AS1 Transport

This chapter describes how to use AS1 Transport for document exchange.

AS1 Transport Overview

AS1 (Applicability Statement 1) is the name given to implementations of RFC 3335 (MIME-Based Secure Peer-to-Peer Business Data Interchange Over the Internet) from the IETF (Internet Engineering Task Force). AS1 involves the exchange of documents over the internet using S/MIME and SMTP.

AS1 and AS2 are widely recognized standards for the exchange of documents between businesses: these standards allow users to exchange data securely and reliably using the internet. This results in reduced costs for users by eliminating the need for VANs (Value Added Networks).

To date over 25 different companies offer products which support AS1 or AS2 or both. These products have all undergone interoperability testing which is facilitated by Drummond Group Inc. and are certified by eBusinessReady as being interoperable.

AS1 transport supports:
  • Documents signing
  • Documents encryption
  • Documents compression

AS1 Transport

AS1 Transport, hereafter referred to as AS1 Email transport, allows you to exchange documents over the Internet using S/MIME and email. It only specifies how to connect to a trading partner, deliver data, and get a receipt in a secure manner.

When data is transmitted to a trading partner using normal email such as Outlook email, a MIME content-type of text/plain is normally used. The content-type application/xml is used for sending XML documents.

It might not be possible for a trading partner using email to communicate successfully to a trading partner using AS1 email. The trading partner using AS1 email expects to receive messages that use the AS1 content-types. That trading partner also sends messages using these content-types.

A trading partner using email might not recognize these AS1 content-types and therefore might not be able to process the email messages.

Message Compression

If a trading partner can send email messages according to the IETF AS1 standard (rfc3335.txt) and the trading partner’s AS1 product has passed interoperability testing with the Drummond Group, compression is available for large email messages. There are different algorithms that can be used for compression of MIME messages. The Drummond Group AS1 interoperability test specification calls for a particular specification (draft-ietf-ediint-compression-12) to be followed when doing compression.

For large messages, compression is highly recommended. Do not use compression on smaller messages, as this might create a compressed message that is larger than the original message.

Attachments

The AS1 Email transport supports the sending and receiving of attachments as part of an AS1 message. This support is outside of the scope of the AS1 specification and might not be supported by other E-commerce vendors who offer AS1 support in their products. When attachments are added to an AS1 message, a multipart/mixed MIME message is created. The first body part of the MIME message will contain the main document, while the subsequent body parts will contain the attachments.

When an AS1 message with attachments is signed, the entire multipart/mixed MIME message is signed. Likewise, when an AS1 message with attachments is encrypted, the entire multipart/mixed MIME message is encrypted.

When an AS1 message is received that contains a multipart/mixed MIME message, the first body part is processed as the main document, while the subsequent body parts are processed as attachments. All inbound attachments are saved onto the file system and their file references are passed to the private process.

Not all TIBCO BusinessConnect Container Edition protocols support sending attachments with the AS1 Email transport. Those protocols which have support for passing attachment information in their messages to or from the private process can be used to send attachments with the AS1 Email transport. See the User's Guide of your TIBCO BusinessConnect Container Edition protocol to see whether it supports sending attachments with the AS1 Email transport.

Content Disposition Filename

Some back-end systems require that data to be processed be stored in files with particular filenames. Therefore, for some trading partners it might be necessary to associate filenames with the content of messages that was sent to them. For AS1 messages, this can be achieved by specifying the filename to use for storing the message content in the filename parameter of the Content Disposition header.

Some TIBCO BusinessConnect Container Edition protocols also provide the ability for the private process to specify a filename to be used as the value of the filename parameter in the Content Disposition MIME header of outgoing MIME messages, including AS1 messages. The filename can be specified for the Content Disposition header associated with the main document and/or any attachments. TIBCO BusinessConnect Container Edition protocols which support specifying the filename value for the Content Disposition header will also pass the value of the filename parameter from the Content Disposition header of inbound AS1 messages to the private process.

See the User's Guide of the TIBCO BusinessConnect Container Edition protocol you are using to see whether it supports passing the Content Disposition header filename to/from the private process.

Options for Configuring AS1 Email for the Trading Partner

To use TIBCO BusinessConnect Container Edition AS1 Email Transport, select the AS1 Email transport when configuring your trading partner. The following options are available:
  • Authentication Supported through digital signatures.
  • Security Supported through message encryption.
  • Non-repudiation Supported through digital signatures and email receipts.
  • Compression Supported through the compression option as specified in the draft-ietf-ediint-compression-12 specification.

Message Digest Algorithm

The AS1 specification, RFC 3335, recommends that the SHA-1 hash algorithm be used to calculate the message digest for all outbound messages. By default, the TIBCO BusinessConnect Container Edition AS1 transport will always use the SHA-1 hash algorithm regardless of the Digest Algorithm setting for the business agreement.

To override the default use of SHA-1 for the hash algorithm by the AS1 transport, you can set the TIBCO BusinessConnect Container Edition property bc.ediint.digestAlgorithmEnabled as follows:
  • If bc.ediint.digestAlgorithmEnabled is set to true, the AS1 transport will use the digest algorithm that is specified in the business agreement Document Security settings.
  • If bc.ediint.digestAlgorithmEnabled is false, the default, the AS1 transport will ignore the digest algorithm setting in the business agreement and use SHA-1.

Use of the MD5 hash algorithm with AS1 should not be required.Drummond Group certified AS1 products all use SHA-1 for the hash algorithm during interoperability testing. However, the AS1 specification also states that AS1 products should be able to accept messages which use the SHA-1 hash algorithm. TIBCO BusinessConnect Container Edition will process inbound messages using either hash algorithm.

Note: Inbound AS1 messages that do not contain a content-type of application/x12, application/edifact, or application/consent cannot be determined to be AS1 email messages as opposed to plain email messages. Therefore, when an inbound email message is received that requests a signed receipt, the message digest for the email will be calculated using the Digest Algorithm setting of the business agreement regardless of how the email was sent (AS1 or plain email).

Identifying the Sender and Receiver

The AS1 Email transport uses standard To and From email addresses as defined in SMTP standard (RFC 2821). These email addresses are defined in the Valid Email Address List field in the Partner Management > Partners > Partner Name > Protocol> Edit Configurations > General. When email is received from the mail server:
  • The To address is matched against the email address entered in the host’s Valid Email Address List.
  • The From address is matched against the trading partner’s Valid Email Address List.