Error MDNs stating an error in the lines of "Signature verification failed" or "Decryption failed" are common for users who are just getting started AS2 in any AS2 service. We, ourselves, have seen many such instances in our SaaS B2B AS2 messaging platform the AdroitLogic AS2Gateway. With these kinds of errors, sometimes, it is important for the support team and also the user itself to be able to try the decryption or signature verification manually to get more insight.
In this blog post, we will look at what the digital signature in AS2 protocol is, how to verify the signature of an AS2 message, and some tips on figuring out the cause for certain signature verification failures.