I am confused about the exact requirements in business connector for send an XML file from A to B using HTTPS.

In the past we have given our partners our Certs, and they give us their certs and we each install each other’s certs on our respective Business Connector systems.

I am just wondering if this is really required for HTTPS, or if only the receiver is required to give certs to the sender if the comms is just one way? Does the sender even need their own certificates if they will only ever be sending?

Matthew,
As you may know that HTTPS is running HTTP over SSL. Several comms steps (SSL handshake) are performed between the server (party that received the original request) and the client (party that initiated the original request) before an actual HTTP data flow. The default and the most commonly used SSL/HTTPS mode requires only the authentication of the server machine/party during the handshake. Thus the server machine/party certificate is the only requirement in most SSL connections.
For added security SSL also supports bi-directional authentication/SSL client side authentication in which the server can also request/ask the client to be authenticated as well and thus would require the client party to have a key/certificate pair as well.

In summary, if the SSL/HTTPS server is configured for Client authentication then the sending party would also need key/vertificate pair as well else only the server needs to have the certificate installed.
Btw, the certificates on both ends have to be trusted/known by both parties.

~tS