> Can someone give an example as to how a software made up of secure > functions can be hacked?
The security depends not only on the program but on your requirements and the environment where it is used. https://bad-example-find-xargs-rm.s3.eu-west-2.amazonaws.com/find_xargs_rm.html There's the whole subject of side channels where computers are bad at keeping secrets. On scoring high at the wrong task I recommend: https://www.cl.cam.ac.uk/archive/rja14/Papers/wcf.pdf Books: Schneier: Secrets and Lies https://www.amazon.com/Secrets-Lies-Digital-Security-Networked/dp/0471453803/ Anderson: Security Engineering https://www.amazon.com/Security-Engineering-Building-Dependable-Distributed/dp/1119642787/ Viega & McGraw: Building Secure Software https://www.amazon.com/Building-Secure-Software-Security-Documents-ebook/dp/B003CW67YQ/
