The lineage function is a great tool for users to understand how items are calculated. Business users can use it to fully understand what they’re seeing. The downside of the lineage is that users can fully understand what they’re seeing.
To the best of my knowledge there is no way of telling Cognos to obfuscate a step in the lineage path. This can cause problems if, for example, you use Cognos functions to decrypt a numeric value.
Case in point: an unnamed large company has a field called “Encrypted Data”. The users need to be able to build adhoc queries with the data, but they are not allowed, under any circumstances, to know the decryption formula. A custom database function is out, so it can only be done in Cognos. The users have a tendency to use lineage to double check numbers.
As you can see, lineage leaves a gaping hole in security. Fortunately there is a solution.
The first step is to create a calculation in FM that decrypts the field.
In the properties of the calculation set Is Hidden to true.
Next create a parameter map. Call it Decrypter.
Give it a key. Since the example I’m using is based on the orders table, I gave it the key Order. In the value give it the path of the calculation.
Now for the last step. In the business layer instead of calling the calculation directly you’ll call the parameter map with ‘Order’ as the key.
Now when the user tries to peek in at the lineage he sees this:
Instead of seeing the super secret formula, he only sees the call to the param map. If he doesn’t have access to FM, he will never be able to see the formula now.