in question. Table of Contents 1. Introduction 1.1 Purpose and relation to previous work 1.2 Overall operation 2. Stages and Details of HTTP EDI Transmission and Acknowledgment 2.1 Requesting receipts in the POSTED request 2.1.1 Requesting MDN-based receipts 2.1.2 Requesting Generalized receipts 2.1.3 Summary Remarks on Receipt request options 2.2 Additional Commonly Used Headers 2.3 Sending EDI in HTTP POST Requests 2.4 Using Transport Layer Security for Transmission 2.5 Response Status Codes in Replies 2.6 Receipt Reply 2.6.1 MDN Receipts and Signed MDN Receipts 2.6.2 Generalized Receipts and Signed Generalized Receipts 2.7 Additional Reply Content 2.8 Non-Repudiation of the POST Reply 2.9 Error Recovery 3. Other differences between HTTP and SMTP based transport 3.1 Unused MIME headers and operations 3.1.1 Content-Transfer-Encoding not used 3.1.2 Epilogue must be empty 3.1.3 Lengthy message bodies and Message/partial 3.2 Differences in MIME or other headers or parameters used 3.2.1 Content-Length needed 3.2.2 Final Recipient and Original Recipient 3.2.3 Message-Id and Original-Message-Id 3.2.3 Host header 3.3 New Options for HTTP transport A. AS 2 MIME templates. B. Using AS2 Extensions in the GISB Protocol C. Samples of AS 2 Protocol Data Units D. Acknowledgments E. References F. Security Considerations G. Authors' Addresses Moberg, Brooks, Drummond [page 2] HTTP Transport for Secure EDI April 1, 2001 1. Introduction 1.1 Purpose and relation to previous work Early work on Internet EDI focused on specifying MIME content types for EDI data [MIMEEDI] The functional requirements document , "Requirements for Interoperable Internet EDI," [EDIINT] provides extensive information on EDI security and the business and user processes that can benefit from the use of EDI security. In addition, MIME structures appropriate for SMTP transport of the packaged EDI data are specified in ([AS1] "MIME-based Secure EDI" ) as well as the details needed to support signed receipts as acknowledgments. The framework of [AS1] shows how to implement the security features-- specifically data privacy, data integrity/authenticity, non-repudiation of origin and non-repudiation of receipt -- found to be requirements for secure EDI. In this document, it is assumed that the reader is familiar with the SMTP/MIME transport document, the requirements document, and the RFCs applied or referenced in those documents. This draft, like the SMTP/MIME transport document, builds on previous RFCs and is attempting to "re-invent" as little as possible. The goal here is to specify how previously specified MIME messaging structures and operations can be adapted for use with HTTP servers and clients to obtain secure, reliable, and acknowledged transport for EDI and other business data. The applicability statement, [AS1] "MIME-based Secure EDI," explained the basic EDI transaction using the concept of a "secure transmission loop" for EDI. This loop involves one organization sending a signed and encrypted EDI interchange to another organization, requesting a signed receipt, followed by the receiving organization sending this signed receipt back to the sending organization. The transmission, therefore, involves the following stages: 1. The organization sending business data encrypts the data and provides a digital signature, using either PGP/MIME or S/MIME. In addition, they request a signed receipt. 2. The receiving organization decrypts the message and verifies the signature, resulting in verified integrity of the data and authenticity of the sender. 3. The receiving organization then sends a signed receipt using a signature over the hash of a message disposition notification, which contains a hash of the received message. The above stages describe the functionality that would satisfy all security requirements. Applications are expected to be able to provide full functionality, though users may agree to exchange data using only a restricted subset of Moberg, Brooks, Drummond [page 3] HTTP Transport for Secure EDI April 1, 2001 functionality. For example, businesses may agree to send signed data using TLS, and only request a simple, unsigned receipt. Implementations are expected to be configurable so that they may support business community agreements that use subsets of the full functionality. In this document, the goal is to make use of HTTP instead of SMTP as a transport protocol, and make the changes that are needed to adapt to protocol packaging differences. In either transport case, the body of the message is a MIME structure, using MIME headers ("content-type" and other "content-X" tags) to convey information about the data being transported. Also, one primary use of SMTP RFC 822 headers within SMTP based transport of secure EDI has been to enable requests for acknowledgements and to specify options for signatures over acknowledgements (asymmetric encryption and cryptographic hash algorithm preferences). One way to convey this information within the HTTP transport context is to use either HTTP entity-headers or extension-headers [11, section 7.1] that have the syntax of SMTP headers. Only the "From" header is overloaded by possibly different usages in the SMTP and HTTP contexts. The "From" header normally contains machine-usable email addresses as defined in [SMTPMSG]. The usage of the "From" header in [HTTP] section14.22 is to provide the email address of an administrative contact for the HTTP client. The function of the "From" header in the SMTP context of secure EDI transport has been to supply a value used in constructing the MDN style receipt. But the MDN receipt has been found to be too restrictive for some commercial EDI transport scenarios [GISB]. So alternative receipt mechanisms will be provided that, among other things, will remove any conflicts arising from trying to reuse the SMTP-MDN roles of "From" within the context of HTTP reserved usage of "FROM". Also, it is currently difficult to make use of HTML [HTML] and simple scripting to send HTTP entity-headers as part of the HTML FORM tag construct. For HTML-based POST situations [GISB], it is useful to specify ways to convey 'metadata' needed for the secure transmission loop that do not make use of HTTP headers. One way to specify this data is by using the MIME multipart/form-data packaging specified in [FORMDATA]. For SMTP transport, the receipt and signed receipt functions are implemented using Message Disposition Notifications [MDN] and Multipart/signed Message Disposition Notifications [AS1]. For HTTP transport, generalization of the Message Disposition Notification is useful. The MDN is a special kind of multipart/report [REPORT]. For MDNS, specialization is achieved by assigning the "report-type" parameter in the content-type header the special value, "disposition-notification" and by having the second body part Moberg, Brooks, Drummond [page 4] HTTP Transport for Secure EDI April 1, 2001 (the "machine-readable" body part) have the MIME content-type, "message/disposition-notification". To generalize a MDN, all that is needed is to remove the restrictions that make the underlying multipart/report into a MDN. In other words, the "report-type" parameter [REPORT, section 1] is given a new value and the second body part is changed to a content-type other than "message/disposition-notification". Acknowledgements defined by these changes will be referred to as "generalized receipts. Each receipt of this kind will have its own specific report-type parameter and its own specifications for the syntax and semantics of the automated response body part. Implementations are encouraged to be able to register new report-type handlers using only configuration changes (not recompiling) that specify how to process new report-type values. Nothing else needs to be changed to construct reply acknowledgements that are not restricted by the semantics of MDNs. Specifically, a signed reply will still be constructed by using a multipart/signed package to wrap up generalized receipts with their signatures. Finally, within the HTTP transport context, it is useful to make use of Transport Layer Security [TLS] to provide privacy. Compression can be provided using HTTP content-codings [HTTP], sections 3.5, 14.3, 14.12]. (Content codings are not be be confused with the MIME concept of content transfer encodings.) A variety of other minor differences (for example, absence of content-transfer-encoding) are noted below and summarized in the concluding section. 1.2 Overall operation A HTTP POST operation [HTTP] is used to send appropriately packaged EDI, XML, or other business data. The Request-URI ([HTTP], section 9.5) identifies a process to unpack and handle the message data and to generate a reply for the client that contains a message disposition acknowledgement or a multipart/report, signed or unsigned, and possibly other turnaround transactions. This request/reply transactional interchange provides secure, reliable, and authenticated transport for EDI or other business data using HTTP; the security protocols and structures used also support auditable records of these transmissions, acknowledgements, and authentication. 2. Stages and Details of HTTP EDI Transmission and Acknowledgment A data file or stream is first structured into one of the message templates described in [AS1], sections 4.2.1 to 4.2.4 or 4.3.1 to 4.3.4 for PGP/MIME or S/MIME security. In addition to the content-types of [MIMEEDI], applications should be prepared for handling other content-types used in business to business transactions, such as those for XML [MIME-TYPES]. For convenience, these message templates, adapted for the HTTP transport context, are provided in Appendix A below. Moberg, Brooks, Drummond [page 5] HTTP Transport for Secure EDI April 1, 2001 If TLS is to be used, the typical packaging will be that described in sections 4.2.2 or 4.3.2; that is, a multipart/signed message will be created with no encryption in the message. Otherwise, if privacy is desired, message templates 4.2.4 or 4.3.4 are used. Content transfer encoding is not used and a content-length field is to be provided. If HTML-based POST is used (using the METHOD=POST attribute within the "FORM" tag) [HTML, 17 Forms], then the message payload will be packaged in the input-data element of a multipart/form-data. The metadata needed for application layer routing, identification, requesting a reply and other transaction operations can be packaged in message body parts in the multipart/form-data. The labels for the metadata values are found in the "name" parameter of the Content-Disposition header in each form-data part as discussed in [FORMDATA, section 3]. In general, both HTTP servers and HTTP clients handling the message templates of [AS1] should be prepared to process these basic EDIINT data formats when they are embedded within MIME multiparts. In addition to the enveloping and MIME media type options defined in sections 4.2.x and 4.3.x of "MIME-based Secure EDI" [AS1], this specification enables the transport of payload objects containing other MIME media types. Implementors are to follow the appropriate specifications identified under "References" in [MIME-TYPES], for the type of object being transmitted. For example, to send an XML object, the MIME media type of application/xml is used in the Content-type MIME header and the specifications for enveloping the object are contained in [XMLTYPES]; for example: Content-type: application/xml; charset="utf-8" Many of the specifications referenced by [MIME-TYPES] were designed for SMTP transports. Implementors are advised to make appropriate adjustments for HTTP transport as indicated in section 4 of this document. Finally, several industry groups currently make use of "encapsulated"(or opaque) signatures within encrypted or signed objects. Encapsulated signatures should be supported in order to accommodate these existing practices. Objects containing encapsulated signatures must be prepared according to the specifications contained in section 3.4.2 of [SMIMEV2] or, in the case of PGP, according to the specifications contained in section 6.2 of "MIME Security with Pretty Good Privacy (PGP)" [MIMEPGP] and "OpenPGP Message Format" [RFC2440]. 2.1 Requesting Receipts 2.1.1 Requesting MDN-based receipts For requesting MDN based receipts, the originator supplies metadata using the syntax of extension headers (the [SMTPMSG] header syntax) that precede the message body. Moberg, Brooks, Drummond [page 6] HTTP Transport for Secure EDI April 1, 2001 The header "tags" are as follows: A Disposition-Notification-To header is added to indicate that a message disposition notification is requested in the reply to the POST request. This header is specified in [MDN]. It may have values other than email addresses, such as a D-U-N-S number, when it is found as a name parameter in a form-data body part When this tag is used in HTTP extension headers, it follows the MDN usage. A Message-ID header is added to support message reconciliation, so that an Original-Message-Id value can be returned in the MDN body part of the receipt. (The term "Receipts" is here used to refer to the signed or unsigned multipart/report content.) Both "From" and "To" extension headers are to be supplied. The "From" value needs to have an email address as specified in [SMTPMSG] and [HTTP]. If other uses of "From" are needed, the generalized receipts to be next discussed should be used. There the role of "From" is replaced by symbols not having a reserved HTTP or SMTP usage. Other headers, especially "Subject" and "Date", should be supplied; the values of these headers are often mentioned in the human-readable section of a MDN to aid in identifying the original message. A Disposition-Notification-Options header is used to request a signed message disposition notification. The parameters used to select protocols for signed message disposition notification are found in [AS1]. Disposition-Notification-To is a name that, if present, indicates that the MDN style of receipt is to be used. Disposition-notification-options identifies characteristics of message disposition notification in accordance with [AS1] and [MDN]. A Receipt-delivery-option is a header whose value is a URL that indicates how the receipt is to be delivered. This header is only used within AS2. The default mode of operation is synchronous within HTTP transport, which means that the receipt (be it MDN, signed MDN, generalized report receipt, or signed report receipt) is returned in the reply body. By using the "receipt-delivery-option," an asynchronous reply mode can be requested. The values for this option are URLs that indicate the destination for the reply, and may use any appropriate protocol ("mailto", "http", and "https" will be the more common types) for this information. If this header/metadata is absent, then the mode of operation is synchronous, which means that the receipt is returned in the reply to the current HTTP request. 2.1.2 Requesting Generalized Receipts In this section, the ways to request generalized receipts are specified. Generalized receipts are multipart/reports Moberg, Brooks, Drummond [page 7] HTTP Transport for Secure EDI April 1, 2001 with a report-type other than "disposition-notification," and a second automated response with a content type other than "message/disposition-notification". For requesting generalized receipts using the MIME template for multipart/reports [REPORTS], the following metadata elements will be useful. A specific example of a generalized receipt with report-type "GISB-Acknowledgement-Receipt" will be presented in appendix B. When the term "metadata" is used in the following, the term indicates that the information may be supplied in one of two ways: First, the metadata information may be supplied using the syntax of HTTP headers. That is, the symbol name is followed by a colon and its value follows; the header is subject to processing of structured field bodies [SMTPMSG, section 3.1.4], also including parameters. Second, the metadata information may be supplied by using the syntax of the "name" parameter within the "Content-Disposition" header of the multipart/form-data structure, when that MIME packaging [FORMDATA] is used. For example, --boundaryformdata Content-Disposition: form-data; name="Receipt-Report-Type" GISB-Acknowledgement-Receipt --boundaryformdata Within HTML, the symbols used for these names correspond to the value of the name attribute within the INPUT element, where the "type" attribute has a "text" value. [HTML], section 18; for example,
To indicate the various options for generalized receipts, the basic metadata that the POSTing client needs to convey to the replying server are: "Receipt-Disposition-To", "Receipt-report-type", "Receipt-Security-Selection", and "Receipt-Delivery-Option". The presence of the metadata value "Receipt-Disposition-To", using the extension header syntax, indicates a request for a generalized receipt. Because HTTP already has a role for the "From" header, the "Receipt-Disposition-To" header is used to avoid conflicts with [HTTP], when using the header syntax for metadata. (Within a multipart/form-data package, the "From" value can be used to identify the sending party without any Moberg, Brooks, Drummond [page 8] HTTP Transport for Secure EDI April 1, 2001 conflict with HTTP headers.) Notice that the value for this identifier need not be an email address or a URL. In this way, other systems of identification (such as a DUNS number) may be used, if needed. Notice that the information needed for delivery of the receipt is found in the receipt-delivery-option element described below; delivery information is not generally needed if the default mode of operation occurs. In that case, the receipt just goes back in the reply to the current HTTP request. "Receipt-Report-Type" indicates the desired value of the "report-type" parameter in the multipart/report content type of a specific version of the generalized receipt. This parameter must be supplied when "Receipt-Disposition-To" is used to indicate a request for a generalized receipt because this indicates what specific type of receipt is desired. An example for this value (discussed in appendix A) is "GISB-Acknowledgement-Receipt". "Receipt-Security-Selection" is a name that indicates the protocol and algorithm choices for a digital signature over the receipt. Signatures are always in multipart/signed packages. The format for protocol and algorithm choices is that used in [AS1] and [MDN]; for example, Receipt-Security-Selection: signed-receipt-protocol=optional,pkcs7-signature; signed-receipt-micalg=optional,rsa-sha1 "Receipt-Delivery-Option" is used to indicate the URL for asynchronous delivery of the receipt. While the default mode of operation within HTTP transport is to return the receipt(be it MDN, signed MDN, generalized receipt, or signed generalized receipt) in the reply body, asynchronous reply is allowed through use of this symbol. The URLs will typically use the "MAILTO", "HTTP", and "HTTPS" schemes. For the HTTP and HTTPS schemes, the POST method is to be used. 2.1.3 Summary Remarks on Receipt request options Applications are encouraged to support handling all metadata values whether they make use of the name parameter syntax within a multipart/form-data or whether they use the message header syntax used in SMTP or HTTP headers [SMTPMSG]. If metadata items are repeated in extension headers and in form-data parts, but the values are not the same, the extension header values will be selected for use. Because the value in Receipt-Disposition-To may have no significance for how the receipt is transported, the extension header "Receipt-delivery-option" is to be used to provide that information. Moberg, Brooks, Drummond [page 9] HTTP Transport for Secure EDI April 1, 2001 The receipt-delivery-option's value should be a URL indicating the delivery transport destination for the receipt. The Receipt-delivery-option field is used when asynchronous delivery is desired. It should not be present if the intention is to deliver the reply synchronously; synchonous delivery of the reply is the default mode of delivery. For signed generalized receipts, an extension header of "Receipt-security-selection" should be added to indicate the desired security protocol for the multipart/signed over the multipart/report. In summary, the receipt request and construction processes now have the following options: 1. Receipt requests are made by conveying metadata values using a syntax of either the name parameter in a multipart/form-data's Content-Disposition headers or by using a syntax of HTTP extension headers. 2. Both MDN and generalized receipts can be requested using either syntax. However, using an extension header syntax and requesting a MDN receipt means restricting the "From" values to email addresses. 3. Either type of receipt comes in signed or unsigned versions. 4. Finally, receipts may be delivered synchronously (delivered in the HTTP reply) or asynchronously by using the "Receipt-delivery-option" header. 2.2 Additional Commonly Used Headers The following set of header data elements are also available for use. Organizations wishing to use this specification for the secure and reliable transport of business documents are not required to utilize all of these headers and are free to use whatever subset they deem appropriate for their business needs. TO: The To name contains an identifier identifying the intended recipient of a data exchange and may be D&B D-U-N-S number [DUNS] or other agreed upon identifier system. Applications should allow users to configure these elements in the automated HTTP agents processing these values. For example, the body part MIME header line looks like the following line: Content-Disposition: form-data; name="To" FROM: The From name contains a textual value identifying the sender of a data exchange, such as the a D&B D-U-N-S number [DUNS] as in [GISB]. Because "From" has a specified use within [HTTP], the From name parameter is not to be considered equivalent Moberg, Brooks, Drummond [page 10] HTTP Transport for Secure EDI April 1, 2001 to the extension header. If an extension header "From" is to be used it should within HTTP, it should conform to the usage, syntax, and semantics of [HTTTP] section 14.22. The extension header counterpart of the sender of a data exchange is the extension header version of "Receipt-disposition-to". INPUT-FORMAT: The Input-format name identifies the type of data contained in a data file. AGENT: The Agent name parameter indicates the network or agent where the data exchange originated. APPLICATION: The Application name identifies the application used to process the data next(after the URI-request process has finished with the stream). DATETIME: The DateTime name provides the date and time the data was created and uses the format specified in [SMTPMSG] as updated by RFC 1123. REFNUM: The RefNum is an integer value used to uniquely identify the communication exchange and is in a textual format. The RefNum is similar to the Message-ID and Content-Id headers of SMTP that are used in constructing values in receipts based on MDNs. USERPARAM: The UserParam is a user defined parameter. Version: Version is a protocol version number [GISB]. TRANSACTION-SET: Transaction-set is an optional data element identifying the EDI transaction. INPUT-DATA: Input-data is the sending side's local file system name for the file being sent. The payload is contained as the body part of this header element. PRIORITY: The "Priority" name is used to indicate the processing priority of each message relative to other messages sent by a given party. The value "1" indicates highest priority and a value of "5" indicates the lowest priority. EXPIRATION: The "Expiration" name is used to indicate the date and time at which a message is no longer transportable. No message delivery should be attempted beyond the date and time specified in this value. The date/time format must follow the specifications contained in section 5 of RFC822. Moberg, Brooks, Drummond [page 11] HTTP Transport for Secure EDI April 1, 2001 2.3 Sending EDI in HTTP Client Requests using POST For sending EDI, the following protocol elements are typically present: a request line ([HTTP], section 5.1), entity headers, a CRLF pair to mark the end of the entity headers, followed by the message-body. The request line will have the form: "POST Request-URI HTTP/1.1", with spaces and followed by a CRLF. The Request-URI is typically exchanged out of band, as part of setting up a bilateral trading partner agreement. Applications should be prepared to deal with an initial reply containing a status indicating a need for authentication of the usual types used for authorizing access to the Request-URI ([HTTP], section 10.4.2 and elsewhere). Automation of this process is not discussed in this document but might involve obtaining a session URL from a page requesting authentication and possibly other information about proposed EDI standard versions and other trading conventions to be used. The request line is followed by entity headers specifying content length ([HTTP] section 14.14) and content type [HTTP], section 14.18. The Host request header ([HTTP] sections 9 and 14.23) is also included. The entity or extension headers used for requesting a MDN (unsigned or signed) have previously been mentioned, as have those ("To" "From" "Message-Id") that are needed as values for MDN fields or for other receipt requests. For generalized receipts based on the multipart/report content type, the metadata can be the values found in extension headers, but can also be placed in body parts of a multipart/form-data using "name" parameters in the content-disposition header. Finally, the payload is found in any of the message patterns of [AS1] sections 4.2.1 to 4.2.4 or 4.3.1 to 4.3.4 for PGP/MIME or S/MIME security. These payloads may arrive as the "input-data" part of the multipart/form-data or may even be enclosed in some other multipart. 2.4 Using Transport Layer Security To use Transport Layer Security [TLS], the request-URI should indicate the appropriate scheme value, HTTPS. Usually only a multipart/signed message body would be sent using TLS, as encrypted message bodies would be redundant. Encrypted message bodies are not prohibited, however. For asynchronous receipt delivery requests, use the "Receipt-delivery-option" header with a URL value making use of the HTTPS scheme to obtain security privacy. 2.5 Response Status Codes in Replies The status line for response to errors in the POST request line will be provided by a status line with the following protocol elements present ( [HTTP], section 6.1 ) : HTTP version (normally, HTTP/1.1), a status code, reason phrase, and CRLF. Moberg, Brooks, Drummond [page 12] HTTP Transport for Secure EDI April 1, 2001 The status codes return status concerning HTTP operations. For example, the status code 401, together with the WWW-Authenticate header, is used to challenge the client to repeat the request with an Authorization header. Other explicit status codes are documented in [HTTP], sections 6.1.1 and throughout section 10. For errors in the request-URI, 400 ("Bad Request"), 404 ("Not Found") and similar codes are appropriate status codes. These codes and their semantics are specified by [HTTP]. A careful examination of these codes and their semantics should be made before implementing any retry functionality that is described below; specifically, retries should not be made if the error is not transient or if retries are explicitly discouraged (for real authentication failures, for example.) 2.6 Receipt Reply The details of the response to the POST command vary depending upon whether a receipt has been requested and upon what kind of receipt has been requested. With no extended header requesting a receipt, and no errors accessing the request-URI specified processing, the status line in the Response to the POST request should be in the 200 range. Status codes in the 200 range should also be used when an entity is returned (a signed receipt in a multipart/signed content type or an unsigned receipt in a multipart/report). Even when the disposition of the data was an error condition at the authentication, decryption or other higher level, the HTTP status code should indicate success at the HTTP level. The HTTP server-side application may respond with an unsolicited multipart/report as a message body that the HTTP client might not have solicited, but this may be discarded by the client. Applications should avoid emitting unsolicited receipt replies because bandwidth or processing limitations might have led administators to suspend asking for acknowledgements. When a Disposition-Notification-To extension header is present in the POST request entity headers, then entity headers for the MDN should be included. The content type for the MDN receipt ( multipart/report [REPORT] or multipart/signed [SECURITY]) should be included in the Response entity headers. The The basic responsibilities of responding to requests are discussed in [AS1] section 5, and in detail within section 5.2.1. 2.6.1 MDN based Receipts and Signed MDN Receipts Message Disposition Notifications, when used in the HTTP reply context, will closely parallel a SMTP MDN. For example, the disposition field is a required element in the machine readable second part of a multipart/report for a MDN. The final-recipient-field([MDN] section 3.1) value should be derived from the entity headers of the request Moberg, Brooks, Drummond [page 13] HTTP Transport for Secure EDI April 1, 2001 If the "To" field is missing, for signed messages, the value for Original-recipient may be the email address field from the signer's X.509 attribute for email addresses, if that value is available. For a MDN, an application must report the Message-ID of the request. The human readable part (the first part of the multipart/report) should include items such as the subject, date and other information when those fields are present in entity header fields following the POST request The HTTP reply should normally omit the third optional part of the multipart/report (used to return the original message or its headers in the SMTP context). 2.6.2 Generalized Receipts and Signed Receipts For generalized receipts, the multipart/report [REPORT] or a multipart/signed containing a multipart/report as the signed data is the basic MIME packaging. Each generalized receipt needs a value for the multipart/report parameter, "report-type," a selection of a content-type for its second body part, when signed, a hash value over a defined portion of the original message and, when asynchronously delivered, information allowing the identification of the original POSTed message. The basic structure of the multipart/report is used so that the first part is a "human-readable" message concerning the received message. The second part should be for automated process utilization. It should at least possess some common Internet syntax for expressing names and values, such as the [SMTPMSG] header syntax, XML, or some MIME content type correlated with automated processing. The MDN requirements, therefore, are removed for this second part, but information used in MDNs may be used here. The third part of the multipart report is usually omitted in the HTTP context, but could include the extension headers, or even the entire payload, to provide diagnostic information. A multipart/signed over a multipart/report is constructed precisely in the same way as a multipart/signed over a MDN [AS1]. One metadata element should be within the automated part. This is the Received-Content-MIC (also allowing X-Received-Content-MIC). This value is constructed and formatted as described in [AS1] and the syntax should be either RFC822: Received-Content-MIC: w7AguNJEmhF/qIjJw6LnnA==,rsa-md5 or simple XML w7AguNJEmhF/qIjJw6LnnA== Moberg, Brooks, Drummond [page 14] HTTP Transport for Secure EDI April 1, 2001 Any original metadata thought useful to include in the automated part may be reflected back using "Original-X", as in Original-Message-ID: <43141asfioufasd@somewhere.com> Otherwise the automated acknowledgement semantics are left open to further semantic specification by specific electronic commerce communities, such as in [GISB]. Each specialization of the generalized receipt should make use of a specific identifying value to be placed in the parameter "report-type," Content-Type: multipart/report; report-type="identifying-value"; boundary="=-Trfds88fd99" Implementations should attempt to be configurable to allow for new report-type values to be added; communities can then agree to the specific extensions they need to support application level routing, transaction identification, timestamps, and other specialized information about the data they have exchanged. 2.7 Additional Reply Content In general, both HTTP servers and HTTP clients should be prepared to process the basic EDIINT data formats when they are embedded within MIME multiparts. This is true for HTTP request payloads as well as HTTP reply payloads. So, as previously mentioned, for HTML-based POSTS, any of the EDIINT templates described in [AS1], sections 4.2.1 to 4.2.4 or 4.3.1 to 4.3.4 for PGP/MIME or S/MIME security, may be found as parts of a multipart/form-data. [Consult Appendix A for the templates adapted for this document.] In addition, the response to the POST operation may include other MIME wrapped content besides an MDN Receipt, Signed MDN, Generalized Receipt or Signed Generalized Receipt. If a receipt was requested within the POST data, and additional content is to be returned, the receipt multipart/report must be combined with the other data using some MIME multipart pattern. Real-time EDI processing systems may use MIME multipart content-types to include a response EDI message, for example, a Quote in response to a Request-For-Quote transaction. Also, if requested, the sender may request an asynchronous mode for return of receipt. This mode is indicated by including the metadata for Receipt-delivery-option as explained above. 2.8 Non-Repudiation of the POST Reply If the reply to a POST operation needs a MDN receipt for non- repudiation (for example, the reply includes content other than a receipt), the top-level headers in the response include the same headers required for POST data described above: Disposition-Notification-To, Message-ID, From, and To. Other headers described above used in a MDN should be included, for example, Date and Subject. Moberg, Brooks, Drummond [page 15] HTTP Transport for Secure EDI April 1, 2001 The MDN receipt of the response data is returned using a subsequent POST operation. A POST operation used only to transmit an MDN should not include the Disposition- Notification-To receipt request, and only a 200 ("OK") response would be expected. An MDN in response to a reply may be combined with a subsequent EDI message sent with a POST operation, for example a Purchase-Order transaction in response to a Quote. The MIME multipart/mixed form is used to combine the MDN with the other data, the same as for a POST reply. 2.9 Error Recovery If the HTTP client fails to read the HTTP server response data, the POST operation with identical content (including Message-ID, RefNum, and other header elements) should be repeated, if the error condition is transient. The Message-ID or RefNum on a POST operation can be reused if and only if all of the content (including the original Date) is identical. Details of the retry process -- including time intervals to pause, number of retries to attempt, timeouts for retrying -- are implementation dependent. Servers should be prepared to receive a POST with a repeated Message-ID. The MIME reply body previously sent should be resent, including the MDN and other MIME parts. 3. Other differences to notice in HTTP and SMTP based transport For HTTP version 1.1, TCP persistent connections are the default, ([HTTP] sections 8.1.2, 8.2, and 19.7.1). A number of other differences exist because HTTP does not conform to MIME [MIME] as used in SMTP transport. Relevant differences are summarized below. 3.1 Unused MIME headers and operations 3.1.1 Content-Transfer-Encoding not used in HTTP transport HTTP can handle binary data and so there is no need to use the Content transfer encodings of MIME [MIME]. This difference is discussed in [HTTP] section 19.4.4. 3.1.2 Epilogue must be empty The EBNF for a multipart [MIME] RFC 2046, section 5.1.1 allows a multipart to have trailing octets after the close delimiter. In [HTTP] section 3.7.2, it is explicitly noted that multiparts must have null epilogues. 3.1.3 Lengthy message bodies In [AS1], section 5.4.1, options for large file processing are discussed for SMTP transport. For HTTP, large files should be handled correctly by the TCP layer. However, [HTTP] sections Moberg, Brooks, Drummond [page 16] HTTP Transport for Secure EDI April 1, 2001 3.5 and 3.6 discuss some options for compressing or chunking entities to be transferred. Section 8.1.2.2 discusses a pipelining option that is useful for segmenting large amounts of data. 3.2 Differences in MIME or other headers or parameters used 3.2.1 Content-Length Because connections are persistent, closing a connection cannot be used to indicate the end of an entity. Therefore, [HTTP] sections 4.4 and 14.14 indicate the need for a Content-Length entity header in a request. 3.2.2 Final and Original Recipient The final and original recipient distinction should not arise for HTTP transport because SMTP aliases and mailing lists should not be used. 3.2.3 Message-Id and Original-Message-Id The Message-Id and Original-Message-Id distinction should not arise for HTTP transport because SMTP MTA alterations should not occur. 3.2.4 Host header The host request header field must be included in the POST request made when sending business data. This field is to allow one server IP address to service multiple hostnames, and potentially conserve IP addresses. See [HTTP], sections 14.23 and 19.5.1. Appendices A. AS 2 MIME templates Structure of an AS2 MIME message - PGP/MIME No encryption, no signature (analog of 4.2.1) -RFC2068/2045 -RFC1767/RFC2376 (application/EDIxxxx or application/xml) No encryption, signature (analog of 4.2.2) -RFC2068/2045 -RFC1847 (multipart/signed) -RFC1767/RFC2376 (application/EDIxxxx or application/xml) -RFC2015 (application/pgp-signature) Moberg, Brooks, Drummond [page 17] HTTP Transport for Secure EDI April 1, 2001 Encryption, no signature (analog of 4.2.3) -RFC2068/2045 -RFC1847 (multipart/encrypted) -RFC2015 (application/pgp-encrypted) -"Version: 1" -RFC2015 (application/octet-stream) -RFC1767/RFC2376 (application/EDIxxxx or application/xml) (encrypted) Encryption, signature (analog of 4.2.4) -RFC2068/2045 -RFC1847 (multipart/encrypted) -RFC2015 (application/pgp-encrypted) -"Version: 1" -RFC2015 (application/octet-stream) -RFC1847 (multipart/signed)(encrypted) -RFC1767/RFC2376 (application/EDIxxxx or application/xml)(encrypted) -RFC2015 (application/pgp-signature)(encrypted) Structure of an AS2 MIME message - S/MIME No encryption, no signature (analog of 4.3.1) -RFC2068/2045 -RFC1767/RFC2376 (application/EDIxxxx or application/xml) No encryption, signature (analog of 4.3.2) -RFC2068/2045 -RFC1847 (multipart/signed) -RFC1767/RFC2376 (application/EDIxxxx or application/xml) -RFC2633 (application/pkcs7-signature) Encryption, no signature (analog of 4.3.3) -RFC2068/2045 -RFC2633 (application/pkcs7-mime) -RFC1767/RFC2376 (application/EDIxxxx or application/xml) (encrypted) Encryption, signature (analog of 4.3.4) -RFC2068/2045 -RFC2633 (application/pkcs7-mime) -RFC1847 (multipart/signed) (encrypted) -RFC1767/RFC2376 (application/EDIxxxx or application/xml) (encrypted) -RFC2633 (application/pkcs7-signature) (encrypted) B.AS2 Extensions for the GISB Protocol and Report-type GISB AS2 Profile The United States based Gas Industry Standards Board (GISB) is a consortium of companies and individuals that operate in the Gas Industry. The membership is divided into 5 sectors, Producers, Pipelines, Services, End Users, Local Distribution Companies, Moberg, Brooks, Drummond [page 18] HTTP Transport for Secure EDI April 1, 2001 representing the various type of organizations within the industry. In 1996 GISB initiated a program to move from the expensive Value Added Networks they were using, to the Internet. By October of 1996 GISB had developed and tested a protocol, called GISB Electronic Delivery Mechanism (EDM), which uses HTTP and is based on RFC1867 (Form-based File Upload in HTML). By April 1997 this protocol was being used by Enron and others to send/receive live, mission critical business transactions over the Internet. Additional companies followed suit and a large percentage of today's business transactions in the Gas Industry are transmitted over the Internet using the GISB EDM protocol. In 1998 the Automobile Industry Action Group (AIAG) adopted the GISB EDM protocol and in 1999 the local electric companies serving the state of Pennsylvania declared the GISB protocol as their standard for transmitting business transactions via the Internet. In May of 1999 the AIAG, GISB and members of the IETF EDIINT workgroup initiated an effort to converge their independent specifications, the result of which is this specification. In order to bring the GISB EDM into compliance with this specification GISB initiated a formal change to the EDM specification. The following information, referred to as the "GISB AS2Profile", reflects the planned utilization of this specification by the GISB membership. The GISB membership will utilize PGP to meet all P.A.I.N. requirements. All data exchanges will utilize the multipart/form-data enveloping method and two generalized receipts, GISB-Acknowledgement-Receipt and GISB-Error-Notification. All original business transactions must be digitally signed (using encapsulated signatures) and encrypted using RSA algorithms. Upon successful transfer of an original business transaction the receiver is required to send a GISB-Acknowledgement-Receipt indicating that the transfer has completed successfully. If, upon further processing of the business document an error is encountered a GISB-Error-Notification is sent to the original sender using the multipart/form-data enveloping. It is expected that companies following the GISB AS2 profile will protect their web sites from unauthorized access through the use of basic authentication (username/passwords), as defined in the HTTP specification. GISB is not "requiring" the use of signed receipts; however, signed receipts are allowed between consenting trading partners. GISB has decided to use the following core headers: FROM: Contains the DUNS number of the sending party TO: Contains the DUNS number of the intended recipient INPUT-FORMAT: Type of data being sent (only x12 and error currently supported) other options can easily be added to this list. INPUT-DATA: The actual payload containing the business transaction or GISB-Error-Notification. If the payload contains a business transaction it is signed and encrypted using PGP. Moberg, Brooks, Drummond [page 19] HTTP Transport for Secure EDI April 1, 2001 Version: The GISB version number (currently 1.3) RECEIPT-DISPOSITION-TO: The DUNS number of the party to receive the GISB-Acknowledgement-Receipt (typically the same DUNS number associated with the From header.) Presence of this field also serves as a flag indicating that an acknowledgement receipt is requested by the sender. The receipt is returned synchronously (on the same session used to send the input-data payload). RECEIPT-REPORT-TYPE: Contains the value GISB-Acknowledgement-Receipt. Optional headers also available: TRANSACTION-SET: Identifies the type of transaction contained in the input-data payload. RECEIPT-SECURITY-SELECTION: This field serves as a flag indicating that a signed receipt is being requested. The contents of this field indicate the algorithm and signature type to use in constructing the signature. Example of a GISB data exchange: The sending party creates an X12 business transaction and concatenates with an RFC 1767 compliant header. The entire package is then encrypted and signed using PGP. The encrypted package is then enveloped with the appropriate headers/values and sent to the trading partner using HTTP POST, the contents of this post appear as follows: POST c:\execute HTTP/1.0 Referer: http://www.get.a.life/upl.htm Connection: Keep-Alive User-Agent: brow v0.1 XYZ Corp. Host: localhost Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, */* Content-type: multipart/form-data; boundary=---------------------------87453838942833 Content-Length: 5379 -----------------------------87453838942833 Content-Disposition: form-data; name="from" 123456789 -----------------------------87453838942833 Content-Disposition: form-data; name="to" 234567890 -----------------------------87453838942833 Moberg, Brooks, Drummond [page 20] HTTP Transport for Secure EDI April 1, 2001 Content-Disposition: form-data; name="Version" 1.3 -----------------------------87453838942833 Content-Disposition: form-data; name="receipt-disposition-to" 123456789 -----------------------------87453838942833 Content-Disposition: form-data; name="receipt-report-type" GISB-Acknowledgement-Receipt -----------------------------87453838942833 Content-Disposition: form-data; name="input-format" x12 -----------------------------87453838942833 Content-Disposition: form-data; name="input-data"; filename=c:\temp\smallnom.bin Content-Type: multipart/encrypted; boundary=8760; protocol="application/pgp-encrypted" --8760 Content-Type: application/pgp-encrypted Version: 1 --8760 Content-Type: application/octet-stream -----BEGIN PGP MESSAGE----- Version: PGP 6.5 hQCMAzRG1pEOIOvdAQP+JMr0m/9+8yOL60Z9Vr6fFV81FCExB/o0xmwiMkiwYsHs z0e8sb7ErC340MrNA/dw3taGMjmI+CXYRF/PLEdg1NZE1ZCtNeL4YdIHAMLWwODG lQxhSucz8rMSgQ5mZzcOJwBdWLW70efgsu/9UljuJjYc1uZ6C03eFQv/43fkB+al ATtgydxX4g8QK664ad+Jo/XUICSmWBL66fqJR1KLeLf4wTaqGy174Aq48Wpwvg1E h785zC03UAw0qg0ugMt86dPeyd91e2JigqwDYEf/DYEKD0J9BGiGpS/uAupNKj8O cp2IWClxKOGUbxpVNOnNTqWHS/GntegvDE/7/ewCxDxsnmQS95pOl141QZ1RQbeN aqx2Dq/ra9g65HNchOCzjul5Vi8HHf6Yhg2WnROe+npByyCue6rihqgNVOJwj0cV zpb4JE+gMDf3q4ISUb1Fv7/+SSFHDdnhdC5YTpqf1Bc3B07hiLmtTXqNit31EbX9 UVElObzSa9ZhxbC6/eSl7Nuf5ZTDsh9nrk+QQJ6FeC9W4cqXLj7IZySaRO8Vtff+ 4ktqeuhYusT4kSpnk027aw4O/5jomUkfb22CAe4= =Oiuo -----END PGP MESSAGE----- --8760- -----------------------------87453838942833 Upon receiving the above stream of data the receiving host parses the headers and returns an unsigned GISB-Acknowledgement-Receipt, appearing as follows: Content-Type: multipart/report; report-type="GISB-Acknowledgement-Receipt"; boundary="GISB7867" --GISB7867 Moberg, Brooks, Drummond [page 21] HTTP Transport for Secure EDI April 1, 2001 Content-type: text/html Acknowledgement Receipt Success

time-c=19960619082855* request-status=ok* server-id=coolhost* trans-id=234423897*

--GISB7867 Content-type: text/plain time-c=19960619082855* request-status=ok* server-id=coolhost* trans-id=234423897* --GISB7867-- C. Samples of AS 2 Protocol Data Units C.1 The following example illustrates the full HTTP request that sends X12 EDI data from company1 to company2. A signed receipt is requested; the receipt is to be a MDN report-type, with the pkcs7 signature option, using a signature algorithm of rsa-md5. The receipt is to be sent synchronously (that is, in the reply to this HTTP request), because no special delivery options are indicated. POST https://tp2server.company2.com/cgi-bin/tp1drawer.pl HTTP/1.1 Host: tp2server.company2.com To: tp2@company2.com Date: Tue, 06 Nov 2001 12:53:01 UT Subject: Purchase orders for 6 November 2001 Message-Id: <20011106@company1.com> Disposition-Notification-To: tp1@company1.com Disposition-Notification-Options: signed-receipt-protocol=optional, pkcs7-signature; signed-receipt-micalg=optional,rsa-md5 Content-Type: multipart/signed; boundary="20011106RsXgYlvCNW"; protocol=application/pkcs7-signature; micalg=rsa-md5 Content-Length: 3056 --20011106RsXgYlvCNW Content-Type: application/edi-x12 Content-Disposition: Attachment; filename=rfc1767.dat Content-Length: 2605 [ISA ...EDI transaction data...IEA...] --20011106RsXgYlvCNW Content-Type: application/pkcs7-signature Content-Length: 804 [omitted binary pkcs7 signature data] --20011106RsXgYlvCNW-- C.2 This second example illustrates returning a signed MDN that corresponds to the request for a MDN found in C.1. Moberg, Brooks, Drummond [page 22] HTTP Transport for Secure EDI April 1, 2001 HTTP/1.0 200 OK Server: HTTPEDI/1.1 Content-type: multipart/signed; boundary="boundary1" Content-Length: 1200 --boundary1 Content-type: multipart/report; boundary="boundary2" Content-length: 1133 --boundary2 Content-type: text/plain Content-length: 85 Message <20011106@company1.com> was authenticated; EDI processing was initiated. --boundary2 Content-type: message/disposition-notification Content-length: 213 Reporting-UA: Company2UA Final-Recipient: rfc822; tp2@company2.com Original-Message-Id: <20011106@company1.com> Received-Content-MIC: w7AguNJEmhF/qIjJw6LnnA==,rsa-md5 Disposition: MDN-sent-automatically/processed --boundary2-- --boundary1 Content-Type: application/pkcs7-signature Content-Length: 560 [ Signature data omitted] --boundary1-- D. Acknowledgments Carl Hage, Karen Rosenfeld, Chuck Fenton and many others have provided valuable suggestions improving this applicability statement. E. References [MIME] N. Borenstein, N.Freed, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, December 02, 1996. N. Borenstein, N.Freed, "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", RFC 2046, December 02, 1996. N. Borenstein, N.Freed, "Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples", RFC 2049 , December 02, 1996. [MIMEEDI] D. Crocker, "MIME Encapsulation of EDI Objects", RFC 1767, March 2, 1995. Moberg, Brooks, Drummond [page 23] HTTP Transport for Secure EDI April 1, 2001 [XMLTYPES] E. Whitehead, M. Murata, "XML Media Types", RFC 2376, July 1998. [SMTPMSG] D. Crocker, "Standard for the Format of ARPA Internet Text Messages", STD 11, RFC 822, August 13, 1982. (Also RFC 1123 provides important updates on date and time formats as well as email addresses.) [MIMEPGP] M. Elkins, "MIME Security With Pretty Good Privacy (PGP)", RFC 2015, Sept. 1996. [MDN] R. Fajman, "An Extensible Message Format for Message Disposition Notifications", RFC 2298, March 1998. [SECURITY] J. Galvin, S. Murphy, S. Crocker, N. Freed, "Security Multiparts for MIME: Multipart/Signed and Multipart/Encrypted", RFC 1847, Oct. 3, 1995 [SMTP] J. Postel, "Simple Mail Transfer Protocol", STD 10, RFC 821, August 1, 1982. [SMIMEV2] S. Dusse, P. Hoffman, B. Ramsdell, L. Lundblade, L. Repka, "S/MIME Version 2 Message Specification", RFC 2311. [SMIMEV3] B. Ramsdell, "S/MIME Version 3 Message Specification", RFC 2633, June 1999. [CMS] R. Housley, "Cryptographic Message Syntax", RFC 2630, June 1999. [REPORT] G. Vaudreuil, "The Multipart/Report Content Type for the Reporting of Mail System Administrative Messages", RFC 1892, January 15, 1996. [HTTP] R. Fielding, J.Gettys, J. Mogul, H. Frystyk, T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2068, January 1997. [AS1] T. Harding, R. Drummond, "MIME-based Secure EDI", Internet draft: draft-ietf-ediint-as1-10.txt. [TLS] T. Dierks,C. Allen, "The TLS Protocol Version 1.0" RFC 2246, January 1999. [FORMDATA] L. Masinter, "Returning Values from Forms: multipart/form-data", RFC 2388, August, 1998. [HTML] D. Raggett, A. Le Hors, I. Jacobs. "HTML 4.0 Specification", World Wide Web Consortium Technical Report "REC-html40", December, 1997. [GISB] Gas Industry Standards Board, "Electronic Delivery Mechanism Related Standards", Version 1.3 July 31, 1998 [MIME-TYPES] "Media Types," http://www.isi.edu/in-notes/iana/assignments/ media-types/media-types. [EDIINT] T. Harding, R. Drummond , "Requirements for Interoperable Internet EDI",Internet draft: draft-ietf-ediint-req.txt. Moberg, Brooks, Drummond [page 24] HTTP Transport for Secure EDI April 1, 2001 F. Security Considerations This entire document is concerned with secure transport of business to business data, and considers both privacy and authentication issues. G. Authors' Addresses Dale Moberg dale_moberg@stercomm.com Sterling Commerce 4600 Lakehurst Ct. Dublin, OH 43016 USA Dick Brooks dick@8760.com Group 8760 110 12th Street North Suite F103 Birmingham, Alabama 35203 Tel: 205-250-8053 Rik Drummond rik@drummondgroup.com Drummond Group 5008 Bentwood Ct. Ft. Worth, TX 76132 USA Moberg, Brooks, Drummond [page 25]