If you want to think about moral concepts that ground debates about privacy, you can't help but think about trust. The basis of a community is the trust that the members extend to one another: the trust that we will leave each other in peace, respect one another as human beings, and (hopefully) look out for one another's welfare. Democratic political institutions rely on citizens' trust that fair and open procedures create just societies. Without the possibility of trust, we lose all society, and all social philosophy.
Trust is also an important concept in security. We employ security out of a lack of trust. We trust the designers of our security and encryption systems. Citizens encrypt their data or web traffic because they do not trust the government. The government resists citizen use of strong encryption because they do not trust the citizens.
It might be easy to conclude that with sufficient trust, we would have no need for security or encryption. I think there are independent reasons to value privacy, so let's no go quite that far. Instead, we might understand the practice of exchanging security credentials as demonstrations of trust. When I present my username paired with my password, I demonstrate that I have trusted access to the account. When a firm hires a new employee and creates security keys and access codes, the new employee is being initiated into a web of trust.
In many cases, we connect trust to identity. A security key demonstrates the identity of the holder, for instance. Certainly, the sense of trust that grounds a community seems connected to recognizing one another as neighbors. Nevertheless, we have a large anonymous community organized around activism, not to mention the mostly anonymous BBS and Usenet communities that formed in the early days of the online world.
The information economy also runs on trust. If users can trust information vendors to protect their private data, users are more likely to enter into the information market. In the US, information vendors have to rely on reputation and user-friendly privacy policies. The results are somewhat mixed, even more so since the PRISM leak. Some users just don't trust Big Data, and established trust can wane due to current events or changing attitudes.
So what do we do about this? Well, stay tuned...