[c22]

I would trust a bank who published their lock diagrams (or at least provided them to me on request) more than one that shrouded their security in secrecy. If I can look at the bank's diagrams I can verify that the lock has no obvious weaknesses, I can show the diagrams to my friends and through analysis we can determine if the lock seems secure enough for my needs. If the workings of the bank's vault are opaque to me the bank could easily be locking my safety deposit box with a twist-tie as a cost cutting measure.