The invention provides a system and a method which utilizes a combination of message-based encryption and message-based digital signing to ensure the security and authenticity of a message or message buffer sent from one party or process to another in a transaction processing system. In one embodiment the invention includes a method comprising the steps of: creating an encryption envelope by encrypting a message buffer, signing the encrypted contents of said message buffer with a digital signature, sending said encryption envelope from the sender process to the recipient process, receiving the encryption envelope at the recipient process, decrypting said encryption envelope to retrieve said message, and verifying the identity of the sender process by retrieving the digital signature from the encryption envelope. The invention allows intermediate recipients to inspect the message, and provides for reliable authentication, confidentiality, integrity, and non-repudiation, of communicated messages.