Trade-Offs When Protecting Secret Data

Like everything in the world of software development, building secure systems is all about making trade-offs. The most significant trade-offs you need to consider when building applications that store secrets are as follows:

Relative security
Effort required to develop such an application
Ease of deployment

Personally, I think if you need to protect data, then you need to protect data regardless of the development cost. A little extra time spent in development getting the solution right will save time and money in the future. The big trade-offs are relative security versus ease of application deployment. The reason should be obvious: if some data is secured, it's probably not very deployable! Table 9-1 offers a high-level view of the relative costs of the different data protection techniques; you should use it as a guideline.

Table 9-1. Trade-Offs to Consider When Protecting Secret Data
Option	Relative Security	Development Effort	Deployment Ease
Configuration files (no encryption, for comparison only)	None	Low	High
Embedded secrets in code do not do this!	None	Low	Medium
COM+ construct strings	Medium	Medium	Medium
LSA secrets	High	High	Low
DPAPI (local machine)	High	Medium	Low
DPAPI (user data)	High	Medium	Medium