AS2, AS3, and AS4 Transfers

What are the Applicability Statement protocols and how are they used to send and secure critical file transfers? Explore everything you need to know about the Applicability Statements AS2, AS3, and AS4.

What is AS2?


AS2 (Applicability Statement 2) is a popular protocol specification for transporting critical data securely and reliably over the internet.

Upgraded from the original protocol (AS1) that was created in the 1990s, the AS2 protocol supports the encryption of messages (also known as AS2 messages) that are then exchanged with trading partners and vendors via HTTPS. These messages are built using the S/MIME format.

How Does the AS2 Protocol Work?


AS2 utilizes digital certificates and encryption standards to protect critical information while it’s in transit across systems, networks, and locations. AS2 messages can be compressed, signed, encrypted, and sent over a secure SSL tunnel.

Users can also request an MDN (known as Message Disposition Notification; also sometimes referred to as "receipt") alert to verify that the message was received and decrypted successfully. Using signed receipts to compare the returned message checksum value creates a non-repudiation of receipt (NRR). An NRR gives the sender legal proof of unaltered delivery.

MDNs can be delivered in a variety of ways, including:

Synchronous MDN

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This option allows the AS2 server connection to remain open until an MDN is received or a timeout occurs.

Why Use AS2?


Using the AS2 protocol comes with unique advantages that ensure the streamlining of critical data exchange. These advantages include end-to-end encryption, strong authentication of senders and recipients through the use of digital signatures, and validation of file integrity with successful transfer confirmation.

AS2 is a secure industry standard protocol for sending sensitive data. Organizations who use AS2 often choose it over other file transfer protocols (like FTP or SFTP) because of how easily the protocol helps them meet regulatory compliance requirements and trading partner needs.


Benefits of AS2 & AS2 Software

End-to-end encryption for sensitive files

Authenticating senders and recipients with digital signatures

Validation of file integrity with successful transfer confirmation

Ability to send/retrieve file transfers of any size or volume

Flexible support for synchronous or asynchronous MDN receipts

Improve Your File Transfers with GoAnywhere's AS2 Protocol Solution

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AS2 Client Software & Server

AS2 Client

The AS2 client software in GoAnywhere can automate the delivery of AS2 messages or send AS2 messages on a scheduled basis. It can automatically reconnect to the server if a connection breaks and retransmit the message. Both synchronous and asynchronous receipts can be logged to ensure AS2 messages were successfully processed by the trading partners.

Learn more about our AS2 client software >

AS2 Server

The AS2 server software in GoAnywhere allows you to receive AS2 messages. Your trading partners can be authenticated using a combination of user credentials and X.509 certificates. When a message is received, you can have a trigger automatically process the received files. For instance, GoAnywhere could move the AS2 documents to another area on the network or call an application to process these files.

Learn more about our AS2 server software >

Drummond Certification


Drummond Certified is a label that the Drummond Group (a third-party certification body) gives to products and solutions that have proven their interoperability between AS2 vendors. The certification is extensive and helps ensure that the solution you use will allow you to successfully integrate with your AS2 trading partners.

In order to pass the Drummond Certification process, any product attempting certification must conduct thousands of AS2 protocol test scenarios successfully in the Drummond Group's controlled, vendor-neutral environment. This process uses full matrix interoperability testing between AS2 vendor solutions to verify that important transactions maintain their security and integrity as they are transmitted over the Internet.

GoAnywhere MFT is Drummond Certified™ for AS2 and AS4


GoAnywhere MFT is a Drummond Certified solution for both AS2 and AS4, which helps to ensure successful integration with your AS2 or AS4 trading partners. The Drummond certification process uses full matrix interoperability testing between vendor solutions to verify important transactions maintain their security and integrity as they are transmitted over the Internet. In order to pass the Drummond Certification process, GoAnywhere MFT conducted thousands of AS2 and AS4 protocol test scenarios successfully. This certification provides customers with peace-of-mind that GoAnywhere can handle their most critical AS2 and AS4 documents.

Simplified Administration

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GoAnywhere MFT provides a browser-based interface for configuring and monitoring AS2, AS3, and AS4 protocol file transfers and workflows. Each administrator can be assigned different permissions in GoAnywhere with their own custom dashboards.

  • Configure AS2/AS3/AS4 file transfers and workflows using graphical wizards
  • Set up AS2/AS3/AS4 trading partners quickly
  • Easily create, import, and export X.509 certificates with AS2/AS3/AS4 certificate exchange
  • Receive automatic status alerts on AS2/AS3/AS4 transfers
  • View AS2/AS3/AS4 audit logs and analytical information
  • Exchange sensitive EDI and EDI X12 files with AS2/AS3/AS4 trading partners

Learn more about the GoAnywhere MFT Administrator >


AS2 Client Software Features

Fully automates AS2 protocol transfers with an integrated scheduler

Provides graphical wizards to set up AS2 trading partners quickly

Encrypts messages and files using strong AES-256 bit encryption

Guarantees delivery with auto retry and auto-resume

Supports synchronous and asynchronous receipts

Can be scaled to handle unlimited AS2 partners

Generates detailed audit logs of all AS2 transfers

Securely transfers EDI and EDI X12 files between businesses

Getting Started with AS2 File Transfers

Whether your trading partners require you to send files using AS2 or you’re looking for an industry standard protocol to transmit sensitive files that meet regulatory compliance, it’s easy to implement AS2 in your organization. You just need the right solution.

GoAnywhere MFT is a secure managed file transfer solution that simplifies, streamlines, audits, and automates your file transfers across a variety of environments. It provides AS2 client and AS2 server software for small, medium, and enterprise-level organizations.


AS2 Tutorials

Learn how to transfer AS2 files with GoAnywhere MFT

Learn how to get started with file transfer services, such as FTP, FTPS, SFTP, HTTPS, AS2, and GoDrive.

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Learn the process to create an SSL certificate, have the certificate signed by a certificate authority, and assign the certificate to the HTTPS service.

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The AS2 client is used to automate the transfer of data with an AS2 service. Learn how to configure the AS2 client in GoAnywhere MFT, create a Project to send an AS2 message, and then process the MDN receipt.

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Applicability Statement 2 (AS2) is a method used to securely send files over the internet. Learn how to configure AS2 in GoAnywhere MFT to enable encryption, signatures, compression and the use of receipts for delivery confirmation.

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After your AS2 Service is configured, you need to provision user accounts to access the service. Learn how to create and configure Web Users in GoAnywhere MFT that are used to transfer data using AS2.

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We were looking for an off-the-shelf implementation of an AS2 Server and Client that we could easily integrate with our systems on AWS [Amazon Web Services.] GoAnywhere was the perfect match.

Executive Sponsor G2 Review

What is AS3?


AS3 (Applicability Statement 3) is a standard used to securely transmit virtually any file type. It was originally created to transfer structured data files, like XML and EDI documents, for business-to-business data sent over FTP(S). These messages are structured using the standard S/MIME format.

When and Why to Use AS3

AS3 is a secure protocol for sending sensitive data. Organizations using AS3 often choose it over other common file transfer protocols (like FTP or SFTP) because it simplifies the process to meet compliance requirements and trading partner needs.

Users can request MDNs (Message Disposition Notifications), or receipts to verify that the intended AS3 message as received, either as signed or unsigned.


Benefits of AS3

End-to-end encryption for sensitive files through SSL

Transaction records and audits

Delivery receipts and MDN

What is the Difference Between AS2 and AS3?


While AS2 is a transfer protocol, AS3 is a message standard that focuses on message formatting. Where the AS2 protocol requires a dedicated AS2 server and client to send messages, AS3 is flexible: once an AS3 message is composed, it can be transmitted via any other protocol – FTP, SFTP, HTTPS, and more – as long as both the sender and recipient can access the message’s location. Also unlike AS2, AS3 is a push-pull protocol and does not require an ongoing connection.

Keep reading >  

The AS3 Client


The AS3 client software in GoAnywhere can automate the delivery of your AS3 messages, send on a schedule, or send based on triggers. With GoAnywhere, you can:

  • Attach multiple files to a message
  • Digitally sign all outgoing messages
  • Receive message receipts either automatically or manually
  • Log all AS3 message traffic – what was sent, by who, and date and time

Learn more about our AS3 Client

What is AS4?


AS4 is a popular file transfer protocol that gives businesses the ability to securely exchange data with their partners. It builds on the foundations set by AS2 to improve security, reliability, and flexibility for delivering and receiving messages. As a Business-to-Business standard, AS4 makes exchanging documents over the internet simple and secure.

How Does AS4 Work?

AS4 is payload agnostic and can also send multiple payloads in one AS4 message. Unlike AS2, AS4 is based on SOAP and Web Services, which many organizations use, making it more compatible with standard environments.

Why Use AS4?

AS4 is a secure B2B and B2C method for exchanging data: encryption, large file transfers, and are managed for you with AS4. AS4 is an EDI-friendly protocol and is sometimes adopted in EDI communities to simplify EDI integration projects.


Benefits of AS4

Messages sent via AS4 cannot be modified in transit without the change being detected

Non-repudiation means that both the sender and the recipient receive records of the data movement

Reliable delivery includes confirmations and ensures a one-time delivery. If a message fails, AS4 will re-send


What’s the Difference Between AS2 and AS4?

AS2 and AS4 are both popular file transfer protocols that allow businesses to exchange data securely with their business partners. AS4 builds on the best of AS2, but works with web services and provides improved delivery notifications.

Keep reading > 

What's the Difference Between AS3 and AS4?

While AS3 and AS4 may not have much in common besides their names, just what makes them so different? Discover the history of these two protocols, and how they work to improve file transfers in different ways.

Keep reading > 

The AS4 Client


The AS4 client software in GoAnywhere can automate your workflows and improve your file transfers. Compress, sign, and encrypt your messages to ensure utmost security, and monitor your data transfers easily with receipts for messages sent and received, as well as with logging.

Learn more about our AS4 Client 

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