Regarding cryptanalysis. yes it is known to happen that various proposed and sometimes implemented systems are found to be trivially breakable due to analysis not foreseen by their inventors. Examples are too numerous, but perhaps something like differential cryptanalysis might be something to look into.
Regarding cryptanalysis. yes it is known to happen that various proposed and sometimes implemented systems are found to be trivially breakable due to analysis not foreseen by their inventors. Examples are too numerous, but perhaps something like differential cryptanalysis might be something to look into.