I want to display some very sensitive information on a web page and I want to make sure that nobody, except the user in front of the browser, is able to access this information. I'm aware that in general is it not a good idea, but some site manage to do it. For example : LastPass
What are the security risk to consider?
How would you proceed to implement it securely?
Assume that the client computer is not compromised and that it's the client problem to be sure no on else is looking above his shoulder.
Now, if you are going to just reply "NO", just don't. It's clearly possible because some site are doing it or are you saying that they are all unsafe? If this is the case, could you please elaborate?
And, before anyone flag this question as duplicate, I just asked the same thing here but it didn't receive any good answer and the question was put on hold, maybe because I didn't formulate the question correctly.
Also, if anything is not clear in the question, please leave a comment below and I will answer it.