As a theoretical or as a practical matter, is there ever actually any possible way to prove that you don't know something like a password? I imagine that the w

As a theoretical or as a practical matter, is there ever actually any possible way to prove that you don't know something like a password? I imagine that the way this would have to work in practice is that the prosecution would seek to prove that the accused did in fact know the password, and seek conviction on those grounds, rather than forcing the accused to refute unfounded accusations. But how it actually ends up working would depend on how the Irish legal system works. Wouldn't the presumption of innocence protect the accused from the impossibility of proving their ignorance? Wouldn't the prosecution need to produce clear evidence that the accused did in fact know a particular password (for instance, by demonstrating that they recently used the password to log into a particular system)? How badly could this actually be abused, in practice, in Ireland specifically?