Argument Against "Security Through Obscurity"

One objection to open source software is that it allows everyone to see what goes on in a program - and some of those people might be dishonest.  That being the case, some people suggest that software be kept a secret, that the source code not be published.  They think that in this way, it will put up an obstacle to help discourage malicious crackers from exploiting weaknesses in the software.  Keeping aspects of a program secret is sometimes referred to as "Security Through Obscurity."

The following quotation about lock smithing explains why security through obscurity isn't effective.

"A commercial, and in some respects a social, doubt has been started within the  last year or two, whether or not it is right to discuss so openly the security  or insecurity of locks.  Many well-meaning persons suppose that the discussion respecting the means for baffling the supposed safety of locks offers a  premium for dishonesty, by showing others how to be dishonest.  This is a fallacy.  Rogues are very keen in their profession, and already know much more than we can teach them respecting their several kinds of roguery.  Rogues knew a good deal about lockpicking long before locksmiths discussed it among themselves, as they have lately done.  If a lock -- let it have been made in whatever country, or by whatever maker -- is not so inviolable as it has hitherto been deemed to be, surely it is in the interest of *honest* persons to know this fact, because the *dishonest* are tolerably certain to be the first to apply the knowledge practically; and the spread of knowledge is necessary to give fair play to those who might suffer by ignorance.  It cannot be too earnestly urged, that an acquaintance with real facts will, in the end, be better for all parties."

-- Charles Tomlinson's Rudimentary Treatise on the Construction of Locks, published around 1850