Ne perderetur quomodo sensus communicetur voce anglica foolproof, dicerem aliquid et(iam) stultis idoneum esse. Hoc et vel etiam addo, nam mea sententia foolproof recte dici potest anglice alteris verbis significare, "even an idiot could not mess this up, so a fortiori you, who are not an idiot" (et stultus hoc destruere nequit, itaque quanto magis ipse tu, stultus qui non es.")
Si tamen libertas aliis utendi verbis mihi esset reddenti in latinam, uterer uno ex verbis Vergilio gratis: fidum (Lewis & Short, sensus IIus rebus exanimis pertinet): certus, fidelis, incolumis, fidedignus. Hoc modo defectuum absentia magis significatur.
Si altera ex parte conaris sensum "operandi simplicitatis" aut "quomodo falli potest?" communicare, forsan uti deberes his: facile (usu) vel planum, exempli gratia:
satin' haec sunt tibi plana et certa! (Plaut. Pers. 2, 2, 1)
In exemplo tuo, forsitan reddendum est duobus superioribus verbis implicatis:
Hoc systema securitatis facile fidumque est
Or, if you don't want to wade through the above quagmire: as my professor used to say when things got difficult in Latin: anglice paulisper:
If I wanted to preserve the same idea as foolproof, I would say something like et(iam) stultis idoneum. I add the et or etiam to stultis idoneum because I believe foolproof can be glossed as "even an idiot could not mess this up, a fortiori you, who are not an idiot."
That said, if I were translating this in a case that did not require this exact idiom, I would use one of Virgil's favorite words: fidum (Lewis & Short, meaning II for inanimate objects): sure, certain, safe, trustworthy. This emphasizes the "lack of failure" aspect of foolproof.
If, on the other hand, you are looking for the "simple to operate" or "what could go wrong?" sense, perhaps facile (usu) or planum, e.g.:
satin' haec sunt tibi plana et certa! (Plaut. Pers. 2, 2, 1)
In your example, perhaps a good translation would combine two of these suggestions:
Hoc systema securitatis facile fidumque est