During the "troubles" in Northern Ireland, the British Army operated a laundry - an apparently innocent laundry with some additional hidden functionality - checking dirty clothes for traces of explosive. [Washington Post via Bruce Schneier]
In my earlier post Services Like Laundry I said "I do not expect the laundryman to draw any inferences from the state of my clothes, or to pass these inferences to anyone". Clearly the actions of the British Army would count as a breach of this kind of expectation, but this would be justified by its effectiveness as a clever counter-terrorism measure. However, laundries might well test for various other substances, or test the DNA of any stains on the clothing, for a broad range of purposes other than counter-terrorism.
So what's the lesson from this? Basically, if you have any illicit substances or just embarrassing stains on your clothing, you can't trust the laundry service not to notice. And you certainly can't specify this not-noticing as part of the service contract - what are you going to do, draw the laundryman's attention to the thing he isn't supposed to notice?
And what if the laundryman noticed your shirts were getting a little frayed about the collar, and sold your address, together with details of your designer-label preferences, to a mail order shirt supplier? You might think this was unreasonable if you knew about it, but you would probably never find out. You might receive a mailshot from the shirt supplier, but you probably wouldn't connect it with the laundryman. (One possible mechanism for tracing abuse of your name and address is to give slightly variant names and addresses to every supplier, but lots of organizations nowadays have clever data cleansing software that wipes out these variations.)
How does this apply to other kinds of service? If I use CRM-as-a-service, how can I prevent my service provider picking up information about my customers? If I use a third-party delivery service, how can I prevent the service provider selling details of my customers and their purchasing habits to my competitors? How can I even specify this as part of the service level agreement?
WS Security standards cover some aspects of confidentiality and trust, but this merely relates to the security of a message in transit (at the technology level), and not to the broader questions of confidentiality and trust between two parties (at the enterprise level).
According to legend, the automatic telephone exchange was invented by an undertaker (Almon Strowger) who believed his business was being redirected to his competitors by corrupt telephone operators. (See Call Forwarding.) So this suggests a possible answer to this difficulty is to redesign the service architecture to reduce the enterprise vulnerability, supported by more sophisticated technology. For example, does your CRM provider really need unencrypted names and addresses, or can you pass your customer data through an encryption module?
So what's the lesson from this? You need an enterprise view of trust and security that is supported by (aligned with) a technology view of trust and security. The relationship between these two views is tough.