Translation of "Unbreakable" in Japanese

The same unbreakable system that's protected us for decades,

破られることのない現代の暗号は

A much more complicated encryption scheme that they thought was unbreakable.

より高度に複雑で解読不能だと 考えられていた暗号方式です

That we thought was unbreakable and that was going to remain that way.

このような暗号はこの先もずっと 解読不能なものだと考えていました