A Brief History of NSA Backdoors. posted February 2015
here's an entertaining piece about NSA backdoors through history: http://ethanheilman.tumblr.com/post/70646748808/a-brief-history-of-nsa-backdoors
1997 Lotus Notes: The NSA requested that Lotus weaken its cryptography so that the NSA could break documents and emails secured by Lotus notes. This Software was used by citizens, companies and governments worldwide.
I talked about this one here.