MFT Resource Center

Applicability Statement 3 Protocol (AS3)

What is AS3?

AS3 is an MFT/EDI protocol built on File Transfer Protocol (FTP). Since the 1960s, companies have used FTP to send data, including EDI data, across the Internet to partners. The problem is FTP is unsecured. AS3 adds MDNs, similar to AS1, to provide verification known as non-repudiation. It also enables organizations to securely send and receive XML documents, in addition to MFT documents. AS3 enables push and pull FTP capabilities, similar to setups in asynchronous and bi-synchronous environments.


The IETF developed AS3 in 2006.

AS3 Status and Popularity

AS3 is used across industry, for many companies that use FTP. But it's not nearly as popular as AS2 or AS4, largely because for FTP-based transfers, most organizations prefer to use SFTP.

AS3 Security

AS3 provides tight security on par with that of AS2 by implementing MDNs in combination with encryption. This 1-2 punch of digital signatures and encryption makes AS3 more secure than both traditional FTP and File Transfer Protocol Secure (FTPS), which uses Secure Sockets Layer (SSL) in combination with FTP. It improves on the way FTPS encrypts data by allowing firewalls to inspect the flow of network traffic.

Who Uses AS3?

Organizations worldwide that use FTP in their technology framework use AS3. It's particularly important for organizations with a sizable IT investment in FTP scripting, applications or security. It's even useful for many financial and healthcare organizations that need to send highly sensitive information via MFT and want to use FTP.