Defensive programming: Difference between revisions

Revision as of 00:11, 11 May 2005

Revision as of 23:09, 18 June 2005

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* One of the most common problems is unchecked use of constant-size structures and functions for dynamic-size data (the [[buffer overflow]] problem). This is especially common for [[string]] data in [[C programming language|C]]. C library functions like <tt>gets</tt> and <tt>scanf</tt> should never be used since the maximum size of the input buffer is not passed as an argument. C library functions like <tt>scanf</tt> can be used safely, but require care with the selection of safe format strings.

* Never make code more complex than necessary. Complexity breeds bugs, including security problems.

* Either leave the code available to everyone on the Net (see [[Free software]] or [[Open Source Definition]]) or hire someone who will perform a software [[security audit]].

* If possible, reuse code instead of writing from scratch.

* Encrypt all important data transmitted over networks. Do not attempt to implement your own encryption scheme, but use a proven one instead.

* All data is important until proven otherwise.

* All code is insecure until proven otherwise.