What is X.509 Digital Certificate?

EDI & B2B Protocols

X.509 Digital Certificate

A public key certificate used to authenticate trading partners and encrypt/sign data in AS2 and AS4 connections. Each AS2 trading partner relationship requires exchanging X.509 certificates. Certificate expiration — typically every one to three years — is a common cause of sudden AS2 connectivity failures.

Why X.509 Digital Certificate matters in B2B integration

X.509 Digital Certificate is part of the edi & b2b protocols vocabulary that operators, IT leaders, and integration architects use when scoping ecommerce, ERP, EDI, and fulfillment projects. APIWORX integrates 200+ systems across this landscape — if X.509 Digital Certificate touches your stack, we can help you connect it without custom code.

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AS2Applicability Statement 2

The most widely adopted protocol for direct, secure EDI transmission over the internet. AS2 uses HTTP/HTTPS with digital signatures (non-repudiation), encryption, and MDN delivery confirmations. Mandated by most major US retailers — including Walmart, Target, Home Depot, and Amazon Vendor Central — and requires exchanging X.509 certificates with each trading partner.

AS4Applicability Statement 4

The successor to AS2, built on the OASIS ebMS 3.0 standard and SOAP/HTTP. AS4 adds improved reliability, large payload support, and flexible security profiles. Increasingly required in European and global trade networks, including the Peppol network for government e-invoicing across the EU and beyond.

AS1Applicability Statement 1

The original AS standard for secure EDI over SMTP (email). AS1 predates AS2 and is largely obsolete in modern trading networks, though it may still appear in legacy supplier connectivity requirements.

SFTPSSH File Transfer Protocol

A secure file transfer protocol that encrypts both authentication and data transfer channels using SSH. SFTP is one of the most common EDI transmission methods — particularly for batch file-based trading relationships, 3PL connectivity, and legacy ERP integrations. Unlike AS2, SFTP does not provide built-in message-level acknowledgment or non-repudiation.

FTP / FTPS

FTP (File Transfer Protocol) is the original unsecured file transfer standard — largely deprecated due to lack of encryption. FTPS adds TLS/SSL encryption. Some legacy trading partners still require FTPS, but SFTP is the preferred successor for all new implementations.

HTTPS / REST API

HTTP Secure with TLS encryption is the universal transport for modern API-based B2B integrations. REST APIs over HTTPS are now the dominant connectivity method for marketplace, ecommerce, and SaaS-to-SaaS integrations — enabling real-time, event-driven data exchange. HTTPS APIs are displacing traditional EDI in new trading relationships while coexisting with EDI in established retail networks.