Comment by rtpg

>Supposing you do hit the lottery and get a key somewhere in your packet, you now have to find the starting byte for it, which means having data to attempt to decrypt it with. However, now you get bit by the fact that you don't have any privileged information or credentials, so you have no idea where decryptable information lives.

Login page of any SaaS will be transmitted over SSL and you'll know what it looks like a priori.