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EDIFACT message guide · Control and acknowledgments

AUTACK Secure authentication and acknowledgement

The UN/EDIFACT service message that authenticates interchanges or messages sent, or securely acknowledges those received.

Sent by
Sender or receiver of the secured data
Received by
The other party
Standard
UN/EDIFACT · Service message
X12 equivalent
No direct equivalent

What is the EDIFACT AUTACK message?

AUTACK is the UN/EDIFACT secure authentication and acknowledgement message. It authenticates interchanges, groups, messages or packages sent, or provides secure acknowledgement of those received. It can give secure authentication, integrity and non-repudiation of origin for the referenced data, or secure acknowledgement and non-repudiation of receipt.

AUTACK carries security results, such as hash values and digital signatures, separately from the business messages they protect. Today many partners secure transmissions at the transport level, for example with AS2, so AUTACK is used mainly where EDIFACT-level security is required.

How the EDIFACT AUTACK message worksDiagram of the UN/EDIFACT AUTACK Secure authentication and acknowledgement message. Sender or receiver of the secured data sends it to the other party. It usually starts the exchange. Inside the UNB and UNH envelopes, the directory D.21A requires, in the body and segment groups: the required SG1 loop with USH (Security header), USB (Secured data identification), the required SG3 loop with USX (Security references) and USY (Security on references) and the required SG4 loop with UST (Security trailer). 1 conditional segment groups are listed by their trigger segment.How the EDIFACT AUTACK message worksSecure authentication and acknowledgement: who sends it, where it fits and what the directory marksmandatory1 WHERE IT FITSUSUALLY FOLLOWSStarts the exchangeAUTACKSENDERSender or receiver ofthe secured dataRECEIVERThe other partyUSUALLY FOLLOWED BYNo business reply expected2 WHAT DIRECTORY D.21A REQUIRESInterchange: sender and recipient IDsUNB … UNZMessage AUTACKUNH … UNTBODY AND SEGMENT GROUPSMandatory group SG1 · repeats up to 99USHSecurity headerUSBSecured data identificationMandatory group SG3 · repeats up to 9,999USXSecurity referencesUSYSecurity on referencesMandatory group SG4 · repeats up to 99USTSecurity trailer+ 1 conditional group, starting with:USCBlue box: mandatory segment group. Conditional groups are listed by the trigger segment that starts them; a group is sent only when its data applies.Conditional segments outside groups are not drawn.Structure: mandatory segments and groups in the UN/EDIFACT directory D.21A listing for AUTACK. Your trading partner's implementation guide adds itsown requirements.
How the EDIFACT AUTACK message worksDiagram of the UN/EDIFACT AUTACK Secure authentication and acknowledgement message. Sender or receiver of the secured data sends it to the other party. It usually starts the exchange. Inside the UNB and UNH envelopes, the directory D.21A requires, in the body and segment groups: the required SG1 loop with USH (Security header), USB (Secured data identification), the required SG3 loop with USX (Security references) and USY (Security on references) and the required SG4 loop with UST (Security trailer). 1 conditional segment groups are listed by their trigger segment.How the EDIFACT AUTACKmessage worksSecure authentication and acknowledgement:who sends it, where it fits and what thedirectory marks mandatory1 WHERE IT FITSUSUALLY FOLLOWSStarts the exchangeAUTACKSENDERSender orreceiver of thesecured dataRECEIVERThe other partyUSUALLY FOLLOWED BYNo business reply expected2 WHAT DIRECTORY D.21A REQUIRESInterchange: sender and recipient IDs(UNB … UNZ)Message AUTACK (UNH … UNT)BODY AND SEGMENT GROUPSMandatory group SG1 · repeats upto 99USHSecurity headerUSBSecured data identificationMandatory group SG3 · repeats upto 9,999USXSecurity referencesUSYSecurity on references+ required SG4 (UST) and 1 conditionalgroup, starting with:USCBlue box: mandatory segment group. Conditionalgroups are listed by the trigger segment thatstarts them; a group is sent only when its dataapplies. Conditional segments outside groups arenot drawn.Structure: mandatory segments and groups in theUN/EDIFACT directory D.21A listing for AUTACK.Your trading partner's implementation guide adds itsown requirements.

How to read this diagram: the top row shows who sends AUTACK, to whom, and which messages usually come before and after it. The lower part shows what the directory D.21A itself requires: the envelopes around AUTACK and the segments and segment groups it marks mandatory. Conditional groups are listed by their trigger segment rather than drawn in full. This is the directory's minimum, not a trading partner's requirement: a message implementation guide usually makes some conditional groups mandatory, restricts the codes and may use an older directory.

Expand diagram Download SVG

When it is used

  • Signing EDIFACT messages for non-repudiation
  • Securely acknowledging receipt of signed data
  • Meeting sector rules for message-level security

Where it fits in the message flow

This message AUTACK Secure authentication and acknowledgement

No other message routinely comes directly before or after AUTACK; it is exchanged when the business event occurs.

Structure

Mandatory segments in AUTACK (directory D.21A)

In UN/EDIFACT directory D.21A, the AUTACK message has 12 segment positions arranged in 4 segment groups. These are the segments and segment groups marked mandatory at message level, in order; a mandatory group is shown with the segment that starts it. Segments inside conditional groups are needed only when the group is used. This is the directory’s requirement; earlier syntax versions define the message differently, and partners agree which version they use. This structure comes from one published copy of the directory and has not been independently verified: confirm it before you build a map.

  • UNH
  • SG1 (USH)
  • USB
  • SG3 (USX)
  • SG4 (UST)
  • UNT

Practical example

AUTACK in practice

A bank requires message-level signatures on payment files from corporate clients. The client's EDI system sends each PAYMUL followed by an AUTACK containing the hash of the message and the client's digital signature. The bank verifies the signature before processing and returns a secure acknowledgement.

Implementation

Implementation considerations for AUTACK

  • Agree algorithms, certificates and key management with the partner.
  • Decide whether transport-level security already meets the requirement.
  • Manage key and certificate expiry, for example with KEYMAN.
  • Keep secured data and acknowledgements for non-repudiation evidence.

How ECOM helps

Automate AUTACK with ECOM

Solution

B2B Integration

Connect every customer, supplier, carrier and bank across EDI, API, file and portal channels.

Solution

Managed File Transfer

Design, migrate and operate secure, auditable file exchange across partners and systems.

Industry

Financial Services

Secure file transfer and B2B integration for banks and financial institutions.

Compare X12 and EDIFACT, or see answers to general questions in the EDI FAQ.

Related messages

Related control and acknowledgments messages

All 4 control and acknowledgments messages

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